material from the ,google ,print project47 ---------------------------------------- ----------------------------- ,transcriber's notes3 99 ,text in italics in the original document is presented here between underscores1 as in text4 99 ,bold-face text in the original document is presented here between equal signs1 as in text4 99 ,old-,english font is presented here by enclosing the text between 1 as in text4 99 ,superscript and subscript are presented as text and text1 respectively4 99 ,the oe-ligature is presented as oe as in diarrhoea4 99 ,small-caps text in the original document is presented as all-caps here4 99 ,the equilibrium arrow in chemical reactions is presented here as 4 99 ,footnotes 7indicated by ,a1 ,b1 etc47 have been moved to directly below the paragraph or table they refer to1 references 7indicated by #a1 #b1 etc47 are collected at the end of each chapter4 99 ,greek in the original document has been transcribed as for example alpha for individual letters and as ,greek3 chloros for complete words4 99 ,positive and negative ions are presented as for example ,h4 and ,,oh'1 as in the original document4 ,see additional ,transcriber's ,notes at the end of this e-text4 ---------------------------------------- ----------------------------- ,,works ,,of ,,joseph ,,race ,,published ,,by ,,john ,,wiley ,,sons1 ,inc4 ,examination of ,milk for ,public ,health ,purposes4 ,a practical handbook for those engaged in the chemical and bacteriological examination of milk for public health purposes4 vi #bbd pages1 #e-a_/d x #h1 #d diagrams4 ,cloth1 #a4ge net4 ,chlorination of ,water4 ,in this book the various aspects and methods of chlorination are discussed with a view to stimulating research work in this field of science4 viii #aeh pages1 #e-a_/d x #h1 #ab figures and #af diagrams4 ,cloth1 #a4ej net4 ,chlorination of ,water ,,by ,,joseph ,,race1 ,f4,i4,c4 ,city ,bacteriologist and ,chemist1 ,ottawa2 ,capt4 ,canadian ,army ,hydrological ,corps2 ,associate ,member of ,committee on ,water ,supplies1 ,american ,public ,health ,association2 ,member of ,committee on ,water ,standards and ,standard ,methods of ,analysis1 ,american ,water ,works ,association2 ,chairman of ,committee on ,standard ,methods of ,analysis1 ,canadian ,public ,health ,association ,,first ,,edition ,,new ,,york ,,john ,,wiley ,,sons1 ,,inc4 ,,london3 ,,chapman ,,hall1 ,,limited #aiah ,copyright1 #aiah ,,by ,,joseph ,,race1 ,f4,i4,c4 ,,press ,,of ,,braunworth ,,co4 ,,book ,,manufacturers ,,brooklyn1 ,n4 ,y4 ,,dedicated ,,to ,sir ,alexander ,houston1 ,k4,b4,e41 ,d4,sc41 ,m4,b41 ,c4,m4 ,,preface ,no apology is necessary for the publication of a book on the chlorination of water4 ,this method of treatment1 practically unknown fifteen years ago1 has advanced in popularity during the last decade in a most remarkable manner1 and in #aiah over forty millions of people are being supplied with chlorinated water4 ,it may justifiably be said that no other sanitary measure has accomplished so much at so small a cost2 and that civilization owes a deep debt of gratitude to the pioneers in municipal water chlorination3 ,dr4 ,a4 ,c4 ,houston in ,england1 and ,mr4 ,g4 ,a4 ,johnson and ,dr4 ,leal in ,america4 ,in this volume ,i have endeavoured to collect and correlate the information hitherto scattered in various journals and treatises and to present it in a comprehensible manner4 ,the various aspects and methods of chlorination are discussed and suggestions have been made which1 ,i hope1 will stimulate research work in this fertile field of science4 ,i wish to acknowledge my indebtedness to the engineering staff of the ,ottawa ,water ,works ,department and to ,lieut4 ,w4 ,m4 ,bryce for the preparation of diagrams4 ,,joseph ,,race4 ,,ottawa1 ,,ont41 ,april1 #aiah4 ,,contents ,,chapter ,,page ,i4 ,,historical #a ,sodium ,chloride4 ,chlorine4 ,bleach4 ,eau de ,javelle4 ,antiseptics4 ,hermite fluid4 ,webster's process4 ,electrozone4 ,chlorination of sewage in ,germany1 ,u4 ,s4 ,a41 and ,england4 ,chlorination of water4 ,lincoln installation4 ,oxychloride4 ,german experiments4 ,european practice4 ,inception of chlorination in ,america4 ,,ii4 ,,modus ,,operandi #ad ,composition of bleach4 ,bleaching action4 ,nascent oxygen hypothesis4 ,hydrolysis of bleach4 ,effect of acids and salts on hydrolysis and germicidal action4 ,effect of ammonia4 ,direct toxic action4 ,hypochlorous acid4 ,sodium hypochlorite4 ,chlorine water4 ,nature of action4 ,,iii4 ,,dosage #cj ,organic matter4 ,initial count4 ,viability of organisms4 ,mineral matter4 ,colour4 ,temperature4 ,admixture4 ,contact period4 ,turbidity4 ,light4 ,determination of dosage4 ,,iv4 ,,bacteria ,,surviving ,,chlorination #ej ,disinfectants4 ,antiseptics4 ,viability of bacteria4 ,new ,york results4 ,reversed ratio of counts4 ,coliform organisms4 ,aftergrowths in water and sand4 ,v4 ,,complaints #fb ,auto-suggestion4 ,tastes and odours4 ,sludge problem4 ,colic4 ,effect on fish and birds4 ,effect on plants and flowers4 ,corrosion of iron and lead pipes4 ,,vi4 ,,bleach ,,treatment #gb ,storage of bleach4 ,mixing tanks4 ,storage tanks4 ,dosing apparatus4 ,control4 ,analysis of liquor4 ,detection and estimation of free chlorine4 ,chlorometer4 ,cost of construction and operation4 ,antichlors4 ,de,chlor filters4 ,,vii4 ,,liquid ,,chlorine #hi ,historical4 ,leavitt-,jackson machine4 ,electro ,bleaching ,gas ,co4's types4 ,wallace and ,tiernan's manual control types4 ,effect of temperature on gas pressure4 ,impurities in gas4 ,advantages4 ,comparison of liquid chlorine and bleach4 ,cost of treatment4 ,popularity4 ,chlorine water4 ,,viii4 ,,electrolytic ,,hypochlorites ,,and ,,chlorine #aje ,hermite fluid4 ,eau de ,javelle4 ,chloros4 ,non-diaphragm cells3 ,dayton1 ,hermite1 ,mather and ,platt1 ,haas and ,oettel4 ,diaphragm cells3 ,hargreaves-,bird1 ,nelson1 ,allen-,moore4 ,montreal installation4 ,costs4 ,,ix4 ,,chloramine #aae ,preparation4 ,absorption by water4 ,experimental results4 ,works results4 ,ratio of chlorine to ammonia4 ,economics4 ,advantages4 ,operation4 ,other chloramines4 ,halazone4 ,x4 ,,results ,,obtained #acb ,object of chlorination4 ,effect on filter rates and algae4 ,hygienic results4 ,typhoid rates4 ,typhoid reduction at ,philadelphia1 ,chicago1 and ,ottawa4 ,abortive epidemics4 ,use and abuse of chlorination4 ,,appendix #adg ,estimation of free chlorine in water4 ,,name ,,index #aea ,,subject ,,index #aee ,,chlorination ,,of ,,water ,,chapter ,i ,,historical ,chlorine1 although one of the most widely distributed elements known to chemists1 is never found in the free condition in nature2 it exists in enormous quantities in combination with sodium1 potassium1 calcium1 magnesium1 etc4 ,as sodium chloride1 common salt1 it occurs in practically inexhaustible quantities in sea water together with smaller quantities of other chlorides4 ,in mineral form1 enormous deposits of sodium chloride are found in ,galicia1 ,transylvania1 ,spain1 in ,england 7particularly in ,cheshire71 and in sections of ,north ,america4 ,the most important deposits of potassium chloride are those at ,stassfurt1 ,germany1 where it occurs either in the crystalline condition as sylvine or combined with magnesium chloride as carnallite4 ,chlorine was discovered by the ,swedish chemist ,scheele in #aggd1 but he1 like ,lavoisier and his pupil ,berthollet1 who declared it an oxygenated muriatic acid1 was unaware of the elemental nature of the new substance4 ,sir ,humphrey ,davy investigated this body in #ahaj and definitely proved it to be an element2 ,davy designated the element chlorine from the ,greek ,greek3 chloros green4 ,the first attempt to utilise chlorine1 or its compounds1 for bleaching purposes1 appears to have been due to ,james ,watt1 who noticed the decolourising properties of chlorine during a visit to ,berthollet4 ,this attempt ended in failure because of the destructive effect on the fibres1 but1 in later trials1 this was prevented by first absorbing the gas in a solution of fixed alkali4 ,these experiments proved the possibility of bleaching by means of chlorine compounds but the high cost of soda made the process unprofitable1 and it was not until ,henry succeeded in preparing a combination with lime that could be reduced to a dry powder that this mode of chemical bleaching became a commercial success4 ,the manufacture of chloride of lime 7hypochlorite of lime1 bleaching powder1 bleach7 was taken up by ,charles ,tennant in #agii at ,st4 ,rollox near ,glasgow1 and in #ahjj about #ej tons were sold at a price of #fhj 7,l#aci7 per ton4 ,chlorine is produced as a by-product in the manufacture of soda by the ,leblanc process1 but until #ahfe1 when the ,british ,alkali ,act stopped the discharge of hydrochloric acid vapours into the atmosphere1 the development of the bleaching powder industry was not rapid4 ,the hydrochloric acid that was formerly discharged into the air as a waste product afterwards became a valuable asset that enabled the ,leblanc process to successfully compete with the newer ammonia-soda process4 ,in #ahij another competitor to the ,leblanc process was introduced when caustic and chlorine were produced in ,germany by electrolytic methods4 ,after the successful development of this method in ,germany1 it was taken up in the ,united ,states of ,america and in #aiab more than #cj1jjj electrical horse-power were daily used in this industry4 ,in #aiad the almost complete cessation of exports of bleach from ,europe raised the price1 which attained phenomenal heights in #aiaf 7cf4 page #abe71 and stimulated the production of bleach both in the ,u4 ,s4 ,a4 and ,canada4 ,,table ,i4--,,bleach ,,statistics4 ,,north ,,america ---------------------------------------- ---------------------- ,year4 ,bleach ,manufactured1 ,selling ,price ,short ,tons4 ,per #ajj ,lbs4 ---------------------------------------- ---------------------- #aijd #ai1jjj #aiji #eh1jjj #aiad #aee1jjj #a4fc #aiae #ahj1jjj;,a #b4fc #aiaf #bcj1jjj;,a #f4ef #aiag #bfj1jjj;,a #b4dd ---------------------------------------- ---------------------- ,a ,estimated4 ,as a disinfectant1 chlorine was first used about the year #ahjj by de ,morveau1 in ,france1 and by ,cruikshank1 in ,england1 who prepared the gas by heating a mixture of hydrochloric acid and potassium bichromate or pyrolusite2 this is essentially the same as the original mixture used by ,scheele4 ,during the early part of the last century the efficacy of chlorine of lime as a disinfectant1 and particularly as a deodourant1 was well recognised and as early as #ahed an ,english ,royal ,commission used this substance for deodourising the sewage of ,london4 ,a committee of the ,american ,public ,health ,association reported in #ahhe that chloride of lime was the best disinfectant available when cost and efficiency were considered4 ,eau de ,javelle1 first made by ,percy at the ,javelle works near ,paris in #agib1 is another chlorine compound that has enjoyed a considerable reputation as a disinfectant and deodouriser for over a century2 it is essentially a mixture of sodium chloride and sodium hypochlorite4 ,the discovery of electrolytic hypochlorites dates back to #ahei1 when ,watt found that chlorides of the fixed alkalies and alkaline earths yielded hypochlorites on being submitted to the action of an electrical current4 ,until the middle of the last century disinfection was regarded as a process that arrested or prevented putrefactive changes but the nature of these changes was imperfectly comprehended and micro-organisms were not associated with them4 ,in #ahci ,theodor ,schwann1#a who might be regarded as the founder of the school of antiseptics1 reported that ,fermentation is arrested by any influence capable of killing fungi1 especially by heat1 potassium arseniate1 etc44442 but his results were not accepted by the adherents of the theory of spontaneous generation and it was not until the publication of the work of ,schroder and ,dusch#b that ,schwann's views were even partially accepted4 ,the final refutation to the spontaneous generation theory was given by the monumental researches of ,pasteur who1 in #ahfb1 proved the possibility of preparing sterile culture media and demonstrated the manner in which they could be protected from contamination4 ,bacteria and other micro-organisms were shown to be responsible for the phenomena that had been attributed previously to the oxygen of the air1 and from this period the development of bacteriology as a science proceeded rapidly4 ,the next important step1 from the public health standpoint1 was the discovery by ,koch1 in #ahgf1 that a specific bacterium 7,b4 anthracis7 was the cause of a specific disease in cattle 7anthrax or splenic fever74 ,in #ahhb ,koch made a further advance by developing a solid culture medium which permitted disinfectants and antiseptics to be studied quantitatively with a greater degree of accuracy than had been possible previously4 ,since #ahde1 when ,semmelweiss succeeded in stamping out puerperal fever in ,vienna1 where it had been so long established as to be endemic1 chlorine has been very generally employed in sanitary work and the conditions necessary for obtaining successful results have been partially elucidated4 ,baxter was the first to state that the disinfecting action depended more upon the nature of the pabulum than upon the specific organism present and this was confirmed later by ,kuhn1 ,bucholtz1 and ,haberkorn4 ,the latter found that urine consumed large quantities of chlorine before any disinfection occurred4 ,one of the earliest preparations used in sanitary work was an electrolysed sea water1 usually known as ,hermite ,fluid4 ,this was introduced by ,m4 ,hermite in #ahhi and was employed for domestic purposes and for flushing sewers and latrines4 ,it was used at ,brest for the dissolution of faecal matter and a prolonged trial was given to it at ,worthing in #ahid4 ,the report of ,dupre and ,klein1 who conducted the bacteriological examinations1 was against the process1 but ,ruffer and ,roscoe reported more favourably and further trials were carried out at ,havre1 l',orient1 and ,nice4 ,the ,lancet 7,may #bf1 #ahid7 reported at length upon the ,worthing experiments3 it was found that during the electrolysis of the sea water1 the magnesium chloride was also partially converted into hypochlorite1 which then dissociated into magnesium hydrate and hypochlorous acid2 the former deposited in the electrolyser and left the solution acid and unstable2 urine was found to act upon it at once with a consequent loss in strength of over #ej per cent4 ,another electrolytic method was that of ,webster1#c who installed an experimental plant at ,crossness1 near ,london1 in #ahhi4 ,a low-tension direct current was passed between iron electrodes placed in the sewage and although the process was largely one of chemical precipitation1 ,webster noted the disinfecting value of the hypochlorite formed from the chlorides normally present in the sewage4 ,he also directed the attention of sanitarians to the possibility of using sea water as a cheap source of chlorides and a plant based on this principle was erected in ,bradford in #ahij and reported upon by ,mc,lintock4#d ,strong salt solutions were substituted for sea water by ,woolf and the product was commercially known as ,electrozone4 ,a plant of this description was installed at ,brewster1 ,n4 ,y41 in #ahice for chlorinating the sewage from a small group of houses4 ,the sewage was discharged into a small creek which polluted ,croton ,lake4 ,successful results led to a similar treatment near ,tonetta ,creek4#f ,this was apparently the first occasion on which the specific object was the destruction of bacteria4 ,electrozone was used at ,maidenhead1 on the ,thames1 in #ahig and the installation was reported upon by ,robinson1 ,kanthack1 and ,rideal in #ahih4 ,kanthack found that a dosage #c-c4f p4p4m4 reduced the organisms in a sewage effluent to #aj-ej per c4cm4 whilst ,rideal found that about #ah p4p4m4 of chlorine produced a condition of sterility in #a c4cm4 ,chloride of lime had previously been used in the ,london sewage as a deodourant by ,dibden in #ahhd but the treatment was not successful and was abandoned in favour of other oxidisers4 ,during the last decade of the twentieth century the use of bleach for the disinfection of both sewage and water received the attention of many well-known ,german sanitarians and many important results were obtained4 ,in the earlier experiments made at ,hamburg1 ,proskauer and ,elsner#g obtained satisfactory results with #c-d p4p4m4 of chlorine on a clarified sewage with #aj minutes contact4 ,dunbar and ,zirn 7ibid47 used crude sewage and found that #ag p4p4m4 of available chlorine were required to remove ,b4 typhosus and cholera vibria with a contact period of two hours4 ,a striking feature of all the ,german work on chlorination is the very high degree of purification aimed at3 quantities as large as one litre were tested for specific organisms and in many of the experiments with sewage ,b4 coli was found to be absent from a considerable percentage of the samples4 ,the importance of previously removing suspended matter1 which could not be penetrated by the germicide1 was emphasised by ,schwartz#h although it had been previously noted by ,schumacher4 ,at the ,royal ,testing ,station in ,berlin1 numerous experiments on sewage chlorination were made by ,kranejuhl and ,kurpjuivut4#i ,the results were judged by the ,b4 coli content1 which was taken as an index of pathogenicity because this typical intestinal bacillus was found to be more frequent and less viable than the majority of the pathogenic organisms4 ,other important work on this subject was carried out1 in connection with the pollution of the ,hooghly ,river1 by a ,bengal ,government ,commission in #aijd2 and by the ,state ,board of ,health of ,ohio in co-operation with the ,bureau of ,plant ,industry of the ,united ,states ,department of ,agriculture in #aijg4 ,the chlorination experiments of the latter were reported by ,kellerman1 ,pratt1 and ,kimberly4#aj ,the most valuable contribution to the disinfection of sewage was that of ,phelps1#aa who critically examined the work of previous experimenters and directed attention to the unnecessary stringent standards adopted in ,european practice4 ,his work at ,boston in #aijf1 at ,red ,bank1 ,n4 ,j41 and at ,baltimore in #aijg1 demonstrated in an indubitable manner the economic possibilities of sewage chlorination4 ,the dosages necessary for crude sewage and filter effluents were indicated and also the necessary contact periods4 ,this work marks the commencement of a new era in sanitary science4 ,the first occasion on which chlorine compounds were first used for the disinfection of water cannot be definitely ascertained4 ,it has been stated to the author that bleach was used for treating wells as early as #ahej but this treatment was apparently made without definite knowledge of the destruction of micro-organisms4 ,in #ahig1 ,sims ,woodhead employed bleach solutions for the sterilisation of the distribution mains at ,maidstone1 ,kent1 subsequent to an epidemic of typhoid fever4 ,the credit for the first systematic use of chlorine in water disinfection is due to ,a4 ,c4 ,houston with whom ,mc,gowan was associated in the work carried out at ,lincoln in #aijd-aije4ab ,the reservoirs1 filters1 and distribution system1 owing to flood conditions1 became infected with typhoid bacilli which caused a severe epidemic amongst the consumers4 ,the storage and purifications works were thoroughly treated with a solution of chloros 7sodium hypochlorite containing approximately #aj per cent of available chlorine7 which was regulated to give an approximate dosage of #a part per million4 ,the bacteriological results were entirely satisfactory but many complaints were received that the treatment had imparted a mawkish taste to the water4 ,this was attributed to the action of the alkaline chloros on the organic impurities in the water4 ,it was also stated that the water injured plants1 fish1 and birds and extracted abnormal amounts of tannin from tea but no substantiating evidence was produced in support of these complaints4 ,houston made a continuous physiological test of the effect of the chlorinated water on small fish by suspending a cage of gold fish in the filter effluent chamber and also proved that the treatment had no appreciable effect on the plumbo-solvency of the supply4 ,nesfield1 of the ,indian ,army ,medical ,service1#ac reported in #aijc the results of numerous experiments on the destruction of pathogenic organisms by chlorine compounds and suggested their use in military work to prevent a recurrence of the appalling loss of life from water-borne diseases 7especially enteric fever7 such as took place during the ,boer ,war4 ,nesfield proposed to use about #ajj p4p4m4 of available chlorine and to remove the excess after a contact period of #aj minutes4 ,this work is especially interesting from the historical standpoint because it contains the first suggestion of the possibilities of compressed chlorine gas in steel cylinders4 ,a few years later1 electrolytic hypochlorite 7oxychloride7 was used at ,guildford by ,rideal and various chlorine compounds were tried on the water of the ,seine and ,vanne1 in ,france1 and at ,middlekerke and ,ostend1 in ,belgium4 ,experimental work on water chlorination was also reported by ,thresh and by ,moor and ,hewlett4#ad ,during the nineties many experiments on water chlorination were made by ,traube1 ,sickenberger1 ,kauffman1 ,berge1 ,bassenge1 and others4 ,traube#ae was able to completely sterilise water rich in bacteria in #b hours by the addition of bleach equal to #a4jf p4p4m4 of available chlorine4 ,at the end of the contact period about #ij per cent of the added chlorine was unabsorbed and was destroyed by the addition of sodium bisulphite4 ,bassenge#af followed up the work of ,traube and that of ,sickenberger and ,kauffman1 who had shown that it was possible to destroy cholera vibrio in ,nile water by means of sodium hypochlorite4 ,bassenge used higher concentrations than ,traube and found it possible to destroy ,b4 typhosus and ,b4 coli in ten minutes with #fj-ij p4p4m4 of available chlorine4 ,the excess was destroyed by adding calcium bisulphite4 ,lode#ag experimented with waters seeded with ,b4 coli1 ,b4 typhosus1 and ,b4 tetani and found1 contrary to ,traube1 that #a-b p4p4m4 of chlorine did not sterilise in two hours4 ,b4 coli was usually destroyed by #d p4p4m4 of chlorine in ten minutes and even better results were obtained with ,b4 typhosus and cholera vibrio3 the former was destroyed in one hour by #a p4p4m4 and in ten minutes by #b p4p4m42 the latter organism required #a-b p4p4m4 with a twenty-minute contact period4 ,lode noted that organic matter lowered the bactericidal activity of chlorine and recommended the use of #cj p4p4m4 of chlorine to ensure rapid and complete sterilisation4 ,berge#ah used chlorine peroxide1 generated by the action of hydrochloric acid on potassium chlorate1 for the sterilisation of water and this process was afterwards used at ,ostend at a plant having a capacity of about #a1cjj1jjj gallons per day4 ,the dosage was equal to #j4ec p4p4m4 of available chlorine and coke filters were used to destroy the excess although they were not found to be indispensable as the free chlorine disappeared spontaneously4 ,this process appears to have been tried on the ,brussels supply and also for the treatment of a hospital supply at ,petrograd4 ,the object of ,german sanitarians seems to have been to obtain practically instantaneous sterilisation of water for the use of travellers and troops in the field4 ,until the commencement of the ,european ,war they did not have a high opinion of chlorination and generally regarded it as inefficient4 ,schumberg#ai expressed the opinion that no chemical method of disinfection could be absolutely relied upon1 under all circumstances1 to prove fatal to bacteria4 ,plucker#bj stated that several investigators1 particularly ,schuder1 had shown that chlorine1 even in the proportion of #dj p4p4m4 did not invariably destroy cholera vibrio and ,b4 typhosus2 and that with smaller doses the destruction was still less complete4 ,he also stated that the bacteriological experiments of ,american workers were open to criticism and that they employed antiquated methods4 ,by #aiaf the ,german sanitarians appeared to have realised that their bacteriological standards were too stringent 7,langer#ba7 and that the process had proved its value in an indisputable manner4 ,european practice1 in the comparatively few instances in which it has been used1 has been to employ large doses of chlorine and to remove the excess by chemicals or by filtration through special media4 ,in #aiaf1 however1 ,london commenced to chlorinate a portion of its supply and the following year practically the whole supply was chlorinated4 ,a dosage of approximately #j4e p4p4m4 is used and the bleach solution is added to the pre-filtered water4 ,worcester is also proposing to chlorinate the supply to maintain the purity of the water without extending the slow sand filtration plant4 ,in ,north ,america1 hypochlorite of soda and chlorine were used on the ,jewell ,filter at the ,louisville ,experimental ,station in about #ahif by ,george ,w4 ,fuller and a year later they were used at ,adrian by ,jewell4 ,the first commercial successful attempt was made by ,g4 ,a4 ,johnson4 ,in #aijh the ,union ,stock ,yards ,company of ,chicago were proceeded against by the ,city of ,chicago regarding the condition of the effluent of the ,bubbly ,creek filter plant4 ,copper sulphate had been previously used in conjunction with the filters but stock shippers complained that the water had a deleterious effect upon the animals consuming it4 ,johnson eliminated the copper treatment and substituted bleach which was added seven and a half hours previous to filtration1 with a dosage of #a4e p4p4m4 ,the results were very satisfactory4 ,about the same time1 ,johnson and ,leal commenced the treatment of the ,boonton supply of ,jersey ,city1 ,n4 ,j41 consumed about #dj million gallons per day4 ,the water was first treated with #cf pounds of bleach per million gallons 7#a4d p4p4m4 of available chlorine7 but this quantity was gradually reduced until only #e pounds per million gallons 7#j4b p4p4m4 of chlorine7 were being used in ,april1 #aiji4 ,the ability of the process to adequately purify water became the cause of a lawsuit and the decision of the ,court was3 ,from the proofs taken before me1 of the constant observation of the effect of this device1 ,i am of the opinion and find that it is an effective process which destroys in the water the germs1 the presence of which is deemed to indicate danger1 including the pathogenic germs1 so that the water after this treatment attains a purity much beyond that attained in water supplies of other municipalities4 ,the reduction and practical elimination of such germs from the water was shown to be substantially continuous4 ,upon the proofs before me1 ,i find that the solution described leaves no deleterious substances in the water4 ,it does produce a slight increase in the hardness but the increase is so slight as in my judgment to be negligible4 ,i do therefore find and report that this device is capable of rendering the water delivered in ,jersey ,city pure and wholesome1 for the purposes for which it is intended and is effective in removing from the water those dangerous germs which were deemed by the decree to possibly exist therein at certain times4#bb ,during the next few years the use of hypochlorite in water purification1 both alone and in conjunction with filtration1 became very popular and in #aiaa over #hjj million gallons per day were treated in this manner4 ,amongst the users were some of the largest cities in ,north ,america1 including ,brooklyn1 ,albany1 and ,new ,york ,city1 ,n4 ,y41 ,cincinnati and ,columbus1 ,ohio1 ,harrisburg1 ,philadelphia1 ,pittsburg1 and ,erie1 ,pa41 ,hartford1 ,conn41 ,nashville1 ,tenn41 ,st4 ,louis and ,kansas ,city1 ,mo41 ,montreal1 ,p4 ,q41 ,toronto and ,ottawa1 ,ont41 ,baltimore1 ,md41 and ,minneapolis1 ,minn4 ,at present 7#aiah7 over #c1jjj million gallons per day are being chlorinated in ,north ,america and more than #a1jjj cities and towns are employing this process4 ,,bibliography #a ,schwann4 ,microskopische ,untersuchungen ueber die ,uebereinstimmung in der ,textur und dem ,wachstum der ,tiere und ,pflanzen4 ,berlin4 #ahci #b ,schroder and ,dusch4 ,ann4 der ,chem4 u4 ,pharm41 #ahed1 #hi1 #bcb4 #c ,webster4 ,the ,engineer4 #ahhi1 #fg1 #bfa4 #d ,mc,lintock4 ,brit4 ,med4 ,jour41 #ahij1 #aa1 #dih4 #e ,eng4 ,news4 #ahic1 #cj1 #da4 #f ,eng4 ,record4 #ahid1 #bi1 #aaj4 #g ,proskauer and ,elsner4 ,vierteljahresschr4 ger4 ,med4 u4 oeff4 ,sanitaetswesen4 #ahih1 #af1 ,supp4 ,heft4 #h ,schwartz4 ,gas4 ,eng41 #aijf1 #bi1 #ggc4 #i ,kranejuhl and ,kurjuivut4 ,mitteilungen aus der ,koeniglichen ,pruefungsanstalt fuer ,wasserversorgung und ,abwaesserbeseitigung zu ,berlin1 #aijg1 #i1 #adi4 #aj ,kellerman1 ,pratt1 and ,kimberly4 ,bull4 #aae1 ,bur4 ,plant ,ind41 ,u4 ,s4 ,dept4 of ,agr41 #aijg4 #aa ,phelps4 ,water ,supply ,paper #bbi1 ,dept4 of ,int41 ,u4 ,s4 ,geo4 ,survey4 #ab ,houston and ,mc,gowan4 #eth ,rpt4 ,royal ,commission on ,sewage ,disposal4 #ac ,nesfield4 ,public ,health4 #aijc1 #ae1 #fja4 #ad ,moor and ,hewlett4 ,rpt4 of ,m4 ,o4 to ,l4 ,g4 ,b41 #aiji-aj4 #ae ,traube4 ,zeit4 f4 ,hyg41 #ahid1 #af1 #adi4 #af ,bassenge4 ,zeit4 f4 ,hyg41 #ahie1 #bj1 #bbg4 #ag ,lode4 ,archiv4 f4 ,hyg41 #ahie1 #bd1 #bcf4 #ah ,berge4 ,rev4 d',hyg41 #aijj1 #bb1 #ije4 #ai ,schumburg4 ,zeit4 f4 ,hyg41 #aijc1 #de1 #abe4 #bj ,plucker4 ,j4 ,gasbeleucht41 #aiaa1 #ed1 #che4 #ba ,langer4 ,zeit4 f4 ,hyg41 #aiaf1 #ha1 #bif4 #bb ,johnson4 ,jour4 ,amer4 ,pub4 ,health ,assoc41 #aiaa1 #a1 #eff4 ,,chapter ,,ii ,,modus ,,operandi ,before considering the modus operandi of chlorine and hypochlorites1 it will be advisable to take up the composition of the latter substances and particularly that of bleach4 ,bleach is manufactured by passing chlorine gas over slaked lime and the ensuing reactions are often represented by the equation ,ca7,,oh7#b ,cl#b ,ca,o,cl#b ,h#b,o4 ,this represents the substance formed as a pure oxychloride of calcium which contains approximately #ej per cent of chlorine1 but the article commercially produced never contains this amount of chlorine1 the usual percentage being from #ce-cg4 ,the general composition of commercial bleach is fairly uniform4 ,this is shown in the following analyses of which two are of ,german bleach examined by ,lunge and one of ,canadian manufacture analysed by the author4 ---------------------------------------- --------------- ,lunge4 ,race4 ---------------------------------------- -------------- ,available chlorine #cg4jj #ch4cj #cg4ej ,chlorine as chlorides #j4ce #j4ei #j4eb ,chlorine as chlorates #j4be #j4jh #j4ah ,lime #dd4di #dc4cd #dd4ab ,magnesia #j4dj #j4ca #a4bh ,iron oxide #j4je #j4jd #j4aa ,alumina #j4dc #j4da #j4df ,carbon dioxide #j4ah #j4ca #j4bb ,silica #j4dj #j4cj #j4eb ,water and undetermined #af4de #af4cb #ae4ji ---------------------------------------- -------------- ,from these analyses the constitutional of commercial bleach might be represented by the formula #d;,ca,o,cl#b4b;,ca7,,oh7#b4e;,h#b,o which assumes it to contain3 #fh4j per cent of calcium hypochlorite1 #bj4j per cent of calcium hydroxide1 and #ab4j per cent of water4 ,in this formula calcium hypochlorite has been written ,ca,o,cl#b1 but this substance actually contains one atom of oxygen less than the true hypochlorite1 which has the constitutional formula ,cl,o-,ca-,o,cl4 ,this difference led some of the earlier chemists to regard ,ca,o,cl#b as a mixture of equal molecules of calcium chloride and calcium hypochlorite 7,ca,cl#b ,ca7,o,cl7#b #b;,ca,o,cl#b71 but it has been definitely established that no calcium chloride exists in the free state in dry commercial bleach4 ,since the very earliest days when the process of bleaching was investigated it was considered to be a process of oxidation and it is not surprising that ,lavoisier and his pupils1 who had noted the strong decolourising action of the gas discovered previously by ,scheele1 should regard it as a compound that contained oxygen4 ,they were confirmed in this view by the fact that an aqueous solution of the gas slowly evolved oxygen when placed in bright sunlight1 and lost its bleaching properties4 ,watt disproved this and showed that the evolution of oxygen was due to the action of the chlorine on water4 ,cl#b ,h#b,o #b;,h,cl ,o4 ,the bleaching action was not due to the chlorine per se but to the nascent oxygen produced in the presence of moisture4 ,later1 when bleach and other chlorine compounds came into use as deodourisers1 their action was attributed to the oxygen produced and when their germicidal properties became known it was natural to assume that the destruction of bacteria was due to the same cause4 ,some of the earlier experimental work supported this view4 ,fischer and ,proskauer#a found that humidity played an important part in chlorine disinfection1 probably because it favoured oxidation4 ,in air saturated with moisture micro-organisms were killed by #j4c per cent of chlorine in three hours but when the air was dry practically no action occurred4 ,they concluded that chlorine was not directly toxic4 ,warouzoff1 ,winogradoff1 and ,kolessnikoff#b were unable to confirm the results of ,fischer and ,proskauer and found that a mixture of chlorine gas and air killed tetanus spores in one minute4 ,the nascent oxygen hypothesis was clearly and succinctly expressed by ,prof4 ,leal during the hearing of the ,boonton1 ,n4 ,j41 case and the following abstracts have been taken from his evidence3 444 ,that on the addition of bleach to water the loosely formed combination forming the bleach splits up into chloride of calcium and hypochlorite of calcium4 ,the chloride of calcium being inert1 the hypochlorite acted upon by the carbonic acid in the water either free or half bound1 splits up into carbonate of calcium and hypochlorous acid4 ,the hypochlorous acid in the presence of oxidisable matter gives off its oxygen2 hydrochloric acid being left4 ,the hydrochloric acid then drives off the weaker carbonic acid and unites with the calcium forming chloride of calcium4 ,that the process was wholly an oxidising one1 the work being done entirely by the oxygen set free from the hypochlorous acids in the presence of oxidizable matter4444 ,we have used during our investigations1 the term 'potential oxygen' as expressing its factor of power4 ,when set free1 it is really nascent or atomic oxygen and is1 in its most active state1 entirely different from the oxygen normally in water4444 ,the reactions suggested are expressed in the following equations3 7i74 #b;,ca,o,cl#b ,ca,cl#b ,ca7,o,cl7#b 7ii74 ,ca7,o,cl7#b ,,co#b ,h#b,o ,ca,c,o#c #b;,h,cl,o 7iii74 #b;,h,cl,o #b;,h,cl ,o#b 7iv74 ,ca,c,o#c #b;,h,cl ,ca,cl#b ,,co#b ,h#b,o4 ,phelps1 during the hearing of this case1 suggested that hypochlorites were directly toxic to micro-organisms but this view was not supported by any definite evidence and the nascent oxygen hypothesis met with almost universal acceptance4 ,investigations made by the author in #aiae1 #aiaf and #aiag have produced data which cannot be adequately explained by the nascent oxygen hypothesis4#c ,the disinfecting action of bleach can be most conveniently considered by regarding it as a heterogeneous mixture of the reactants and resultants of the reaction ,ca,o ,h#b,o ,cl#b ,ca,o,cl#b ,h#b,o which is in equilibrium for the temperature and pressure obtaining during the process of manufacture4 ,under suitable physical conditions the chlorine content can be increased to #dj-db per cent but such a product is not so stable as those represented by the analyses on page #ad and which contain approximately #bj per cent of excess hydrate of lime4 ,the stability of bleach depends upon this excess of base 7,griffen and ,hedallen#d7 and although magnesia can be partially substituted for this excess of lime1 a minimum of #e per cent of free hydrate of lime is required to ensure stability4 ,on dissolving bleach in water the first action is the decomposition of calcium oxychloride into an equal number of molecules of calcium hypochlorite and calcium chloride4 #b;,ca,o,cl#b ,ca7,o,cl7#b ,ca,cl#b4 ,in dilute solution these salts are dissociated and hydrolysis tends to occur in accordance with the equations #b;,ca7,o,cl7#b #d;,h#b,o #b;,ca7,,oh7#b ,h,o,cl ,h,cl and ,ca,cl#b #b;,h#b,o ,ca7,,oh7#b #b;,h,cl4 ,calcium hydrate and hydrochloric acid are both practically completely dissociated1 i4e4 there is a large and equal quantity of ,h4 and ,,oh'1 and the product is much greater than ,kw 7ionic product of water71 and hence there is a combination of these ions1 leaving the solution neutral and no undissociated acid or base exists4 ,this statement is only approximately correct as hydrochloric acid is slightly more dissociated than calcium hydroxide 7ratio #i3h7 and the solution is consequently slightly acid1 i4e4 the ,h4 concentration is greater than #a x #aj-g4 ,hypochlorous acid is only very slightly dissociated1 especially in the presence of the ,o,cl' ion due to the dissociation of the ,ca7,o,cl7#b1 as compared with ,ca7,,oh7#b and hydrolysis of the ,ca7,o,cl7#b proceeds with increased dilution4 ,the action is best represented by the equation #b;,ca7,o,cl7#b #b;,h#b,o ,ca,cl#b ,ca7,,oh7#b #b;,h,o,cl ,the hydrolytic constant of hypochlorous acid has apparently not been determined but as the acid is weaker than carbonic acid1 which has a hydrolytic constant of #a x #aj-d1 the value is probably between #a x #aj-c and #a x #aj-d4 ,from the formula x#b_/7a - x7v kwv in which #a mole of pure ,ca7,o,cl7#b is dissolved in v litres1 x is the fraction hydrolysed1 and kwv is the hydrolytic constant1 complete hydrolysis occurs 7x #a7 when v is not greater than #a x #ajd litres4 ,this is equivalent to a concentration of not less than #g4a p4p4m4 of available chlorine4 ,solutions of pure hypochlorites are alkaline in reaction because of the excess of hydroxyl ions 7minimum concentration #a x #aj-d74 ,in solutions of bleach the hydrolytic action is retarded by the ,,oh' due to the free base1 and accelerated by the excess of ,h4 caused by the dissociation and partial hydrolysis of ,ca,cl#b2 the final result is determined by the relative proportions and the effect of the free base usually preponderates4 ,the addition of any substance that reduces the ,,oh' concentration enables hydrolysis to proceed to completion and affords a rational explanation of the fact that solutions of bleach1 on distillation with such weak acids as boric acid1 yield a solution of hypochlorous acid4 ,it also explains why the addition of an acid is necessary in ,bunsen's method 7vide p4 #gi7 of analysing hypochlorite solutions4 ,it has been stated that when hydrochloric acid is employed the increase in the oxidising power is due to the action of the acid upon calcium chloride but this never occurs under ordinary conditions2 weak acids such as carbonic or acetic will give practically the same result as hydrochloric acid in solutions of bleach of the strength used in water treatment4 ,the slightly higher result obtained with strong acids is due to the decomposition of chlorates4 ,the effect of dilution alone is shown by the data given below4 ,a #b per cent bleach solution1 containing very little excess base1 was diluted with distilled water and the various dilutions titrated with thiosulphate after the addition of potassium iodide4 ,in one series the solutions were titrated directly1 and after acidification in the other4 ,the results,a were as follows3 ,,hydrolysis ,,of ,,bleach ,,solution ---------------------------------------- ------------------ ,strength of ,solution4 ,grams ,bleach ,direct ,titration x #ajj ,per #ajj c4cms4 --------------------4 ,acid ,titration ---------------------------------------- ------------------ #b4j #cj4h #j4b #cd4c #j4a #da4h #j4jb #fg4e #j4jjb #ajj4j ---------------------------------------- ------------------ ,a ,corrected for the alkali produced by ,h,cl,o #b,,ki ,k,cl ,,koh ,i#b4 ,although every precaution was taken to exclude carbonic acid1 a portion of the hydrolysis was probably due to this acid1 which would remove calcium hydrate from the sphere of action and consequently alter the equilibrium4 ,the above figures are only applicable to the particular sample used2 other samples containing different excesses of base would yield different hydrolytic values4 ,the results are in agreement with the hypothesis presented and confirm the theoretical deduction that very dilute bleach solutions are completely hydrolysed if no salts are present that will dissociate and increase the ,,oh' concentration4 ,hydrolysis is reduced by caustic alkalies and alkaline carbonates1 and increased by acids and acid carbonates that reduce the ,,oh' concentration4 ,the effect of chlorides is anomalous and no adequate explanation for their action can be given at present4 ,the addition of small quantities of sodium chloride 7#j4a per cent7 increases the hydrolysis of bleach solutions but much larger quantities tend to the opposite direction4 ,the effect of these substances upon the velocity of the germicidal action of bleach solutions is in the same direction as the hydrolysing effect4#d ,sodium chloride in quantities up to #aj parts per million has a very limited effect but larger quantities 7#ij p4p4m47 increase the velocity of the reaction4 ,sodium chloride1 in the absence of hypochlorites1 was found to have no influence upon the viability of ,b4 coli in water4 ,in quantities up to approximately #e p4p4m41 sodium hydroxide has but little influence2 #e-aj p4p4m4 reduce the velocity to a marked degree1 but when the quantity of caustic is still further increased the germicidal action of the alkali commences to be appreciable and may nullify the retarding action on the hypochlorite4 ,normal carbonates tend to reduce the velocity of the germicidal action and bicarbonates to increase it4 ,sulphuric acid1 even in very small quantities 7#e p4p4m471 has a marked accelerating effect and the total effect produced is much greater than can be accounted for by the germicidal activity of the acid alone4 ,weak acids such as carbonic acid and acetic acid are also effective accelerators4 ,in one experiment a #j4ja per cent solution of bleach was found to be #dj per cent hydrolysed4 ,by passing carbonic acid gas this was increased to #ie per cent and the velocity of the germicidal action of this solution was found to be approximately #ajj per cent greater than that of the uncarbonated one4 ,norton and ,hsu#e have shown that the germicidal activity of some disinfectants is a function of the hydrogen ion concentration1 but this factor is insufficient to account for the effect of acids on bleach solutions4 ,the effect of sodium chloride on the bacteriological results1 like that on the hydrolytic constant1 is anomalous4 ,similar effects have been observed on the addition of this salt to phenol and other disinfectants4 ,the raison d'etre of the increased activity is obscure but it is possible that the salt renders the organisms more susceptible to the action of the germicide4 ,ammonia1 though decreasing the hydrogen ion concentration of bleach and other hypochlorite solutions1 markedly increases the velocity of the reaction2 chlorinated derivatives of ammonia 7chloramines71 which have a specific germicidal action1 are formed4 ,these will be discussed at length in ,chapter ,,ix1 p4 #aae4 ,rideal#f has shown that the addition of ammonia to sodium hypochlorite destroys the bleaching activity in acid solution4 ,this has been found by the author to be also true for calcium hypochlorite 7bleach74 ,if the bleaching effect is due to oxidation1 the oxidising power of hypochlorites must be considered to be destroyed by the addition of ammonia4 ,the property of oxidising organic matter in water is also destroyed2 this is well illustrated in ,table ,,ii which shows the rate of absorption of chlorine and chloramine by the ,ottawa ,river water4 ,the water used in this experiment contained #dj p4p4m4 of colour and absorbed #i4e p4p4m4 of oxygen 7#cj mins4 at #ajj deg4 ,c474 ,,table ,,ii4,a ---------------------------------------- --------------------------- ,,absorption ,,of ,,available ,,chlorine ,,at #fc deg4 ,f4 ,time of ,contact ---------------------------------------- -------- ,minutes4 ,chlorine as ,bleach4 ,chlorine as ,chloramine4 ---------------------------------------- -------------------------- ,nil4 #aj4jj #i4ih #e #f4ej #i4ih #aj #e4ia #i4ij #bj #e4ah #i4ij #dj #d4dg #i4hd #fj #c4ij #i4hd #hj #c4fe #i4hd #bj hours 4444 #i4fh ---------------------------------------- -------------------------- ,a ,results are parts per million4 ,from a consideration of these and other experiments made by the author in ,january1 #aiaf1 it became apparent that the nascent oxygen hypothesis entirely failed to explain the results obtained1 and that they must be attributed to a direct toxic action of the chlorine or chloramine4 ,dakin et al4#g arrived at a similar conclusion from a consideration of the results obtained during the use of hypochlorite solutions in the treatment of wounds by ,carrel's method of irrigation4 ,they attributed the marked beneficial action to the formation of chloramines in situ by the action of hypochlorous acid upon amino acids and proteid bodies4 ,compound chloramines 7chlorinated aminobenzoic acids7 were prepared in the laboratory and found to give excellent results in reducing wound infection4 ,later1 other compounds were prepared for the purpose of sterilising small quantities of water for the use of mobile troops 7see p4 #abh74 ,rideal#f was the first to note the strong germicidal power of chloramine and attributed the persistent germicidal activity of hypochlorites in sewage to the formation of chloramine and chloramine derivatives4 ,further evidence against the nascent oxygen theory of chlorine disinfection is to be found in the fact that such active oxidising agents as sodium1 potassium1 and hydrogen peroxides have a much lower germicidal activity than chlorine when compared on the basis of their oxygen equivalents4 ,table ,,iii shows chlorine to be approximately five times as active as potassium permanganate when compared on this basis4 ,,table ,,iii4,a--,,comparison ,,of ,,bleach ,,and ,,potassium ,,permanganate ---------------------------------------- -------- ,,bleach ,available ,chlorine ,,potassium ,contact #j4ce p4p4m4 ,,permanganate4 ,period4 ------------------------------------- ,oxygen ,equivalent4 ,parts ,per ,million4 ----------------------------------- #j4jh #j4acc #j4bff #j4djj ---------------------------------------- ------ ,nil #adj 444 444 444 #cj mins #ij #abb #aae #aaj #a hour #fh #aae #ajj #hj #a-a_/b hours #fc #ajh #ie #ge #d hours #ej #ie #hj #ej ---------------------------------------- ------ ,a ,results are ,b4 coli per #aj c4cms4 ,the germicidal activity of oxidising agents has been shown by ,novey and others to be somewhat proportional to the energy liberated during the reaction but even when this factor is taken into consideration chlorine compounds are more active than other oxidising agents4 ,hypochlorous acid is far superior to hydrogen peroxide as a germicidal agent and is as active as ozone1 which liberates a greater amount of energy4 #b;,h,cl,o #b;,h,cl ,o#b #ah1ggj calories #b;,h#b,o#b #b;,h#b,o ,o#b #df1abj calories #b,o#c #c,o#b #fj1jjj calories4 ,again1 solutions of chlorine gas and hypochlorites having the same oxidising activity1 as determined by titration with thiosulphate after the addition of potassium iodide and acid1 i4e4 contain equal amounts of available chlorine1 show approximately the same germicidal activity in water4 ,on the addition of ammonia1 the hypochlorite solutions retain their ability to liberate iodine from potassium iodide 7,wagner test7 but the property of oxidising such dyestuffs as indigo is destroyed and the germicidal activity is increased4 ,ammonia1 when added to solutions of chlorine gas1 diminishes the property of liberating iodine from potassium iodide1 the bleaching effect on dyestuffs1 and the germicidal action4 ,it is often assumed that chlorine forms hypochlorous acid on solution in water ,cl#b ,h#b,o ,h,cl,o ,h,cl but the results obtained on the addition of ammonia indicate that either very little hypochlorous acid is formed or that ammonia and hypochlorous acid do not form chloramine in the presence of hydrochloric acid4 ,when chlorine gas was treated with a #j4e per cent solution of ammonia in the proportion of #a molecule of chlorine to #a4ij-a4ie molecules of ammonia1 ,noyes and ,lyon#h found that nitrogen and nitrogen-trichloride were formed in equimolar quantities4 #ab,,nh#c #f;,cl#b ,n#b ,n,cl#c #i,,nh#d;,cl4 ,bray and ,dowell#i showed that this reaction depended upon the hydrogen ion concentration and proceeded in accordance with the following equations3 7i74 ,acid solution #d,,nh#c #c;,cl#b ,n,cl#c #c,,nh#d;,cl 7ii74 ,alkaline solution #h,,nh#c #c;,cl#b ,n#b #f,,nh#d;,cl4 ,in 7i7 with a ratio of chlorine to ammonia of #c3a by weight1 one-half of the chlorine is lost as ammonium chloride and one-half forms nitrogen trichloride1 concerning which comparatively little is known2 in 7ii7 the whole of the chlorine forms ammonium chloride1 which has no germicidal value4 ,the effect of ammonia on the germicidal action of a solution of chlorine gas is shown in the ,table ,,iv4 ,,table ,,iv4,a--,,effect ,,of ,,ammonia ,,on ,,chlorine ,,gas ,,solution ,conditions4 ,colour of water #dj p4p4m4 ,turbidity1 #e p4p4m4 ---------------------------------------- --------- ,available ,chlorine #j4bj p4p4m41 ,ammonia4 ,contact ,parts ,per ,million4 ,period4 ------------------------------------- ,nil4 #j4je #j4aj #j4bj ---------------------------------------- ------ ,nil4 #acj 444 444 444 #aj mins4 #ace #adj #acj #ace #a hour #acj #acj #abh #abj #d hours #abj #aab #aaj #aje #bd hours #abj #ade #afj #agj ---------------------------------------- ------ ,a ,results are ,b4 coli per #aj c4cms4 ,even when the ratio of ,cl3,,nh#c was #d3a by weight1 practically the same as was used in the experiments of ,noyes and ,lyon1 and ,bray and ,dowell1 quoted above1 the germicidal action was totally destroyed and the #bd-;hour results showed aftergrowths which were somewhat proportional to the amount of ammonia added4 ,this was probably due to the formation of ammonium chloride1 which provided additional nutriment for the organisms4 ,it has often been assumed that hypochlorite solutions are decomposed on addition to water containing free or half-bound carbonic acid with the production of free chlorine1 but no evidence has been adduced in support4 ,free chlorine can be separated from hypochlorous acid in aqueous solution by extraction with carbon tetrachloride and when this solvent is shaken with a carbonated hypochlorite solution it is found that only traces of chlorine are removed4 ,hypochlorous acid reacts with hydrochloric acid with the evolution of free chlorine ,h,cl,o ,h,cl ,cl#b ,h#b,o but in very dilute solution the amount of free chlorine formed is exceedingly minute4 ,jakowkin#aj has shown that this reaction does not proceed to completion and that the concentration of free chlorine can be calculated from the equation ,h,cl,o x ,h4 x ,cl' #cbj;,cl#b in which the reactions are expressed in gram molecules per litre4 ,the hydrogen ions and chlorine ions are obtained from the dissociation of carbonic acid 7,h#b;,,co#c ,h4 ,,hco#c'7 and chlorides 7,na,cl ,na4 ,cl'7 and also by the dissociation of hydrochloric acid produced by the interaction of hypochlorous acid and organic matter4 ,h,cl,o ,o ,h,cl ,h4 ,cl'4 ,if the formula of ,jakowkin can be correctly applied to solutions containing fractions of a part per million of hypochlorous acid the free chlorine liberated by the addition of #a p4p4m4 of bleach to a water low in chlorides would be of the order #aj-g-aj-h p4p4m4 ,sodium hypochlorite is probably hydrolysed in dilute solution in a manner similar to that of bleach4 #b,na,o,cl ,na,cl ,na,o,h ,h,cl,o4 ,for solutions containing equal amounts of available chlorine1 electrolytic sodium hypochlorite is more dissociated than bleach because of the absence of an excess of base1 and this1 together with the presence of sodium chloride1 accounts for the slightly higher germicidal velocity obtained4 ,the experience of pulp mills1 with bleach and electrolytic hypochlorites1 confirms this3 the latter is a much quicker bleaching agent than bleach and it is often so rapid as to make it desirable to reduce the velocity by the addition of soda ash4 ,regarding hypochlorite solutions a phenomenon of more scientific interest than of practical importance has been noted by ,breteau#ab who found that alkaline solutions of sodium hypochlorite containing #j4id per cent of available chlorine lost #c4f per cent of their titer on dilution with #hj volumes of water2 also that this loss was increased by the addition of small quantities of salt 7sodium chloride7 and more so by carbonates and bicarbonates4 ,the author has noted similar losses on diluting bleach solutions and that the loss increased on standing4 ,the loss can be explained by the decomposition of hypochlorous acid1 in the presence of light1 into hydrochloric acid and oxygen4 #b;,h,cl,o #b;,h,cl ,o#b ,,chlorine ,,water4 ,when a solution of chlorine in water is used as a germicide the chemical reactions that occur differ materially from those of hypochlorite solutions4 ,on solution in water1 hydration or solvation probably takes place with the production of heat4 ,cl#b4;,aq4 #b1fjj calories4 ,chlorine water is comparatively stable but decomposes under the influence of light in accordance with the equation ,cl#b ,h#b,o #b;,h,cl ,o2 a similar reaction occurs in the presence of organic matter or any substance capable of oxidation4 ,chlorine water contains only minute traces of hypochlorous acid and there is no evidence that the endothermic reaction ,cl#b4;,aq ,h#b,o ,h,cl,o4,aq ,h,cl4,aq -#bfjj - #fh1dfj -#bi1icj - #ci1cae - #ahae occurs in a measurable degree4 ,from thermochemical considerations hypochlorous acid and chlorine water should be about equally active as oxidising agents4 #b;,h,cl,o4,aq #b;,h,cl ,o#b #ah1ggj calories #b;,cl#b4;,aq #b;,h#b,o #b;,h,cl ,o#b #ae1cdj calories #b;,cl#b4 ,aq #b;,h#b,o #b;,h,cl ,o#b #bj1edj calories ,when a solution of chlorine or hypochlorite is added to water as a germicidal agent1 a variety of reactions occur the character of which is determined by the nature of the mineral and organic matter in the water and the type of chlorine compound added4 ,the general reactions are of three types 7#a7 oxidation of the organic matter1 7#b7 direct chlorination of the organic matter1 and 7#c7 a bactericidal action4 ,in the treatment of waters that contain appreciable amounts of organic matter almost all the chlorine is consumed in reaction 7#a7 and even with filter effluents it is probably true that oxidation accounts for the greater portion of the chlorine consumed4 ,the author has found that a dosage of #j4jb part per million of available chlorine was more effective in destroying ,b4 coli in distilled water than #j4dj p4p4m4 in a water absorbing #i4e p4p4m4 of oxygen 7#cj mins4 at #ajj deg4 ,c474 ,reaction 7#a7 can be adequately explained by the nascent oxygen hypothesis and it is this reaction that determines the dosage required for effective sterilisation4 7,see ,chap4 ,,iii47 ,very little information is available regarding reaction 7#b7 but there is little doubt that a direct chlorination of the organic matter does occur and it is more than probable that these chlorinated derivatives are largely responsible for the obnoxious tastes and odours produced in some waters4 ,it has been suggested that these were due to the formation of chloramines4 ,this view was formerly supported by the author but the chloramine treatment at ,ottawa and other places has demonstrated the inadequacy of this explanation4 ,it is true that the odour of chloramine is stronger and more pungent than that of chlorine1 but chloramine in the ,ottawa supply1 even with doses as high as #j4e part per million of available chlorine1 has caused no complaints4 ,the odour of some of the organo-chloro compounds is more penetrating and obnoxious than those of chlorine and chloramine1 and it is quite possible that some of the higher homologues of chloramine are in this class4 ,it should be noted1 however1 that some of the chloro-amido compounds prepared by ,dakin are white1 odourless1 crystalline substances4 ,practically nothing is known regarding the specific nature of the mechanism involved in reaction 7#c74 ,the hypothesis that chlorine1 and chlorine compounds1 exert a direct toxic action on the micro-organisms marks an advance in the science of water treatment but does not indicate the physiological processes involved4 ,cross and ,bevan#aa have shown that chloro-amines have a tendency to combine with nitrogenous molecules and to become fixed on cellulose2 it is therefore possible that reaction is a cytolytic one in which the chlorine attacks and partially or wholly destroys the membranous envelope of the organisms4 ,a portion of the chlorine or chlorine-compound may also penetrate the membrane and produce changes that result in the death of the organism4 ,,bibliography #a ,fischer and ,proskauer1 ,rev4 d',hyg41 #ahhd1 #f1 #eae4 #b ,warouzoff1 ,winogradoff1 and ,kolessnikoff4 ,russkaia medicina1 #ahhf1 ,nos4 #c and #cb4 #c ,race4 ,jour4 ,amer4 ,water ,works ,assoc41 #aiah1 #e1 #fc4 #d ,griffen and ,hedallen4 ,jour4 ,soc4 ,chem4 ,ind41 #aiae1 #cd1 #ecj4 #e ,norton and ,hsu4 ,jour4 ,inf4 ,dis41 #aiaf1 #ah1 #ahj4 #f ,rideal1 ,s4 ,jour4 ,roy4 ,san4 ,inst41 #aiaj1 #ca1 #cc4 #g ,dakin1 ,cohen1 ,duafresne1 and ,kenyon4 ,proc4 ,roy4 ,soc41 #aiaf1 #hi;,b1 #bcb4 #h ,noyes and ,lyon4 ,jour4 ,amer4 ,chem4 ,soc41 #aija1 #bc1 #dfj4 #i ,bray and ,dowell4 ,jour4 ,amer4 ,chem4 ,soc41 #aiag1 #ci1 #ije4 #aj ,jakowkin4 ,zeit4 f4 ,phys4 ,chim41 #ahii1 #ai1 #fac4 #aa ,cross and ,bevan4 ,jour4 ,soc4 ,chem4 ,ind41 #ahih1 #bh1 #bfj4 #ab ,breteau4 ,jour4 ,pharm4 ,chim41 #aiae1 #ab1 #bdh4 ,,chapter ,,iii ,,dosage ,the amount of chlorine required for efficient treatment is very largely determined by the amount required to satisfy the oxidisable matter present in the water4 ,many experimenters have reported results that would indicate that appreciable concentrations of chlorine are required for bactericidal action but the details of the technique1 as published1 show that the effect of the organic matter added with the test organism was not thoroughly appreciated4 ,one cubic centimetre of a culture in ordinary peptone water1 added to one litre of water1 would increase the organic content by approximately #aj parts per million1 an amount that would absorb appreciable amounts of chlorine4 ,other conditions also make it very difficult to compare the results obtained in the past3 one of these is the degree of purity set as the objective4 ,german bacteriologists added enormous numbers of the test organism and endeavoured to obtain the complete removal of the organism from such quantities as one litre of water with a contact period often as short as #aj minutes4 ,nissen1#a of the ,hygienic ,institute of ,berlin1 found that a #a3 #hjj dilution of bleach 7#dbj p4p4m4 of chlorine7 was required to destroy ,b4 typhosus in one minute and a #a3afjj dilution 7#baj p4p4m4 of chlorine7 in #aj minutes4 ,delepine#b obtained somewhat similar results by means of the thread method for testing disinfectants4 ,phelps1#c using gelatine plates for enumeration of the bacteria1 obtained a #ij per cent reduction of ,b4 typhosus in twenty minutes with #e p4p4m4 of available chlorine2 over #ii per cent reduction in one hour1 and over #ii4ii per cent reduction in #ah hours4 ,wesbrook1 ,whittaker1 and ,mohler#d tested bleach solutions with various strains of ,b4 typhosus by means of the plate method and found that the most resistant one was reduced from #bj1jjj per c4cm4 to sterility 7in #a c4cm47 by #c p4p4m4 of available chlorine in fifty minutes and that the least resistant one only required #a4j p4p4m4 with a thirty minutes' contact4 ,lederer and ,bachmann#e have reported the following results3 ,,table ,v ,,percentage ,,reduction1 #ae ,,minutes' ,,contact ---------------------------------------- ------------------------- ,,nature ,,of ,,test ,,organism4 ---------------------------------------- --------- ,available ,b4 ,b4 ,chlorine ,b4 faecalis ,b4 ,proteus ,b4 lactis ,b4 p4p4m4 cloacae4alkali-paraty- mira- enter- aero- choleroe- genes4 phosus4bilis4 itidis4 genes suis4 ---------------------------------------- ------------------- #j4a 44444 #ii4ih 44444 #bg4c 44444 44444 44444 #j4b #ii4fi #ii4ii #ii4ig #de4e #ii4hc #ii4ag #ie4h #j4c #ii4ge #ajj4jj #ajj4jj #fc4g #ii4ih #ii4ih #ajj4j #j4e #ajj4jj 44444 44444 #gb4g #ajj4jj #ajj4jj 44444 #j4g 44444 44444 44444 #fc4g 44444 44444 44444 #a4j 44444 44444 44444 #fc4g 44444 44444 44444 #c4j 44444 44444 44444 #ij4i 44444 44444 44444 #e4j 44444 44444 44444 #ij4j 44444 44444 44444 ,original number of organisms#afj1jjj #i1ejj #c1jjj #h1jjj #ahj1jjjahj1jjj #ejj per c4cm4 ---------------------------------------- ------------------- ,with the exception of ,p4 mirabilis1 which forms endospores1 all the organisms were killed 7less than #a per c4cm47 by #j4e p4p4m4 of available chlorine in fifteen minutes4 ,all these observers found that ,b4 coli1 the organism usually employed as an index of contamination1 had approximately the same degree of resistance to chlorine as ,b4 typhosus1 though ,wesbrook et al4 directed attention to the varying viability of organisms derived from different sources4 ,these experiments merely indicate the dosage required for exceptional conditions such as it is inconceivable would ever occur in water-works practice4 ,no information is available regarding the actual ,b4 typhosus content of waters that have caused epidemics of typhoid fever1 but for the present purpose it may be assumed that the extreme condition would be a pollution by fresh sewage giving a ,b4 coli content of #a1jjj per c4cm4 or #bjj times worse than the average condition that can be satisfactorily purified without overloading a filter plant 7#ejj ,b4 coli per #ajj c4cms474 ,experiments made by the author indicate that a suspension of #a1jjj ,b4 coli per c4cm4 in water1 in the absence of organic matter1 can be reduced to a #b ,b4 coli per #ajj c4cms4 standard 7the ,u4,s4 ,treasury ,standard7 by #j4a p4p4m4 of available chlorine in ten minutes at #fe deg4 ,f4 ,this experiment indicates the amount of chlorine that is required for the bactericidal action only2 such a dosage could never be used in practice to meet a pollution of this degree because of the accompanying organic matter4 ,in actual practice the author has experienced the above condition but once1 and on that occasion the ,b4 coli were derived from soil washings and not from fresh sewage4 ,the amount of chlorine required for germicidal action is small1 and the main factors that determine the dosage necessary to obtain this action are 7#a7 the content of readily oxidisable organic matter1 7#b7 the temperature of the water1 7#c7 the method of application of the chlorine and 7#d7 the contact period4 ,oxidisable ,matter4 ,the oxidisable matter may be divided into two classes 7a7 inorganic and 7b7 organic4 ,the inorganic constituents naturally found in water1 that are readily oxidisable1 are ferrous salts 7usually carbonates71 nitrites1 and sulphuretted hydrogen1 and these react quantitatively with chlorine until fully oxidised4 ,the oxygen value of chlorine is approximately one-quarter 7actually #af3 #ga7 the available chlorine content in accordance with the equation ,cl#b_/ga ,h#b,o #b;,h,cl ,o_/#af4 ,one part per million of available chlorine will oxidise #a4eh p4p4m4 of ferrous iron2 #j4aig p4p4m4 of nitrous nitrogen2 and #j4dgi p4p4m4 of sulphuretted hydrogen4 ,,table ,,vi4,a--,,effect ,,of ,,colour ,,temperature #fc deg4 ,f4 ---------------------------------------- ----------------- ,water ,a ,colour #c ,water ,b ,colour #dj ,available ,chlorine ,available ,chlorine ,contact ,period4 p4p4m4 p4p4m4 --------------------------------------- #j4b #j4b #j4d #j4e ---------------------------------------- --------------- ,nil #aid #aid #aid #aid #e minutes #aba #afe #abi #ff #a hour #g #ie #bj #a #e hours #j #d #j #j #bd hours #j #a #a #j #dh hours #j #j #j #j ---------------------------------------- --------------- ,a ,results are ,b4 coli per #aj c4cms4 of water4 ,the organic matter found in water may be derived from various substances such as urea1 amido compounds1 and cellulose2 humus bodies derived from soil washings and swamps may also be present4 ,the humus compounds of swamps and muskeg are usually associated with the characteristic colour of the water derived from these sources4 ,the effect of this coloured organic matter upon the chlorine dosage is well illustrated in ,table ,,vi4 ,in this experiment ,b4 coli was used as the test organism and the only varying factor was the organic matter4 ,to obtain the same result with a contact period of one hour at #fc deg4 ,f4 it was necessary to use about two and one-half times the amount of chlorine with a water containing #dj p4p4m4 of colour as with one practically free from colour4 ,it will be noted that water ,a1 in which the colour had been reduced to #c p4p4m4 by coagulation with aluminium sulphate1 required a greater dosage of chlorine than was necessary for bactericidal action only4 ,this was due to a residual organic content which produced none or but a trace of colour1 for although the colour had been reduced by #ib per cent the organic matter1 as measured by the oxygen absorbed test1 had only been reduced by #gj per cent4 ,the results obtained by ,harrington#f at ,montreal are in the same direction4 ,during the greater part of the year the water is obtained from the ,st4 ,lawrence river1 which is colourless and low in organic matter2 in the spring months the flood waters of the ,ottawa1 a highly coloured river1 enter the intake and necessitated a much higher dosage4 ,,chlorine ,,treatment ,,at ,,montreal ---------------------------------------- ------------------------ ,oxygen ,chlorine ,source of ,alkali-,colour4,absorbed ,required ,bacteria ,per ,cent ,supply4 nity4 7#cj p4p4m4 per c4cm4 ,removed4 mins47 ---------------------------------------- ----------------------- ,ottawa river #ae-bj #ej-gj #ad4j #a4ej #c1jjj over #ih ,st4 ,lawrence river #ij-ajj ,nil4 #j4cj #j4cj #ejj over #ii ---------------------------------------- ------------------------ ,ellms#g obtained similar results and reported that the rate at which sterilisation proceeds varies1 in a general way1 directly with the concentration of the applied available chlorine and the temperature1 and inversely as the amount of easily oxidisable matter present4 ,experience with filter plants shows the same facts1 the amount of chlorine required for the sterilisation of a filter effluent being invariably less than that necessary to purify the raw water to the same extent4 ,the effect of coloured organic matter upon the absorption of chlorine1 in the form of hypochlorite1 is shown on ,diagram ,i4 ,illustration3 ,,diagram ,i ,,effect ,,of ,,colour ,,on ,,absorption ,,of ,,chlorine ,,by ,,water ---------------------------------------- ------------------- ,value of ,k calculated from ,absorption of ,chlorine ,log7,n#a_/,n#b7 by water at #fc deg4 ,f4 ,k ----------------- t#b - t#a ------- ------- ,when t#a #j ,time of-----------------------,time of-------------------- ,contact ,colour of ,water ,contact ,colour in --------------------- in ------------------ ,minutes #c #be #dj ,minutes #c #be #dj ---------------------------------------- ------------- ,nil #aj4jj #aj4jj #aj4jj #e #i4fb #g4gj #f4ej #e #j4jjccj4jbbgj4jcgd #aj #i4da #g4jc #e4ia #aj #j4jjbfj4jaecj4jbbh #bj #i4ag #f4dj #e4ah #bj #j4jjahj4jjifj4jaij #dj #h4ie #e4hb #d4dg #dj #j4jjabj4jjegj4jjhg #fj #h4he #e4fc #c4ij #fj #j4jjjhj4jjdaj4jjfh #hj #h4hj #e4eh #c4fe #hj #j4jjjgj4jjcbj4jjef ---------------------------------------- ------------- ,the shape of the curve obtained with a colour of #dj p4p4m4 somewhat resembled that of a mono-molecular reaction and the results were calculated accordingly4 ,the mathematical expression of this law is d,n_/dt ,,kn where ,n is the concentration of the available chlorine in parts per million4 ,integrating between t#a and t#b the formula ,k log7,n#a_/,n#b7_/7t#b - t#a7 is obtained4 ,if the compound absorbing the chlorine were simple in character1 and the chlorine were present in large excess1 the value of ,k would be constant4 ,in the experiments recorded1 ,k constantly decreases1 due to the decreasing concentrations of the reacting substances and the complex nature of the organic matter4 ,the results show the effect of organic matter on the reduction of the chlorine concentration available for germicidal action and also the importance of avoiding a local excess of chlorine 7vide p4 #da74 ,an effort has been made by some observers to find a quantitative relation between the organic matter1 expressed as oxygen absorbed in parts per million1 and the chlorine required for oxidation1 but without definite result4 ,some of the results obtained are given in ,table ,,vii4 ,,table ,,vii4--,,oxygen ,,to ,,chlorine ,,ratio ---------------------------------------- ---------- ,oxygen ,absorbed ,observer4 ,ratio -----------------4 ,chlorine ,absorbed ---------------------------------------- ---------- ,rouquette #a ,bonjean #j4e ,orticoni ,less than #a ,valeski and ,elmanovitsch #j4d ,race #j4d ,theoretical #j4bb ---------------------------------------- ---------- ,the value of #j4d 7#j4ci7 obtained by the author is the average of over one hundred determinations covering a period of two years4 ,the experiments of ,zaleski and ,elmanovitsch were made with the water of the ,neva ,river4 ,the divergence in the ratios affords additional evidence in favor of reaction 7#b7 mentioned on page #bh and also shows that the chlorinated compounds are less readily oxidized than those from which they are produced4 ,heise#h has found that the amount of chlorine consumed is usually proportional to the concentration in which it is added though not necessarily a function of the concentration of the organic matter4 ,temperature4 ,the evidence regarding the effect of temperature upon the dosage required is somewhat conflicting4 ,ellms 7vide supra7 found that the velocity of the germicidal action varied directly with the temperature and this has also been the author's experience with laboratory experiments4 ,typical examples of these are given in ,tables ,,viii and ,,ix4 ,,table ,,viii4,a--,,effect ,,of ,,temperature ,,available ,,chlorine #j4d ,,part ,,per ,,million ---------------------------------------- -------- ,temperature1 degrees1 ,fahrenheit4 ,contact ,period4------------------------------- #cf #gj #ih ---------------------------------------- ------ ,nil #dbd #dbd #dbd #e minutes #cbj #bhj #bdj #a4e hours #adh #gf #ab #d4e hours #ch #ad #c #bd hours #b #j #j #dh hours #b #j #j ---------------------------------------- ------ ,a ,results are ,b4 coli per #aj c4cms4 ,,table ,,ix4,b--,,effect ,,of ,,temperature ,,available ,,chlorine #j4b ,,parts ,,per ,,million ---------------------------------------- -------- ,temperature1 degrees1 ,fahrenheit4 ,contact ,period4------------------------------- #cf #gj #ih ---------------------------------------- ------ ,nil #bdj #bdj #bdj #e minutes #bdj #bej #bce #a hour #bde #bce #aie #d hours #bae #aij #agj #bd hours #adc #acj #aae #dh hours #acj #ei #ai #gb hours 444 #bh 444 #if hours 444 #af 444 #abj hours 444 #f 444 ---------------------------------------- ------ ,b ,results are ,b4 coli per #aj c4cms4 ,the reaction velocity of a germicide is proportional to the temperature#i and the influence of temperature may be mathematically expressed by the formula ,k#a_/,k#b theta7,t#b - ,t#a71 in which ,k#a and ,k#b are the constants of the reaction at temperatures ,t#b and ,t#a1 respectively1 and theta is the temperature coefficient4 ,from the value of theta1 the velocity constant of a germicide for any temperature may be calculated from the equation ,k,t ,k#bj deg4 x theta7,t - ,t#bj deg474 ,k#a and ,k#b are obtained from the formula ,k,t log7,n#a_/,n#b7_/7t#b - t#a7 in which ,n#a - ,n#b is the number of bacteria destroyed in the interval t#b - t#a4 ,a reduction of temperature also lowers the oxidizing activity of the chlorine so that a greater concentration is available for germicidal action4 ,this is shown by the results plotted in ,diagram ,,ii4 ,illustration3 ,,diagram ,,ii ,,effect ,,of ,,temperature ,,on ,,absorption ,,of ,,chlorine ,,by ,,water ---------------------------------------- ---------------------- ,value of ,k calculated from absorption at #fc deg4 ,f4 ,absorption of ,chlorine by water containing #dj p4p4m4 ,log7,n#a_/,n#b7 of colour ,k ----------------- t#b - t#a --------------------------- ,time of,temperature of ,water------------------------------- ,contact--------------------t#bt#a t#a t#a ,minutes#cb deg4 ,f4#df deg4 ,f4#fc deg4 ,f4minutes #j #e #aj ---------------------------------------- ---------------- ,nil #aj4jj #aj4jj #aj4jj #e #h4jj #g4de #f4ej #e #j4jcgd ---- ---- #aj #g4bc #g4ji #e4ia #aj #j4jbbh #j4jjhb ---- #bj #g4jj #f4fj #e4ah #bj #j4jaij #j4jjff #j4jjeg #dj #f4db #f4je #d4dg #dj #j4jjhg #j4jjdc #j4jjdj #fj #f4bb #e4fj #c4ij #fj #j4jjfh #j4jjdj #j4jjcf #hj #f4ac #e4dj #c4fe #hj #j4jjef #j4jjcc #j4jjbi ---------------------------------------- ---------------- ,tables ,,viii and ,,ix1 however1 show that the temperature coefficient of the germicidal action has a greater effect than the reduction in the amount of chlorine absorbed and removed from the reaction4 ,the results obtained on the works scale with these waters are very different to the laboratory ones and show that more chlorine is required during the summer season than in winter4 ,the results with bleach and liquid chlorine are in the same direction 7vide ,diagrams ,,iii and ,,iv74 ,the bleach was regulated so as to maintain a constant purity1 whilst in the other case the dosage was constant with a varying ,b4 coli content4 ,in ,diagram ,,iv the ,b4 coli is plotted2 this does not represent all the factors involved as the ,b4 coli content of the treated water is also a function of that of the raw water1 but in the example given this factor is of no moment because it was comparatively constant during the period plotted 7extreme variation #hj per cent74 ,the discrepancies between the laboratory and works results cannot be easily explained4 ,the only difference in the conditions is the nature of the containing vessel4 ,glass is practically inert at all temperatures but the iron pipes1 through which the water passed before the samples were taken1 may exert an absorptive influence on the chlorine at the higher temperatures experienced during the summer months4 ,waters containing organic matter that differs much in quantity from the examples above may yield very different results and no generalisation can be made that will cover all cases4 ,an increase of temperature increases the germicidal velocity and also the rate of absorption of chlorine by the organic matter2 other factors determine which of these competitive actions predominates4 ,method of ,application 7admixture74 ,a thorough admixture of the water and chlorine is a sine qua non for successful operation4 ,this should1 if possible1 be attained by natural means1 but if there is any doubt as to the efficiency of the mixing process1 mechanical appliances should be utilised4 ,pumps1 especially centrifugal pumps1 constitute a very convenient and efficacious method of mixing the germicide and the water1 and the solutions should never be injected into the discharge pipes when it is possible to make connections with the suctions4 ,illustration3 ,,diagram ,,iii ,,effect ,,of ,,temperature ,illustration3 ,,diagram ,,iv ,,effect ,,of ,,temperature ,inefficient admixture leads to local concentration of the chlorine1 a condition which 7vide p4 #ce71 results in a wastage of the disinfectant4 ,two practical examples of this effect may be cited4 ,in one case the water was free from colour and contained very little organic matter4 ,this water was chlorinated at one plant by allowing the bleach solution to drop into one vertical limb of a syphon approximately #f1jjj feet long1 the other vertical limb being used as a suction well for the pumps which discharged into the distribution mains4 ,at the other plant the bleach solution was injected into the discharge pipe of a reciprocating pump through a pipe perforated with a number of small holes4 ,the results for two typical months are given in ,table ,x4 ,,table ,x4--,,effect ,,of ,,efficient ,,mixing ---------------------------------------- --------------- ,available ,,bacteria ,,per ,c4,,cm4 ,chlorine ----------------------- ,parts ,per ,b4 ,coli ,index ,month4 ,million4 ,raw ,treated ,water4 ,per #ajj c4cms4 ---------- ,water4---------------------------- ,a4 ,b4 ,a4 ,b4 ,a4 ,b4 ---------------------------------------- ----------- ,july #j4bj #j4be #hfd #bg #ic #j4b #h4e ,august #j4bj #j4bg #a4ajh #ab #abj #j4b #aj4b ---------------------------------------- ----------- ,a efficient mixing4 ,b inefficient mixing4 ,the results with the ,b plant were very irregular4 ,the hypochlorite and water did not mix thoroughly and1 as several suctions pipes were situated in the suction shaft1 there was no subsequent admixture in the pumps2 this also caused complaints regarding taste and odour but the complaints were localised1 and not general as would result from an overdose of solution due to irregularities at the plant4 ,the second example deals with a water containing #dj-de p4p4m4 of colour4 ,this supply was taken from the river by low-lift pumps and discharged into a header which was connected with the high-lift pumps by two intake pipes about #e1jjj feet in length4 ,during #aiad a baffled storage basin of two hours capacity was constructed and in ,june the hypochlorite was added at the inlet to this basin by means of a perforated pipe4 ,the object was to increase the contact period prior to the delivery of the water into the header4 ,the results for this month were as follows3 ,,available ,,chlorine #a4hh ,,parts ,,per ,,million ---------------------------------------- ------------------- ,,bacteria ,,per ,c4,,cm4 ,,agar4 ------------------------ ,b4 ,coli4 #c ,days at #a day at ,index #bj ,c4 #cg ,c4 ,per c4cm4 ---------------------------------------- ------------------ ,raw water #daj #ajd #j4bhj ,treated water #di #bf #j4jcf ,percentage purification #hh4b #ge4j #hg4e ---------------------------------------- ------------------ ,during ,august the point of application of the hypochlorite was changed from the inlet of the basin to the suctions of the pumps and the solution proportioned to the amount of water pumped by the starch and iodide test4 ,the average of the daily tests for this month were3 ,,available ,,chlorine #a4ee ,,parts ,,per ,,million ---------------------------------------- --------------------- ,,bacteria ,,per ,c4,,cm4 ,,agar4 ------------------------ ,b4 ,coli4 #c ,days at #a day at ,index #bj ,c4 #cg ,c4 ,per c4cm4 ---------------------------------------- ------------------ ,raw water #ddh #ajj #j4fjj ,treated water #bf #ab #j4jje ,percentage purification #ia4i #hh4j #ii4b ---------------------------------------- ------------------ ,here again thorough admixture produced better results than inefficient admixture plus a longer contact period4 ,langer#aj has also noted the effect of local concentration and found that the disinfecting action is increased by adding the bleach solution in fractions1 a cumulative effect replacing that of concentration4 ,the importance of the admixture factor was not thoroughly appreciated during the earlier periods of chlorination but later installations1 and particularly the liquid chlorine ones1 have been designed to take full advantage of it4 ,the point of application in ,american water-works practice varies considerably 7,longley#aa74 ,in #eg per cent of those cases in which it is employed as an adjunct to filtration1 it is used in the final treatment2 in #bf per cent it is used after coagulation or sedimentation and before filtration2 in the remaining #ag per cent it is applied before coagulation and filtration4 ,the report of the committee adds3 ,the data at hand do not give any reasons for the application before coagulation4 ,in general1 an effective disinfection may be secured with a smaller quantity of hypochlorite1 if it is applied after rather than before filtration4 ,it should be noted that the storage of chlorinated water in coagulating basins1 and its passage through filters1 tend to lessen tastes and odors contributed by the treatment and this fact may in some cases account for its use in this way4 ,contact ,period4 ,other things being equal1 the efficiency of the treatment will vary directly1 within certain limits1 with the contact period4 ,when a chlorinated water has to be pumped to the distribution mains directly after treatment1 the dosage must be high enough to secure the desired standard of purity within twenty to thirty minutes4 ,the chlorine is sometimes not completely absorbed in this period and may cause complaints as to tastes and odours4 ,the examples given above show that the lack of contact period can be largely compensated by ensuring proper admixture4 ,experience has amply demonstrated that there is no necessity to use heroic doses for water that is delivered for consumption almost immediately after treatment1 and that1 with proper supervision1 complaints can be almost entirely prevented4 ,the general effect of the effect of contact period is shown in ,tables ,,viii and ,,ix on page #cg4 ,another example of a coloured water is given in ,table ,,xi1 whilst ,table ,,xii shows the results obtained with a colourless water4 ,,table ,,xi4,a--,,effect ,,of ,,contact ,,period ---------------------------------------- -------- ,,chlorine1 ,,parts ,,per ,,million4 ,contact ,period4 ---------------------------- #j4cj #j4dj #j4ee #a4ba ---------------------------------------- ----- ,nil #c1hjj 444 444 444 #a minute #a1djj #abj #j #j #aj minutes #gbj #e #j #j #bj minutes #ce #j #j #j ---------------------------------------- ----- ,a ,results are ,b4 coli per #aj c4cms4 ,,table ,,xii4--,,effect ,,of ,,contact ,,period ,,available ,,chlorine #j4bg ,,part ,,per ,,million ---------------------------------------- ---------------------------- ,sampling ,point4 ,bacteria ,per c4cm4 ---------------------------------------- ---------------------------- ,average of series #e1jjj ft4 from pumping station #cjj of samples #f1jjj #bjc #g1jjj #ajc #ab1jjj #hf #ad1jjj #hg ---------------------------------------- ---------------------------- ,table ,,xiii is taken from the work of ,wesbrook et al4#d ,,table ,,xiii4,b--,,treatment ,,of ,,mississippi ,,river ,,water ,,aug4 #h1 #aiaj ---------------------------------------- ---------------------- ,,contact ,,period4 7,,temp4 #bb deg4-#bf deg4 ,c474 ,available ,cl4------------------------------------ --------- ,p4p4m4 #a ,hr4 #f ,hrs4 #cj ,mins4 #cj ,mins4 #c ,hrs4 #cj ,mins4 #bd ,hrs4 ---------------------------------------- ------------------ #j #bcj1jjj #bjj1jjj #afj1jjj #aej1jjj #adj1jjj #j4e #ad1jjj #g1djj #b1jjj #f1jjj #aa1jjj #a4j #bj #ad #agj #dej #fj1jjj #a4e #aj #f #af #de #gj1jjj #b4j #g #h #aj #ig #gj1jjj #b4e #g #ad #cj #aaf #fe1jjj #c4j #f #ab #e #ab #af1ejj ---------------------------------------- ------------------ ,b ,results are bacteria per c4cm4 ,in ,tables ,,viii1 ,,ix1 ,,xi1 and ,,xii1 the bacteria decreased constantly with increase of contact period1 but the results in ,table ,,xiii show that no advantage was to be gained by prolonging the contact beyond three hours2 after this period the bacteria commenced to increase in number and when twenty-four hours had elapsed the number approached the original4 ,this increase in the bacteria is technically known as aftergrowth and will be discussed more fully in ,chapter ,,iv4 ,the replies to queries sent out by the ,committee on ,water ,supplies of the ,american ,public ,health ,association#aa indicate that the contact period after treatment varies considerably in ,american water-works practice4 ,forty per cent of the replies indicated no storage after treatment2 #ah per cent less than one hour2 #i per cent from one to three hours2 #e per cent three to twelve hours2 #aa per cent twelve to twenty-four hours1 and #ag per cent a storage of more than twenty-four hours4 ,turbidity is usually considered to exert an effect upon the dosage required but no definite evidence has been adduced in support of this hypothesis4 ,turbidity is generally caused by the presence of very finely divided suspended matter1 usually silt or clay1 which is inert to hypochlorites4 ,the condition that produces turbidity1 however1 produces a concomitant increase in the pollution and some of the organisms are embedded in mineral or organic material that prevents access of the chlorine to the organisms which consequently survive treatment4 ,a larger concentration is required to meet these conditions but it is not necessitated by the turbidity per se4 ,effect of ,light4 ,light exerts a marked photo-chemical effect on the germicidal velocity of chlorine and hypochlorites4 ,when chlorinated water is passed through closed conduits and basins the effect of light is of course nil but in open conduits and reservoirs this factor is appreciable and reduces the necessary contact period4 ,the effect of light on laboratory experiments made with colourless glass bottles is so marked as to make it impossible to compare the results obtained on different days under different actinic conditions4 ,the following figures illustrate the effect of sunlight3 ,,effect ,,of ,,sunlight ---------------------------------------- -------------- ,,available ,,chlorine #j4ce ,p4,p4,m4 ,contact ,period4 ------------------------------------ ,exposed to ,bright ,stored in ,dark ,sunlight 7,april7 ,cupboard4 ---------------------------------------- ------------- ,nil #bae #bae #cj minutes #acj #ade #a hour #abb #acf #b-a_/b hours #fa #acj #c-a_/b hours #j #cb ---------------------------------------- ------------- ,determination of ,dosage ,required4 ,the dosage required for the treatment of a water can only be accurately determined by treating samples with various amounts of chlorine and estimating the number of bacteria and ,b4 coli after an interval of time equal to that available in practice4 ,the temperature of the water during the experiment should be the same as that of the water at the time of sampling4 ,in order to limit the range covered by the experiments the approximate dosage can be ascertained from ,diagram ,v if the amount of oxygen absorbed by the water is known4 ,this diagram is calculated on the amount of available chlorine1 present as chlorine or hypochlorite1 that will reduce the ,b4 coli content to the ,u4 ,s4 ,treasury standard 7#b ,b4 coli per #ajj c4cms47 in two hours4 ,if the oxygen absorbed values are determined by the four-hour test at #bg deg4 ,c4 they should be multiplied by two4 ,another method which has been generally adopted for military work during the war1 consists in the addition of definite volumes of a standard chlorine solution to several samples of the water and1 after a definite interval1 testing for the presence of free chlorine by the starch-iodide reaction4 ,the details of the method of ,gascard and ,laroche1 which is used by the ,french sanitary service1 have been given by ,comte4#ab ,one hundred c4cms4 of the water to be examined are placed in each of #e vessels and #a1 #b1 #c1 #d1 and #e drops of dilute ,eau de ,javelle 7#a3ajj7 are added and the contents stirred4 ,after twenty minutes1 #a c4cm4 of potassium iodide-starch reagent 7#a gram each of starch1 potassium1 iodide and crystallized sodium carbonate to #ajj c4cms47 is added and the samples again stirred4 ,the lowest dilution showing a definite blue colour is regarded as the dose required1 and the number of drops is identical with that required of the undiluted ,eau de ,javelle for #aj litres of water when the same dropping instrument is used4 ,the actual concentration represented by these dilutions depends necessarily upon the size of the drops and the strength of the undiluted ,eau de ,javelle1 but one drop per #ajj c4cms4 usually represents approximately #a p4p4m4 ,illustration3 ,,diagram ,v ,,relation ,,of ,,dosage ,,to ,,oxygen ,,absorbed ,in ,horrocks's method1 as used in the ,british army1 a standard bleach solution is added and is almost immediately followed by the zinc iodide-starch reagent4 ,the two methods were compared by ,massy1#ac who found that the ,french method gave an average result of only #j4jf m4gr4 per litre 7#j4jf p4p4m47 higher than the ,english method4 ,water in the ,gallipoli campaign required from #j4ba to #a4jf p4p4m4 as determined by both methods4 ,dienert1 ,director of the ,paris ,service for investigating drinking water1 adds #c p4p4m4 of available chlorine and allows the mixture to stand fifteen minutes after shaking2 the residual chlorine is then titrated with thiosulphate4 ,the amount absorbed is increased by #j4e p4p4m4 and in the opinion of ,dienert this dosage is correct for a contact period of three hours4 ,for military camps where a standpipe usually provides a reasonable contact period1 it has been found good practice to add sufficient chlorine to give a rich blue colour with the starch-iodide reagent and subsequently reduce the dosage gradually until the water1 after standing one hour1 gives but a faint reaction to the test reagent4 ,this method should be checked up as soon as possible by bacteriological examinations4 ,an example of this method is given in ,table ,,xiv4 ,,table ,,xiv4--,,control ,,of ,,dosage ,,by ,,starch-,,iodide ,,reaction ---------------------------------------- ----------------------------- ,starch-iodide ,,bacteria ,,on ,,agar ,,per ,c4,,cm4 ,reaction ,after ,one ---------------------------------- ,b4 ,coli ,per ,hour4 #a ,day at #cg ,c4 #b ,days at #bj ,c4 #ajj c4cms4 ---------------------------------------- ---------------------------- #jjj #dj #ae #j #jjjj #cg #ah #h #jjjjj #fh #bfh #cd #jjjjj #aae #eec #fa ,raw water #aad #fhe #hi ---------------------------------------- ---------------------------- ,the number of signs indicates the intensity of the reaction4 ,,bibliography #a ,nissen4 ,zeit4 f4 ,hyg41 #ahij1 #h1 #fb4 #b ,delepine1 ,j4 ,soc4 ,chem4 ,ind41 #aiaa1 #bi1 #acej4 #c ,phelps4 ,water ,supply ,paper ,no4 #bbj1 ,u4 ,s4 ,geo4 ,survey4 #d ,wesbrook1 ,whittaker1 and ,mohler1 ,j4 ,amer4 ,public ,health ,assoc41 #aiaa1 #a1 #abc4 #e ,lederer and ,bachmann4 ,eng4 ,rec41 #aiab1 #fe1 #cfj4 #f ,harrington4 ,j4 ,amer4 ,waterworks ,assoc41 #aiad1 #a1 #dch4 #g ,ellms4 ,eng4 ,rec41 #aiaa1 #fc1 #dgb4 #h ,heise4 ,philippine ,jour4 ,sci41 #aiag1 #ab1 ,a1 #ag-cd4 #i ,norton and ,hsu1 ,jour4 ,inf4 ,dis41 #aiaf1 #ah1 #ahj4 #aj ,langer4 ,zeit4 f4 ,hyg41 #aiaf1 #ha1 #bif4 #aa ,longley4 ,j4 ,amer4 ,public ,health ,assoc41 #aiae1 #e1 #ibj4 #ab ,comte4 ,j4 ,pharm4 ,chim41 #aiaf1 #ad1 #bfa4 #ac ,massy4 ,j4 ,pharm4 ,chim41 #aiag1 #ae1 #bji4 ,,chapter ,,iv ,,bacteria ,,surviving ,,chlorination ,a disinfectant is usually described as a substance capable of destroying bacteria and other micro-organisms1 and an antiseptic as one that restrains or retards their growth or reproduction4 ,this distinction is entirely arbitrary as the ability of a substance to kill organisms or merely inhibit their growth depends upon the concentration employed4 ,chlorine and hypochlorites1 even in minute doses1 exert a toxic effect that is sufficient to produce death in organisms but when still smaller concentrations are employed the toxic effect is transient and the reproductive faculty may be entirely regained4 ,the enumeration of bacteria by means of solid media depends upon the ability of the organism to reproduce at such a rate as to produce a visible colony within the period of incubation and any substance that prevents the growth of a visible colony is classified as a disinfectant2 if on further incubation the bacterial count approximates that of the untreated sample the added substance has acted mainly as an antiseptic4 ,in practice no substance acts entirely as an antiseptic as the organisms present have varying degrees of resistance and the less viable ones are killed by doses that are only antiseptic to the more resistant ones4 ,an example of an antiseptic effect followed by a mild disinfectant action1 caused by small doses of bleach is shown in ,table ,,xv4 ,in this experiment the water designated as control was from the same source as the treated water4 ,in order to make the bacterial count in this water approximately the same as in the treated water1 the original count was reduced by diluting the sample with water from the same source1 sterilised by boiling1 and afterwards reaerated with sterile air4 ,,table ,,xv4,a--,,antiseptic ,,effect ,,of ,,chlorine ,sample treated with #j4a part per million of available chlorine4 ---------------------------------------- ------------------------------ ,,ratio ,,of ,,plated4 ,,incubation ,,period1 ,,days4 ,,bacterial ,,counts4 ---------------------------------------- ----------------------- ,time4 ,day4 #b #c #d #e #f #b3d #b3e #b3f ,days4,days4,days4 ---------------------------------------- ----------------------- #aa a4m4 #a #ebj #idj #a1cej #b1cfj #b1ghja3b4fa3d4ea3e4c #ab noon #a #cij #ggj #a1jhj #b1jdj #b1cbj #b4h #e4b #e4h #b p4m4 #a #ahg #bfj #fij #a1hdj #b1jhj #c4g #i4i #af4d #d p4m4 #a #ia #acj #bhj #gfj #hdj #c4a #h4c #i4b #aj a4m4 #b #db #abj #fgj #ibj 444 #ae4i #bb4 444 #aj a4m4 #c #cbj #a1baj #c1ejj 444 444 #aj4i 444 444 #aj a4m4 #d #h1gjj #ad1bjj #bf1jjj 444 444 #b4i 444 444 ---------------------------------------- ----------------------- ,,control4 ,,no ,,chlorine ,,added ---------------------------------------- ------------------------------ ,,ratio ,,of ,,plated4 ,,incubation ,,period1 ,,days4 ,,bacterial ,,counts4 ---------------------------------------- ----------------------- ,time4 ,day4 #b #c #d #e #f #b3d #b3e #b3f ,days4,days4,days4 ---------------------------------------- ----------------------- #aa a4m4 #a #aba #ahd #bhe liquid 444#a3b4da3444 444 #ab noon #a #aae #aga #bbc #chj #cib #a4ia3c4ba3c4b #b p4m4 #a #aji #aeb #bba #cfb #cge #b4j #c4c #c4d #d p4m4 #a #aba #age #bea #daj #dae #b4a #c4d #c4d #aj a4m4 #b #f1bjj #h1ejj #h1hjj #h1ijj liquid #a4d #a4d 444 #aj a4m4 #c #dbe1jjjfej1jjjfgj1jjj liquid 444 #a4e 444 444 ---------------------------------------- ----------------------- ,,original ,,sample4 ,,untreated ,,and ,,undiluted ---------------------------------------- ----------------------- #aa a4m4 #a #iae #a1daj #a1fcj #b1aej #c1bjja3b4ba3b4ha3c4e ---------------------------------------- ----------------------- ,a ,results are bacteria per c4cm4 ,table ,,xvi shows the effect of a concentration of #a4j p4p4m4 of chlorine2 the hypochlorite at this concentration acted almost entirely as a germicide or disinfectant4 ,,table ,,xvi4,a--,,effect ,,of ,,chlorine ,,as ,a ,,disinfectant ,,available ,,chlorine #a4j ,p4,p4,m4 ---------------------------------------- ----- ,,plated4 ,,incubation ,,period1 ,,days4 ---------------------------------------- ,time4 ,day4 #b #c #d #e #f ---------------------------------------- #aa a4m4 #a #b #e #g #h #aj #ab noon #a #a #a #b #b #d #b p4m4 #a #j #j #j #b #b #d p4m4 #a #a #b #b #f #f #aj a4m4 #b #j #j #j #a 44 #aj a4m4 #c #j #j #j 44 44 #aj a4m4 #d #e #ac #af 44 44 #aj a4m4 #e #gi #aff 44 44 44 ,untreated water 44 #iaea1daja1fhjb1aejc1bjj ---------------------------------------- ,a ,results are bacteria per c4cm4 ,table ,,xv shows a recovery of the anabolic functions after treatment with #j4a p4p4m4 of chlorine but since this was obtained by plating on such a suitable medium as nutrient gelatine1 it is probable that reproduction in water having a low organic content would be still further diminished4 ,this is indicated by the results obtained4 ,there is no evidence of any marked difference in the resistance of ordinary water bacteria to chlorine and these are the first to be affected by the added germicide4 ,the common intestinal organisms are also very susceptible to destruction by chlorine and there is considerable evidence that ,b4 ,coli is slightly more susceptible than many of the vegetative forms usually found in water4 ,the specific organisms causing the water-borne diseases1 typhoid fever and cholera1 are1 on the average1 not more resistant than ,b4 coli4 ,the spore-forming bacteria usually found in water are those of the subtilis group1 derived largely from soil washings1 and ,b4 enteritidis sporogenes1 from sewage and manure4 ,the spores of these organisms are very resistant and survive all ordinary concentrations4 ,wesbrook et al4#a found that #c p4p4m4 of available chlorine had little effect on a spore-forming bacillus isolated from the ,mississippi water and the author has obtained similar results with ,b4 subtilis4 ,thomas1#b during the chlorination of the ,bethlehem1 ,pa41 supply1 found four organisms that survived a concentration of #b p4p4m4 of available chlorine3 ,bact4 aerophilum1 ,b4 cuticularis1 and ,b4 subtilis1 all spore formers and ,m4 agilis4 ,in practice no attempt is made1 except in special cases1 to destroy the spore-bearing organisms as they have no sanitary significance and the concentration of chlorine required for their destruction would cause complaints as to tastes and odours if the excess of chlorine were not removed4 ,such doses are unnecessary and result in waste of material4 ,it is found that1 when the dose is sufficient to eliminate the ,b4 coli group from #be-ej c4cms4 of water1 the majority of the residual bacteria are of the spore-bearing type4 ,smeeton#c has investigated the bacteria surviving in the ,croton supply of ,new ,york ,city after treatment with #j4e p4p4m4 of available chlorine as bleach4 ,table ,,xvii gives the results obtained4 ,the organisms of the ,b4 subtilis group outnumbered all the others1 #ff 7#fb4h per cent7 belonging to this group alone4 ,this group contained ,b4 subtilis--,cohn 7#cf strains71 ,b4 tumescens--,chester 7#ae strains7 ,b4 ruminatus--,chester 7#ac strains71 and ,b4 simplex--,chester #aijd1 7#b strains74 ,three of the four coccus forms were classified as ,m4 luteus4 ,no intestinal forms were found4 ,clark and ,de ,gage#d in #aiaj directed attention to the fact that the bacterial counts1 made at #cg deg4 ,c4 on chlorinated samples1 were often much greater than the counts obtained at room temperature4 ,this phenomenon of reversed ratios between counts at the two temperatures1 they stated1 has been occasionally observed with natural water1 but a study of the record of many thousands of samples shows that the percentage of such samples is very small1 not over #c-e per cent4444 ,on the other hand #bj-be per cent4 of samples treated with calcium hypochlorite show higher counts at body temperature than at room temperature4 ,clark and ,de ,gage were unable to state the true significance of this phenomenon but were of the opinion that it was not due to larger percentages of spore-forming bacteria in the treated samples4 ,other observers1 on the contrary1 have invariably found the spore-formers to be more resistant to chlorine and thermophylic in type4 ,,table ,,xvii4--,,organisms ,,surviving ,,treatment ,,new ,,york 7,,smeeton7 ---------------------------------------- ----------------------------- ,morphology ,spore ,gelatine ,reaction in ,formation ,liquefaction ,litmus ,milk ---------------------------------------- ---------- ,bacilli4,cocci4 ,pos4 ,neg4 ,pos4 ,neg4 ,pos4 ,neg4 ---------------------------------------- ------------------------- ,no4 of strains #ajj #e #hi #af #fh #cg #ih #g ,per cent4 #ie4b #d4g #hd4g #ae4b #fd4g #ce4b #ic4c #f4f ,indol ,acid ,reduction ,inhibition ,production ,production of by ,gentian in ,glucose ,nitrates ,violet ---------------------------------------- ---------- ,pos4 ,neg4 ,pos4 ,neg4 ,pos4 ,neg4 ,pos4 ,neg4 ---------------------------------------- ------------------------- ,no4 of strains #ge #cj #fa #dd #dj #fe #ih #g ,per cent4 #ga4d #bh4e #eh #da4i #ch #fa4i #ic4c #f4f ---------------------------------------- ------------------------- ,the removal of intestinal forms is1 of course1 merely a relative one and when large quantities of treated water are tested their presence can be detected4 ,the author1 in #aiae1 made a number of experiments to ascertain whether the ,b4 coli found after chlorination were more resistant to chlorine than the original culture4 ,the strains surviving treatment with comparatively large doses were fished into lactose broth and subjected to a second treatment1 the process being repeated several times4 ,the velocity of the germicidal reaction with the strains varied somewhat1 but not always in the same direction1 and the variations were not greater than were found in control experiments on the original culture4 ,no evidence was obtained that the surviving strains were in any way more resistant to chlorine than the original strain2 in considering the results it should be borne in mind that the surviving strains were cultivated twice on media free from chlorine before again being subjected to chlorination4 ,a number of the strains that survived several treatments were cultivated in lactose broth and the acidity determined quantitatively4 ,all the cultures produced less acid than the original culture1 and the average was materially less than the original4 ,these results point to a diminution of the bio-chemical activity by action of the chlorine4 ,a point of perhaps more scientific interest than practical utility is the relative proportion of the various types of ,b4 coli found before and after treatment with chlorine4 ,the author1 in #aiad1 commenced the differentiation of the types by means of dulcite and saccharose and obtained the results shown in ,table ,,xviii4 ,these figures are calculated from several hundreds of strains4 ,although there is a slight difference in the relative proportions of the types found at ,ottawa and ,baltimore1 both sets of results show definitely that there is no difference in the resistance of the various types to chlorination4 ,aftergrowths4 ,in ,tables ,,xiii 7p4 #dd7 and ,,xv 7p4 #ea71 it will be noticed that1 after the preliminary germicidal action has subsided1 a second phase occurs in which there is a rapid growth of organisms4 ,this is usually known as aftergrowth4 ,when the contact period between chlorination and consumption is short1 the reaction does not proceed beyond the first phase1 but when the treated water is stored in service reservoirs the second phase may ensue4 ,at one purification plant1 where the service reservoirs are of large capacity1 the aftergrowths amounted to #bj1jjj bacteria per c4cm4 although the water left the purification plant with a bacterial count usually lower than #ej per c4cm4 ,,table ,,xviii4--,,types ,,of ,b4 ,,coli ,,surviving ,,chlorination ---------------------------------------- -------------------------- ,,percentage ,,of ,,organisms4 ---------------------------------------- ----- ,b4 coli ,b4 coli ,b4 lactis ,b4 acidi communis communior aerogenes lactici ---------------------------------------- - ,chlo- ,chlo- ,chlo- ,chlo- ,raw4 ri- ,raw4 ri- ,raw4 ri- ,raw4 ri- nated nated nated nated ---------------------------------------- ------------------- ,ottawa1 #aiad #e #d #dj #dh #dd #cf #aa #ab ,ottawa1 #aiae #h #h #ej #df #cd #ca #h #ae ,baltimore1 #aiac;,a #aa #ad #cc #be #ce #ca #ba #cj ---------------------------------------- ------------------- ,a ,thomas and ,sandman4#e ,regarding the nature of this aftergrowth1 there has been a considerable difference of opinion3 some regard it as the result of the multiplication of a resistant minority of practically all the species of organisms present in the untreated water2 others1 that it is partially due to the organisms being merely slugged or doped1 i4e4 are in a state of suspended animation1 and afterwards resume their anabolic functions2 whilst others believe that with the correct dosage of chlorine1 only spore-forming organisms escape destruction and that the aftergrowth is the result of these cells again becoming vegetative4 ,the aftergrowths obtained under the usual working conditions vary according to the dosage of chlorine employed1 and none of the above hypotheses alone provides an adequate explanation4 ,when the dosage is small1 a small number of active organisms1 in addition to the spore bearers1 will escape destruction1 and others will suffer a reduction of reproductive capacity4 ,the flora of the aftergrowth in this case will only differ from the original flora by the elimination of a majority of the organisms that are most susceptible to the action of chlorine and the weaker members of other species of greater average resistance4 ,as the dose is increased these factors become relatively less important until a stage is reached when only the most resistant cells1 the spores1 remain4 ,the resultant aftergrowth must necessarily be almost entirely composed of spore-bearing organisms4 ,a small number of the most resistant members of non-sporulating organisms may also be present but they will1 in the majority of instances1 form a very small minority4 ,this is the condition that usually obtains in practice and it is necessary to consider whether the aftergrowth may have any sanitary significance4 ,concerning the secondary development of ,b4 coli1 the usual index of pollution1 there is but little information4 ,h4 ,e4 ,jordon#f reported that1 of #bja samples1 #ba gave a positive ,b4 coli reaction immediately after treatment1 #ci after standing for twenty-four hours1 and #db after forty-eight hours4 ,these increases were confined to the warm months1 the cold months actually showing a decrease4 ,the following figures1 taken from the author's routine tests for #aiac and #aiad1 show a similar tendency1 but an analysis of the results by months did not show that this was confined to the warm season4 ,the sequence of the results from left to right1 in the following ,table1 is in the same order as the contact period4 ,approximately #bij samples were taken at each sampling point4 ,at station ,no4 #b the germicidal action was still proceeding but at ,no4 #e1 representing an outlying section of the city1 the increase in the ,b4 coli content is very apparent4 ,during #aiae and #aiaf the author endeavoured to duplicate these results under laboratory conditions and entirely failed4 ,these experiments1 which were made with the same materials as were in use at the city chlorination plant1 but in glass containers1 were usually only carried to a forty-eight hours contact1 as this was the extreme limit for the city mains2 one1 however1 was prolonged to five days4 ,many experiments were made under varying conditions1 with similar results4 ,typical examples are given in ,tables ,,vi1 ,,viii and ,,ix on pages #cc and #cg4 ,,table ,,xix4--,,aftergrowths ,,of ,b4 ,,coli ,,percentage ,,of ,,samples ,,showing ,b4 ,,coli ,,in #aj ,c4,,cms4 --------------------------------------- ,,sampling ,,point ,,no4 ------------------------------ #a #b #c #d #e ------------------------------ #aiac #ae4b #ad4d #af4c #af4h #bf4h #aiad #g4j #e4g #f4j 4444 #aa4f ----------------------------------- ,in every case there was persistent diminution in the number of ,b4 coli with increase of contact period4 ,determination of the bacterial count on nutrient agar showed that1 in several experiments1 the aftergrowth had commenced1 and in some instances there was evidence that the second cycle was partially complete i4e4 the number had reached a maximum and then commenced to decline4 ,the time required for the completion of the two cycles1 comprising the first reduction caused by the chlorine1 the increase or aftergrowth1 and the final reduction due to lack of suitable food material1 is dependent upon several factors of which the dosage and temperature are the most important4 ,with a small dosage the germicidal period is short and the second phase is quickly reached2 with large doses1 the second phase is not reached in forty-eight hours2 the higher the temperature the quicker is the action and the development of the aftergrowth4 ,these statements refer only to the bacteria capable of development on nutrient agar4 ,the ,b4 coli group behaved differently and persistently diminished in every case4 ,if ,b4 typhosus acts in a similar manner to ,b4 coli1 the laboratory experiments show that aftergrowths are of no sanitary significance and can safely be ignored1 but as the results obtained in practice are contradictory to the laboratory ones1 the matter must be regarded as sub judice until more definite evidence is available4 ,it is common knowledge that samples of water from dead ends of distribution mains show high counts and much larger quantities of ,b4 coli than the water delivered to the mains4 ,this is another phase of aftergrowth problem that often causes complaints and can only be eliminated by blowing off the mains frequently or by providing circulation by connecting up the dead ends4 ,one extreme case of this description might be cited4 ,a small service was taken off the main at the extreme edge of the city to supply a ,musketry ,school two miles away and was only in use for a few months in the summer season4 ,this service pipe delivered water containing ,b4 coli in a considerable percentage of the #aj c4cm4 samples and in a few instances in #a c4cm41 although the water delivered to the city mains never exceeded #b ,b4 coli per #ajj c4cms4 and averaged about one-tenth that quantity4 ,no epidemiological records of the effect of this water are available because it was put through a ,forbes steriliser before consumption4 ,in some instances the rate of development of the organisms after chlorination is greater than in the same water stored under similar conditions4 ,this is especially noticeable in the presence of organic matter and has been ascribed to the action of the chlorine on the organic matter with the production of other compounds that are available as food material for the organisms4 ,houston1 during the treatment of prefiltered water ,lincoln in #aije1 found that although the removal of ,b4 coli and other organisms growing at #cg deg4 ,c4 was satisfactory1 there was almost invariably an increase in the bacteria growing on gelatine at #bj deg4 ,c4 ,this was ascribed to the action mentioned above and the chemical results supported this view1 more organic matter being found in the filter effluents than in the prefiltered water4 ,rideal's experiments with sewage at ,guildford indicate that a similar action may occur in contact beds4 ,the addition of bleach to the prefiltered water at ,yonkers also resulted in an increased count and in these instances the aftergrowths are due to a disturbance of the equilibrium by the action of the chlorine on the zooglea and other organic matter invariably found in ripe filters4 ,similar results can be produced by the addition of chlorinated water to small experimental sand filters4 ,this is shown by the results in ,tables ,,xx and ,,xxi4 ,,table ,,xx4--,,aftergrowths ,,in ,,sand ---------------------------------------- -------------------- ,bacteria ,per ,available ,gram of ,typical ,b4 coli ,,free ,,chlorine ,chlorine in ,sand ,after ,after #bd ,hours4 ,,after #bd ,,hrs4 ,water p4p4m4 ---------------------------------------- - #ajj #aj #a #j4a,without ,after #c ,hrs4#bd ,hrs4,gr4,gr4,gr4,gr4 ,acidification4 ---------------------------------------- --------------- ,nil #ab1jjj #ba1jjj - - - #c4j #hjaad1jjj - - - - - - #e4j #ejaej1jjj - - - - - - #g4j #bebad1jjj - - - - - - #aj4j #bfejj1jjj - - - - - - ---------------------------------------- --------------- ,,table ,,xxi4--,,aftergrowths ,,in ,,sand ---------------------------------------- ------- ,,bacteria ,,per ,,gram ,,of ,,sand ,,after ,available in ------------------------------- ,water p4p4m4 #c ,hours4 #bd ,hours4 #dh ,hours4 ---------------------------------------- ----- ,nil #gj1jjj 44444 44444 #j4a #g1bjj #bj1djj #ab1hjj #j4c #e1bdj #f1djj #aa1bjj #j4e #e1abj #d1gjj #aj1hjj #a4j #a1ajj #h1hjj #bj1djj ---------------------------------------- ----- ,it is observable that the effect of small doses was comparatively small and transient2 large doses of bleach reduced the bacteria very materially but the reduction was not maintained and the subsequent increase was abnormally rapid4 ,,bibliography #a ,wesbrook1 ,whittaker and ,mohler4 ,j4 ,amer4 ,pub4 ,health ,assoc41 #aiaa1 #a1 #abc4 #b ,thomas4 ,jour4 ,ind4 and ,eng4 ,chem41 #aiad1 #f1 #edh4 #c ,smeeton4 ,jour4 of ,bact41 #aiag1 #b1 #ceh4 #d ,clark and ,de ,gage4 ,rpt4 ,mass4 ,b4 of ,h41 #aiaj1 p4 #cai4 #e ,thomas and ,sandman4 ,j4 ,ind4 and ,eng4 ,chem41 #aiad1 #f1 #fch4 #f ,jordan1 ,h4 ,e4 ,eng4 ,record1 #aiae1 ,may #ag4 ,,chapter ,v ,,complaints ,the complaints that have been made against chlorinated water since the practice was commenced have been very diversified in character and can be numbered by the legion and although some have been justifiable1 the great majority has been unsubstantiated and must be ascribed to auto-suggestion4 ,almost every one who has had charge of chlorination plants has noted the latter phenomenon1 for in some instances complaints have been made following the publication of the information that chlorination was to be commenced but antecedent to its actual operation1 and in others when for some reason or another1 the chlorination plant has been temporarily stopped4 ,similar observations have been made in laboratory experiments when independent observers have been requested to detect the chlorinated waters from an equal number of treated and untreated waters4 ,such observers are wrong in the majority of the waters which they designate as treated ones if the dosage is not in excess of that required for satisfactory purification4 ,one amusing example of auto-suggestion was experienced by the author some years ago4 ,during a ceremonial visit to the waterworks1 the ,mayor and several civic representatives happened to visit a hypochlorite plant that was built on a pier over the river and which had no ostensible connection with the city mains4 ,one of the party expressed a desire for a drink of good river water without any hypochlorite in it and was served with water from the plant supply by an assistant engineer of the waterworks department4 ,the water was consumed by all with great relish and as it was being finished1 the writer entered the plant and was invited to join them in the enjoyment of this dopeless water2 on asking where it had been obtained he was astonished to hear that it was from a tap which was supplied with the ordinary chlorinated water of the city4 ,on many occasions1 complaints are justifiable and should be carefully investigated instead of1 as is often the case1 being attributed to auto-suggestion4 ,the time and energy that are often devoted to endeavouring to persuade water consumers that their complaints are without foundation1 can better be utilised in so improving the chlorination process as to eliminate tastes and odours4 ,all complaints should be carefully investigated and a record kept for future reference1 for the cause1 although not manifest at the time1 may be discovered later4 ,the records then provide valuable corroborative evidence4 ,the nature of the complaints against chlorinated water is very diversified and includes imparting foreign tastes and odours1 causing colic1 killing fish and birds1 the extraction of abnormal amounts of tannin from tea1 the destruction of plants and flowers1 the corrosion of water pipes1 and that horses and other animals refuse to drink it4 ,tastes and ,odours4 ,when an excess of hypochlorite or liquid chlorine is added to a water it imparts a sharp pungent odour and acid taste1 characteristic of chlorine1 that render it offensive to the nose and palate4 ,in some instances the presence of chlorine compounds is not obtrusive when the temperature of the water is low but becomes so when the temperature is raised4 ,it is especially observable when the faucets of hot water services are first opened and the chlorine is carried off as a vapour by the other gases liberated by the reduction in pressure4 ,for this reason the complaints regarding hot water are relatively more numerous and sometimes constitute the whole of the complaints4 ,in cold water containing appreciable quantities of mineral salts the hypochlorites and hypochlorous acid might not be entirely dissociated2 they may become more hydrolysed with an increase in temperature and finally broken down under the influence of the carbonic acid liberated from the bicarbonates by heat4 ,chlorine also forms chlorinated organic compounds by action on the organic matter present in water and some of the objectionable tastes and odours of chlorinated waters have been attributed to this agency4 ,some observers have stated that chloramines were amongst the chloro-organo compounds produced but the author's experience with the ,ottawa supply has demonstrated that simple chloramine 7,,nh#b;,cl7 can be successfully employed for water treatment without causing complaints4 ,it was suggested on page #bh that some of the higher chloro-amines might be the cause of some complaints but at present there is no definite information regarding the formation of these compounds in water and all such hypotheses are little more than conjectures4 ,letton#a has reported that at ,trenton1 in #aiaa1 when the water of the ,delaware ,river was first treated1 the dosage was as high as #a4b p4p4m4 of available chlorine and although chemical tests showed the absence of free chlorine1 the water had an extremely disagreeable taste which was especially noticeable in the hot water4 ,the conclusion was reached that the taste and odour were not those of chlorine1 but were due to some complex chemical change brought about by the action of the chlorine on the organic matter present in the water4 ,the waters that require the most accurate adjustment of chlorine dosage1 if complaints are to be avoided1 are those containing very small amounts of organic matter4 ,the margin between the dosage required for the attainment of a satisfactory degree of bacteriological purity and that which may cause complaints is usually very small1 often less than #be per cent1 with the waters of the ,great ,lakes and many filter effluents4 ,on the other hand1 coloured waters containing large amounts of organic matter can be treated with an excess of chlorine without causing tastes and odours4 ,the author found that the addition of #a4e p4p4m4 of available chlorine to the ,ottawa ,river water did not cause complaints although only #j4h to #j4i p4p4m4 were usually required for satisfactory purification4 ,harrington of ,montreal has had a similar experience with this water4 ,the presence of traces of foreign substances in water sometimes produces chlorinated derivatives having repugnant tastes and odours4 ,creosote and tar oils have caused an odour somewhat resembling that of iodoform and industrial wastes have also produced complaints4 ,the substitution of chlorine gas 7liquid chlorine7 for bleach solutions has apparently eliminated tastes and odours in some cases but this may be due to a more perfect control over the dosage rather than to any property of the bleach per se4 ,in some instances the sludge from bleach plants has caused complaints by producing an excessive concentration of chlorine during the period of its discharge4 ,this occurred in ,ottawa on several occasions before it was discovered and corrected4 ,when the sludge in the storage tanks reached the discharge valve it was customary to wash out the tank and discharge the sludge into the river4 ,the operators opened the wash out valves to the full extent and the sludge and liquor were discharged into the river about #gj feet away from the inlet to the sedimentation basin and on the downstream side of it4 ,a portion of the hypochlorite was almost invariably carried into the basin and increased the dosage4 ,this condition was remedied by carrying the sludge drain farther down stream and insisting upon the sludge being discharged at a slower rate4 ,kienle#b has reported similar occurrences at ,chicago4 ,the hypochlorite was applied at the intake cribs situated a considerable distance off shore4 ,the direction of the wind often necessitated holding the sludge for a considerable length of time but occasionally it was found impossible to await favourable conditions with the result that the wind and wave action carried a portion of the sludge back into the crib and down into the shaft and tunnel4 ,the temperature of the water at the time of treatment is another factor bearing on the production of tastes and odours4 ,when the temperature is low1 water absorbs relatively less chlorine 7vide ,diagram ,no4 ,,ii1 page #ch7 in the same period of time with the consequence that1 if the dosage is kept constant1 more chlorine is present in the free condition4 ,at ,milwaukee 7,kienle7#b with a dosage of #j4bd p4p4m4 of available chlorine 7as bleach7 no complaints were received during the spring1 summer1 and autumn seasons but when the temperature reached #dj deg4 ,f41 they were compelled to reduce the chlorine to #j4ab p4p4m4 in order to prevent objectionable tastes and odours in the tap waters4 ,abnormal conditions such as freshets1 and storms1 sometimes cause complaints regarding tastes and odours4 ,adams#c found that the complaints in ,toronto usually accompanied a change in the direction of the wind1 a sustained east wind being the one most productive of trouble4 ,the exact cause for this could not be ascertained but it was usually found that there was an accompanying increase in the number of microscopical organisms 7plankton7 present in the raw water4 ,freshets usually increase the bacterial contamination and necessitate an increased dosage which may cause complaints4 ,complaints as to tastes and odours can be best avoided by ensuring regularity of dosage1 perfect admixture1 and storage of the treated water for a reasonable period4 ,these factors are discussed in detail elsewhere4 ,colic4 ,although claims have been made that the consumption of chlorinated water has produced colic no corroborative evidence has been adduced and the symptoms have probably been due to some other cause4 ,dilute solutions of chlorine have been used as intestinal antiseptics in the treatment of typhoid fever without producing irritation of the mucous lining and the usual dose for this treatment is one grain of chlorine4 ,before taking a medicinal dose of chlorine #adj gallons of water containing #j4a p4p4m4 would have to be consumed1 a quantity greater than is ordinarily drunk in a year4 ,chlorine and hypochlorites are destructive and irritant to skin and it is possible that hot chlorinated water has1 in some instances1 a similar effect4 ,it is inconceivable that the addition of minute traces of bleach or chlorine to water should cause it to extract abnormal amounts of tannin from tea but it is possible that free chlorine1 when present1 acts upon the tea extractives and produces compounds having obnoxious tastes and odours4 ,tannin to the ordinary tea drinker represents the disagreeable portion of the tea and an obnoxious taste in tea brewed with chlorinated water would consequently be ascribed to the extraction of abnormal quantities of tannin4 ,almost all waterworks departments using chlorination have received complaints to the effect that the water had killed fish and small birds4 ,there is usually no evidence that the loss was due to chlorinated water but it is generally impossible to convince the owners that the process of water treatment was not the cause4 ,many continuous physiological tests have been made of the effect of chlorinated water on small fish and have shown that the concentration used in water treatment is without effect4 ,the author kept a tank of minnows in one of the pumping stations for months without loss although the tank was continuously supplied with water that had been treated but a few seconds previously4 ,the bleach solution was discharged into the suction of the pumps and the water for the fish test was taken from the discharge header4 ,it has been found on many occasions that fish are extremely susceptible to chlorine and hypochlorites4 ,this knowledge has been sometimes used for such nefarious purposes as fish poaching1 a few pounds of bleach in a small stream being a simple and most effective method of killing all the fish which are then carried down stream into a convenient net4 ,chlorinated sewage effluents have also been known to destroy the fish life of the stream into which they were discharged4 ,the opinion of fish culturists as to the action of chlorinated waters upon fish eggs in hatcheries is almost unanimously to the effect that it is a destructive one4 ,fish eggs are extremely sensitive to chlorine and hypochlorous acid and very few will survive in a water containing #j4a p4p4m4 of free chlorine4 ,the ,department of ,fisheries of the ,dominion of ,canada has informed the author that free chlorine in the water had a marked adverse effect on the hatching of the eggs of ,atlantic salmon1 ,great ,lake trout1 pickerel1 and whitefish1 but no effect was noticed when free chlorine was absent4 ,the ,department has1 however1 decided to remove all the hatcheries to localities where water that does not require chlorination can be obtained4 ,the effect of chlorinated water upon seeds1 plants1 and flowers has been investigated by the ,dominion ,department of ,agriculture and ,dr4 ,gussow 7,dominion ,botanist7 and ,dr4 ,shutt 7,agricultural ,chemist7 who were in charge of the work1 have reported that water treated with hypochlorite caused no apparent injury to carnations and hybrid roses4 ,six varieties of wheat seed1 after soaking in freshly prepared hypochlorite solutions 7#j4je to #aj parts per million of available chlorine7 were all sown on the same day4 ,germination was found to be uniform throughout and no effect of the chlorine was observed either as regards the rate of germination or the development of the young plants4 ,experiments on barley and oats produced similar results4 ,radishes1 turnips1 cucumbers1 and beans also showed no retardation in development after treatment with chlorinated water4 ,these experiments were conducted with solutions of bleach in distilled water1 but identical results were obtained in a later series when the treated city supply 7,ottawa7 was used4 ,the results proved conclusively that statements alleging damage to plants1 flowers1 and seeds by the hypochlorite treatment of water are unfounded and do not merit the slightest consideration4 ,corrosion of ,pipes4 ,chlorinated water1 it has been alleged on many occasions1 causes rapid corrosion of galvanised iron water services and especially of the water tubes of boilers1 water heaters1 etc4 ,when bleach is used for water treatment1 a slight increase in the hardness is produced but as this is mostly due to calcium chloride1 there is no corresponding increase in the salts that form a protective coating4 ,the presence of traces of calcium chloride and chloro-organic compounds might tend to increase the corrosive properties of a water but this increase is probably so small as to be negligible4 ,if pipe corrosion is considered by the carbonic acid hypothesis1 the use of bleach should tend to reduce it because bleach contains an excess of base that combines with a portion of the free carbonic acid4 ,the results of routine tests for free carbonic acid made on the raw and treated waters at ,ottawa are as follows3 ---------------------------------------- -------------- ,,carbonic ,,acid4 ,,parts ,,per ,,million ,year4 --------------------- ,nature of ,treatment4 ,raw ,water4,chlorinated ,water4 ---------------------------------------- ------------- #aiae #a4dd #a4da ,bleach #aiaf #j4ib #j4he ,bleach #aiag #j4hd #j4ha ,bleach first four months ,chloramine during last eight months ---------------------------------------- ------------- ,these figures shown that the hypochlorite treatment produced a small but definite decrease in the carbonic acid content and should1 caeteris paribus1 tend to reduce and not increase corrosion4 ,if the corrosion of pipes is considered according to the electrolytic theory1 a slight increase1 due to an increased electrical conductivity1 might be anticipated4 ,the effect of the addition of hypochlorite upon the electrical conductivity of distilled water and the ,ottawa ,river water is shown in ,diagram ,,vi4 ,illustration3 ,,diagram ,,vi ,effect of ,calcium ,hypochlorite on ,electrical ,conductivity ,with the concentrations of hypochlorite ordinarily used in water treatment it is inconceivable that the slight increase in the electrical conductivity has any practical significance at low temperatures4 ,the conductivity increases rapidly1 however1 with increase of temperature and any increment due to chlorination might produce a slight appreciable effect at temperatures approaching the boiling-point of water4 ,liquid chlorine does not increase the conductivity to the same extent as an equivalent quantity of hypochlorite but it increases the carbonic acid content in proportion to the dosage used4 ,the author investigated the action of hypochlorite on galvanised pipes in #aiad and was unable to detect any definite corrosion with normal concentrations of chlorine4 ,the experiments were made with #b-;inch pipes and an examination of the first consignment received showed that1 although the galvanising on the outside was perfect1 the inner coat was very inferior3 in some parts there was an excess of zinc that broke away on scraping whilst in others the iron pipe was bare4 ,a committee of the ,pittsburg ,board of ,trade1 appointed to investigate complaints as to pipe corrosion1 reported in #aiag that they were largely due to inferior qualities of pipes and not to the method of water purification employed 7slow sand filtration and chlorination74 ,the effect of chlorination on the plumbo-solvency of water was investigated in #aijd by ,houston who found that chlorine1 as chloros1 in amounts between one and ten parts per million1 did not appreciably increase the plumbo-solvent action of either unfiltered or filtered water4 ,similar results were obtained by the author with the ,toronto supply3 raw lake water1 filtered water1 and water treated with #j4be and #j4ej p4p4m4 of chlorine1 all dissolved the same quantity of lead in twenty-four hours4 ,the amount in each case was too small to be of any significance4 ,,bibliography #a ,letton4 ,j4 ,amer4 ,waterworks ,assoc41 #aiae1 #b1 #fhh4 #b ,kienle4 ,j4 ,amer4 ,waterworks ,assoc41 #aiae1 #b1 #fij4 #c ,adams4 ,j4 ,amer4 ,pub4 ,health ,assoc41 #aiaf1 #f1 #hfg4 ,,chapter ,,vi ,,bleach ,,treatment ,the treatment of water with bleach alone has been largely supplanted by the liquid chlorine process but the following details will be of use on meeting conditions for which liquid chlorine cannot be used and also for the preparation of the hypochlorite solution required in the chloramine process4 ,the essential features of a bleach installation are the solution or mixing tanks1 storage tanks1 piping system1 discharge orifice or weir1 and sludge drain4 ,bleach is usually sent out by the manufacturers in sheet steel drums1 #ci inches high and #bi-a_/b inches in diameter1 which contain about #ad cu4 ft4 of bleach and weigh approximately #gej pounds gross and #fij pounds net4 ,it can be most economically purchased in car lots and if the consumption warrants this procedure storage should be provided for about #gj drums or rather more than one car load4 ,according to ,hooker#a bleach loses #a per cent of available chlorine per month in hot seasons and #j4c per cent in cold ones so that it is advisable to carry as little stock as possible during hot weather4 ,hot weather also causes a further loss by accelerating the action of the bleach on the drum which rapidly disintegrates and cannot be handled4 ,bleach can often be purchased more cheaply in hot weather but such a policy is a short sighted one unless it is required for immediate use4 ,the general design of a hypochlorite plant is largely determined by the capacity but in all cases an effort should be made to avoid complicated details which may appear advantageous in the drafting office but do not stand up in actual practice4 ,many metals rapidly develop a protective coating on immersion in bleach solution but if this is removed by friction1 rapid erosion ensues2 bearing metallic surfaces should be reduced to a minimum4 ,mixing ,tanks4 ,all tanks1 whether mixing or storage1 should be constructed of concrete and painted with two coats of asphalt4 ,experience has shown that wooden tanks are not suitable4 ,the author has used pine1 oak1 and cypress tanks but all were rapidly leached by the hypochlorite and ultimately had to be lined with concrete4 ,there is a considerable variation in the concentration of bleach solution made in mixing tanks at various works4 ,some operators use about one gallon of water per pound of bleach and mix the two to a cream by wooden paddles1 revolving on a central axis1 for #a-b hours2 the paddles are then stopped and the cream run out into the storage tanks and diluted to the required strength by passing water through the mixing tank4 ,there are two objections to this method3 7#a7 the addition of small quantities of water to bleach tends to gelatinisation which may protect lumps from the further action of water and 7#b7 a stratification of the solution occurs in the storage tank unless agitation is used4 ,gelatinisation causes loss of available chlorine and stratification causes irregular dosage unless corrected by agitation1 which necessitates power4 ,other operators mix the bleach and water to the final concentration in the mixing tank and discharge the contents into the storage tank1 the intermittent process being repeated until the storage tank is full4 ,gelatinisation is avoided by using a low original concentration and as all batches are of equal density no stratification is produced4 ,at ,ottawa the bleach is crushed and1 after weighing1 dumped into a circular concrete tank provided with a hinged wooden lid4 ,the stirring arrangement consists of a bronze shaft on which an aluminium impeller is fixed which revolves in an iron tube set slightly above the bottom of the tank 7see ,fig4 #a74 ,after the requisite amount of water has been added the motor connected to the bronze shaft is started and the mixture pumped for #ae-bj minutes2 without waiting for the sludge to settle the contents are discharged into the storage tank and the operation repeated until the tank is full4 ,the piping between the mixing and storage tanks is of galvanised iron of generous dimension so as to compensate for incrustation4 ,the pipes are straight and are provided with crosses at every change of direction to enable excessive incrustation to be removed4 ,the valves should be made of hard rubber or special bronze2 if brass valves are used they will probably require renewing every twelve months4 ,illustration3 ,fig4 #a4--,mixing ,tank for ,bleach4 ,the concentration of solution necessarily depends upon local conditions but it is usually advisable to keep it below #b4e per cent of bleach1 which is equivalent to #j4he per cent of available chlorine4 ,storage ,tanks4 ,these should be built of reinforced concrete and painted inside with asphalt1 which should be periodically renewed to prevent the solution seeping through to the reinforcement4 ,at least two tanks should be provided so that one may be filled and allowed to settle before being put in operation4 ,the hypochlorite discharge pipe is usually #f-i inches from the bottom to permit the collection of sludge1 which is run off when it reaches the elevation of the hypochlorite discharge4 ,the sludge drain1 which opens into the bottom of the tank1 is usually a #d- or #f-;inch cast-iron pipe1 with suitable gate valve1 which discharges into a common drain made of clay pipe4 ,the storage tanks should be provided with either glass gauges or float indicators to enable the orifice discharge to be checked up at periodical intervals4 ,regulation of ,dosage4 ,the discharge of the hypochlorite solution is usually regulated either by maintaining a constant head on an orifice of variable dimension or by varying the head on an orifice of fixed dimension4 ,the weir principle may also be used but it is not so well adapted for hypochlorite as for other chemicals4 ,in the constant head method1 the head is maintained by a bronze valve connected to a float made of glass or tinned copper4 ,in many cases the orifice is a rectangular slot in a brass plate and is adjusted by means of a brass slide operated by a micrometer screw4 ,brass plates are not very suitable as they become corroded and so reduce the size of the orifice2 if the incrustation is removed the orifice will discharge more than the calibration indicates4 ,needle valves are unsuitable for similar reasons4 ,an example of an orifice feed box of the constant head type is shown in ,fig4 #b4 ,a vertically arranged hard-rubber pipe passes though a hard rubber stuffing box in the bottom of the tank and has one or more orifices near its upper end4 ,the area of the submerged portions of the orifices is controlled by the hand wheel which is connected with the threaded stem of the pipe4 ,the stem has sixteen threads per inch1 and one revolution of the wheel will submerge the orifices one-sixteenth of an inch4 ,the extent to which the orifices are submerged is indicated on the dial fixed to the side of the tank4 ,illustration3 ,,fig4 #b4--;,dosage ,tank4 ,fig4 #c shows the regulating mechanism of another apparatus of the constant head type4 ,the orifice consists of a circular slot in a hard rubber disc and is regulated by means of a hand wheel which operates a hard rubber slide4 ,illustration3 ,,fig4 #c4--,orifice ,controlling ,device4 ,the general arrangement of one of the variable head types is shown in ,fig4 #d4 ,a constant head is maintained on the valve ,v by a float and cock operating in a lead- or porcelain-lined tank4 ,the circular tapered orifice ,o1 cut in glass1 is situated in the flanged end of the iron casting ,c and the head1 indicated on the gauge glass1 is regulated by valve ,v4 ,this arrangement is simple and reasonably accurate4 ,the orifice may show slight incrustation after being in service for some time but it can be easily cleaned by means of a test-tube brush or a small swab moistened with acid2 a wire or rod tends to break the edge of the conical orifice and should not be used4 ,the volume of solution discharged by orifices of various dimensions is shown in ,diagram ,,xv1 page #adi4 ,diagram ,,xvi1 page #adi1 facilitates the calculation of the number of pounds of bleach required for any dosage4 ,illustration3 ,,fig4 #d4--,variable ,head ,dosage ,box4 ,the solution discharged from the orifice box is carried to the point of application either in galvanised iron pipes of generous dimension or in rubber hose4 ,pumps may be used for raising the solution to a higher elevation but unless special material is used in their construction they corrode rapidly and cannot be kept in service4 ,whenever possible1 a water injector should be used as it does not corrode and assists in maintaining the delivery pipes free from sludge4 ,all delivery pipes should be duplicated and blown out regularly by water under pressure2 they should also be protected from frost4 ,the adjustment of the hypochlorite dosage can be automatically regulated in plants where the flow of the water to be treated is measured by a ,venturi meter or other suitable appliance4 ,various devices have been suggested and used but1 in general1 they are not so successful as automatic regulators for liquid chlorine on account of the presence of sludge particles which tend to diminish the area of the orifice4 ,for small plants1 barrels have often been used as solution and storage vessels with1 in some instances1 fairly successful results4 ,the bleach process1 however1 cannot be recommended for small installations because the chemical control necessary for successful operation is usually not available4 ,one drum of bleach may suffice for several months operation and as the powder gradually loses strength1 the dosage constantly diminishes and may jeopardise the safety of the supply4 ,liquid chlorine machines are much more suitable than hypochlorite installations for supplies having no chemical control4 ,bleach is being very extensively used for the sterilisation of the water used by the allied troops in ,france4 ,the water supplies on the ,british front are all more or less subject to pollution and it is consequently necessary1 to ensure adequate protection1 to chlorinate all supplies with bleach4 ,other forms of chlorine have been tried but have not proved successful near the firing lines4 ,the details of the technique employed cannot be given but it may be stated that the concentration of chlorine employed is always more than sufficient and that residual tastes and odours are regarded as secondary considerations4 ,treated water is always tested by the starch-iodide method and a bacteriological examination is frequently made by mobile laboratories4 ,control of ,hypochlorite ,plants4 ,if efficient operation and regular dosage is to be obtained1 it is necessary that hypochlorite plants should be controlled by a trained chemist4 ,good results are occasionally obtained without such control but in every plant circumstances arise at some period or another which only a chemist is qualified to deal with4 ,the points that require consideration are 7#a7 the composition of the bleach2 7#b7 concentration of available chlorine in the prepared solutions2 and 7#c7 chemical tests for free chlorine in the treated water4 7#a7 ,composition of ,bleach4 ,each drum of bleach should be sampled and analysed before use4 ,the sample is obtained by cutting out the head of the drum and removing a vertical section by means of a special sampling tube or a piece of half-inch iron pipe which is forced to the bottom of the drum with a boring motion and then removed2 the core is then forced out by means of a rod1 mixed1 and quartered down to the required size4 ,for analysis weigh out #e grms4 on a balance sensitive to #j4ja grm4 and grind in a mortar with #ej-gj c4cms4 of water2 wash into a #bej c4cm4 flask and make the volume up to #bej c4cms42 shake4 ,after allowing the sludge to settle remove #aj c4cms4 by means of a pipette and titrate by one of the following methods3 ,bunsen's ,method4 ,add #aj c4cms4 of a #e per cent solution of potassium iodide and #j4e c4cm4 glacial acetic acid and titrate with sodium thiosulphate 7#bd4h grms4 of the ,c4,p4 crystalline salt and #a c4cm4 of chloroform per litre7 using a starch solution as indicator4 ,each cubic centimetre of thiosulphate used #a4gee per cent of available chlorine 7#a c4cm4 ,n_/#aj sodium thiosulphate #j4jjcee grm4 available chlorine74 ,penot's ,method4 ,dilute the hypochlorite solution with #ae c4cms4 of water and titrate with a solution of ,n_/#aj sodium arsenite using starch-iodide paper as an external indicator4 ,each c4cm4 of solution used #a4gee per cent of available chlorine 7#a c4cm4 #j4jjcee grm4 available chlorine74 ,the use of an external indicator makes this process a slow one and to overcome this objection ,mohr proposed the addition of an excess of sodium arsenite solution and then titrating with ,n_/#aj iodine solution after adding a few drops of starch solution4 ,griffen and ,hedallen#b compared these three methods and found that ,penot's method and ,mohr's modification of that method gave results which were #j4f per cent lower than those obtained by ,bunsen's method4 ,for a separate estimation of the chlorine present as chloride1 chlorate1 and hypochlorite the method given in ,sutton's ,volumetric ,analysis1 #ajth edition1 page #agh1 should be followed4 ,storage ,liquor4 ,this is tested by any of the above methods4 ,it has been proposed to determine the strength of the bleach solution by the use of a hydrometer but the results are not sufficiently accurate and the method cannot be recommended4 ,if bleach is properly broken up and thoroughly agitated in the mixing tank at least #ie per cent of the available chlorine should be extracted4 ,the efficiency of the extraction process is checked by comparing the tests of the storage liquor with those of the dry bleach and each batch of liquor should be tested daily4 ,it is sometimes advisable to take two samples from each tank1 one soon after a tank has been put into operation1 and a second sample at the end of the run4 ,considerable differences are occasionally found between these samples and are due1 either to inadequate agitation of the liquor in the storage tank1 or inefficient mixing in the mixing tank4 ,if the results are irregular the former is the more probable cause but if the second sample is invariably stronger the mixing tank operations should be investigated4 ,the increased concentration of the second sample is due to unextracted bleach passing out of the mixing tank and gradually becoming leached as the tank contents are run off4 ,if the bleach is lumpy and is not subsequently broken up1 losses are almost inevitable4 ,hale#c found that during the period when the ,new ,york ,city supply was being treated with bleach it was necessary to constantly check the operations of the labourers by frequent samples4 ,during one week about #ie per cent of the chlorine added was actually applied1 the second week it dropped to #he per cent4 and the third week to #ge per cent4 ,whenever a poor run is called to the attention of the labourers1 results improve4 ,by taking two samples daily from each tank discharged the author has been able to obtain an average annual efficiency on the ,ottawa plant of #id per cent41 i4e4 the solutions contained #id per cent4 of the available chlorine contained in the bleach4 ,in making such checks it is necessary to keep a careful account of the stock of bleach to prevent labourers adding a few extra pounds of bleach to compensate for losses4 ,sludge forms an appreciable but unavoidable source of loss of material4 ,when the sludge reaches the outlet of the hypochlorite pipe the sludge must be run to waste2 otherwise it will pass over and tend to choke the dosage control apparatus4 ,if the sludge is run into the same body of water that forms the source of supply1 it must be discharged very slowly to prevent a possibility of over dosage and damage to fish life4 ,with proper control1 sludge losses can easily be kept under #b per cent4 and often under #a per cent4 ,the greatest source of unavoidable loss in hypochlorite plants is from deterioration of the bleach during storage2 in warm climates this loss may exceed #aj per cent4 ,in ,ottawa where high temperatures are only experienced during the summer months the loss from this cause has averaged from #g-h per cent4 on the bleach stored during that period4 ,detection and ,estimation of ,free ,chlorine4 ,the oldest and probably the best known test for free chlorine in water is the ,wagner test1 made by adding a few drops of potassium iodide and starch2 the presence of chlorine is indicated by a deep rich blue colouration that is proportional in intensity to the quantity of chlorine present4 ,when this test is used as a colorimetric method for the estimation of chlorine several difficulties are encountered2 the intensity of the colour produced by the majority of treated waters gradually diminishes and the loss is usually more rapid than in the standards made up with distilled water2 a different result is obtained if the solutions are acidified and the results vary with different acids1 acetic acid yielding a much lower result than a mineral acid such as hydrochloric acid2 in the presence of acid the colouration usually intensifies on standing1 whereas the standard intensifies but little4 ,the difference caused by the addition of acid is imperfectly understood but it is obvious that the chlorine set free by the acid cannot be present in the free state2 it is probably in a semi-labile condition loosely attached to organic compounds4 ,whether this semi-labile chlorine is available for germicidal action is at present not definitely known but it has been noted by several observers that the germicidal action proceeds after the free chlorine reaction has disappeared4 ,the method used by the author for the estimation of free chlorine is as follows3 place #ejj c4cms4 of the sample in a stoppered bottle1 add #a c4cm4 of #e per cent ,,ki solution1 #b drops of conc4 ,h,cl and #a c4cm4 of starch solution and titrate with ,n_/#ajjj sodium thiosulphate until colourless4 ,the difficulty introduced by the opalescence of the liquid is overcome by pouring portions of the liquid into two ,nessler tubes and adding a drop of thiosulphate solution to one and noting if any reduction of colour occurs on shaking2 if the intensity of the colour is diminished1 the contents of both tubes are poured back into the bottle and titrated until no further colour removal1 as shown by the tubes1 can be obtained4 ,one c4cm4 of ,n_/#ajjj sodium thiosulphate #j4jg p4p4m4 of available chlorine when #ejj c4cms4 of water are used4 ,adams#d has employed the colorimetric method of estimating the colour obtained after the addition of dilute ,h#b,,so#d1 ,,ki1 and starch but used standard solutions of dyes for comparison4 ,the standards were prepared from mixtures of ,brilliant ,mill ,green ,s and ,cardinal ,red ,j and were made up weekly4 ,phelps found that ortho-tolidine in acetic acid solution produced an intense yellow colouration with free chlorine and suggested the use of this reagent as a qualitative test for chlorine4 ,ellms and ,hauser#e developed this process into a quantitative one and substituted hydrochloric acid for acetic acid as a solvent4 ,one c4cm4 of the reagent 7#a gram of pure o-tolidine dissolved in #a litre of #aj per cent of hydrochloric acid7 is added to #ajj c4cms4 of the sample in a ,nessler tube and the colour compared after five minutes with permanent standards made up with mixtures of potassium bichromate and copper sulphate4 ,this method was adopted as the official standard method of the ,american ,public ,health ,association2 the details are given in the ,appendix 7p4 #adg74 ,the author has found that this method gives excellent results except for coloured waters4 ,the colouring matter in many waters diminishes in intensity on the addition of acids and is somewhat similar in tint to that produced by addition of o-tolidine4 ,if the reaction is used qualitatively on coloured treated water and a comparison made with the untreated sample1 a negative result1 due to the reduction in colour produced by the acid being greater than the increase caused by the reagent1 might be obtained when traces of free chlorine are present4 ,similar difficulties are encountered when quantitative comparisons are made against permanent standards4 ,benzidine 7,wallis#f7 has also been suggested for the detection of free chlorine4 ,on adding this reagent a blue colouration is produced but on stirring it rapidly changes to a bright yellow which is proportional in intensity to the amount of free chlorine present4 ,ellms and ,hauser#e investigated benzidine in #aiac and found it to be inferior to o-tolidine as a test reagent for free chlorine4 ,le,roy#g has proposed the use of hexamethyltripara-aminotriphenylmethane for detecting and estimating free chlorine4 ,on the addition of a hydrochloric acid solution of this compound to a sample containing free chlorine a violet colouration is produced that can be matched in the usual way with standards4 ,it is stated that #j4jc p4p4m4 of free chlorine gives a distinct colouration and that the reagent reacts very slowly with nitrites and is quite unaffected by hydrogen peroxide4 ,the starch-iodide and o-tolidine reactions are affected by oxidising agents or reducible substances2 nitrites and ferric salts are the compounds that are most likely to interfere and ,ellms and ,hauser#e have found that these bodies do not affect the o-tolidine reaction to the same extent as the starch-iodide reaction4 ,very small quantities of nitrites 7#j4jc p4p4m4 of ,n7 and ferric salts 7#j4b p4p4m4 ,fe7 give a blue colouration with the starch-iodide reagent and for this reason it is always advisable1 whenever possible1 to make a control test on the untreated water4 ,nitrites are oxidised by free chlorine and consequently do not interfere with the estimation of it by the thiosulphate method2 the influence of ferric salts can be overcome by substituting #c c4cms4 of #be per cent phosphoric acid for hydrochloric acid 7,winkler#h74 ,an electrical instrument called a chlorometer has been devised by ,e4 ,k4 ,rideal and ,evans#i for the estimation of free chlorine4 ,the diagrammatic sketch1 reproduced in ,fig4 #e1 shows the general construction of the apparatus4 ,when water containing no free chlorine passes through the copper tube1 hydrogen is liberated on the platinum rod by the electrolytic solution pressure of the copper and an electric current is generated2 a polarizing action follows and the flow of current ceases4 ,when free chlorine is present it combines with the hydrogen as produced and so enables more copper to dissolve and produces a permanent flow of current4 ,the current produced is a function of the depolarizing action1 i4e4 of the free chlorine1 and is indicated by the current meter which is graduated in parts per million of available chlorine4 ,the usual range of instrument is #e p4p4m4 and each division of the scale is equal to one-tenth of one part per million4 ,only strong oxidisers1 such as chlorine1 ozone1 and permanganates1 which have a great affinity for hydrogen1 are able to produce a permanent current2 ferric chloride and other weak oxidisers do not affect the indicator4 ,illustration3 ,,fig4 #e4--,rideal-,evans ,chlorometer4 ,,costs ,cost of ,construction4 ,according to the replies received by the ,committee on ,water ,supplies of the ,american ,public ,health ,association#aj the total cost of equipment for disinfection varies widely and bears no apparent relation to the capacity of the equipment4 ,this is due to the temporary nature of the plants erected in many cities and the necessity of erecting expensive structures in others4 ,the cost of construction varies also in different localities4 ,the cost of equipping hypochlorite plants with standard concrete tanks and dosage regulators would be more uniform and for capacities between #aj and #ej million gallons per day would approximate #ae to #ej per million gallons4 ,the operating cost of bleach plants shows similar wide variations4 ,in some cases the labour required for mixing and supervision can be obtained without extra cost whilst in others the labour charge exceeds the cost of hypochlorite4 ,the price of bleach has shown violent fluctuations during the last three years 7see ,diagram ,,ix1 page #abe7 but is now 7#aiah7 comparatively steady at #b4be to #b4ge per #ajj pounds4 ,assuming that #cc4c per cent of available chlorine can be extracted1 each pound of chlorine costs #f4ge-g4be cents as compared with #ae-be cents for liquid chlorine4 ,the fixed charges on the capital expenditures together with the labour and incidental charges almost invariably make the total cost of operation of a straight bleach plant higher than that of a liquid chlorine plant4 ,the tendency during the last four years has been to substitute liquid chlorine for hypochlorite and the majority of the plants are now of the former type4 ,,antichlors ,substances used for the removal of excess chlorine are usually known as antichlors and those that have been most frequently employed are sodium bisulphite1 ,na,h,s,o#c1 and sodium thiosulphate ,na#b,s#b,o#c4 ,the reactions with chlorine are3 7i7 ,na,h,s,o#c ,cl#b ,h#b,o ,na,h,s,o#d #b;,h,cl4 7ii7 ,na#b,s#b,o#c ,cl#b ,na#b,s#d,o#f #b,na,cl4 ,sodium bisulphite is a very efficient antichlor1 only #a4df parts being required to remove #a part of chlorine1 but owing to its instability the action is uncertain4 ,sodium thiosulphate is a comparatively stable cheap salt1 containing #e molecules of water of crystallization1 ,na#b,s#b,o#c 4 #e;,h#b,o but #g parts are necessary to remove #a part by weight of chlorine4 ,antichlors are used as aqueous solutions and the dosage controlled in the same manner as for bleach solutions4 ,the action is an instantaneous one and it is consequently necessary that the germicidal action should be complete before the antichlor is added4 ,filters1 containing solid materials capable of absorbing free chlorine1 have also been used for removing the excess of the germicidal reagent4 ,iron borings and aluminium were used experimentally by ,thresh#aa but the process was not commercially developed4 ,the ,de ,chlor filter1 in which carbon is the active substance1 has been installed at several water works in ,england 7,reading1 ,exeter1 ,aldershot7 with apparently successful results4 ,the ,reading experimental installation1 described by ,walker1#ab consisted of a steel drum1 #h feet #c inches in width1 the top and bottom being domed4 ,in the upper portion1 #aj feet #i inches in depth1 provision was made for thorough admixture of the bleach solution and water and a subsequent storage of thirty minutes4 ,the lower section of the filter was divided into three compartments1 the first and last of which contained graded silica2 the middle compartment was filled with a layer 7#bj inches deep7 of specially prepared granulated charcoal or carbon4 ,the filter was operated under pressure and passed an average of #aib1jjj ,imp4 gallons per day1 the rate being #cb1jjj ,imp4 gallons per square yard per day4 ,water from the pre-filters 7polarite and sand7 was treated with bleach to give a concentration of #a p4p4m4 of available chlorine and passed through the ,de ,chlor filter4 ,the average bacteriological results obtained during the first six months operation were as follows3 ,bacteria ,per c4cm4 ,b4 coli ,index ,gelatine #c ,days at #bj deg4 ,c4 ,per #ajj c4cms4 ,raw river water #f1gge #fjj ,water from pre-filters #egi #aai ,water from ,de ,chlor filter #cc ,nil ,free chlorine could not be detected by chemical tests in the filtered water which was also free from abnormal tastes and odours4 ,it is stated that the carbon has to be removed and revivified periodically4 ,the filter was washed about once per week1 the wash water being only one-tenth of one per cent4 ,the experimental filter was operated for nearly two years before being removed to permit the erection of larger units having a total capacity of one million ,imp4 gallons per day4 ,,bibliography #a ,hooker4 ,chloride of ,lime in ,sanitation1 ,new ,york1 #aiac4 #b ,griffen and ,hedallen4 ,j4 ,soc4 ,chem4 ,ind41 #aiae1 #cd1 #ecj4 #c ,hale4 ,proc4 ,n4 ,j4 ,san4 ,assoc41 #aiad4 #d ,adams4 ,j4 ,amer4 ,pub4 ,health ,assoc41 #aiaf1 #f1 #hfg4 #e ,ellms and ,hauser4 ,j4 ,ind4 and ,eng4 ,chem41 #aiac1 #e1 #iae and #ajcj2 ibid41 #aiad1 #f1 #eec4 #f ,wallis4 ,ind4 ,jour4 ,med4 ,res41 #aiag1 #d1 #gig4 #g ,le ,roy4 ,comptes rend41 #aiaf1 #afc1 #bbf4 #h ,winkler4 ,zeit4 angew4 ,chem41 #aiae1 #bh1 #bb4 #i3 ,rideal1 ,e4 ,k4 and ,evans4 ,analyst1 #aiac1 #ch1 #cec4 #aj ,j4 ,amer4 ,pub4 ,health ,assoc4 #aiae1 #e1 #iba4 #aa ,thresh4 ,internat4 ,congress ,appl4 ,chem41 #aijh4 #ab ,walker4 ,jour4 ,roy4 ,inst4 ,pub4 ,health1 ,jan41 #aiaa4 ,,chapter ,,vii ,,liquid ,,chlorine ,the use of liquefied chlorine for the disinfection of water was first proposed by ,lieutenant ,nesfield#a of the ,indian ,medical ,service4 ,he stated that3 ,it occurred to me that chlorine gas might be found satisfactory 444 if suitable means could be found for using it4444 ,the next important question was how to render the gas portable4 ,this might be accomplished in two ways3 ,by liquefying it1 and storing it in lead-lined iron vessels1 having a jet with a very fine capillary canal1 and fitted with a tap or a screw cap4 ,the tap is turned on1 and the cylinder placed in the amount of water required4 ,the chlorine bubbles out1 and in ten to fifteen minutes the water is absolutely safe1 and has only to be rendered tasteless by the addition of sodium sulphite made into a cake or tablet4444 ,the cylinders could1 of course1 be refilled4 ,this method would be of use on a large scale1 as for service water carts4 ,the first practical demonstration of the possibilities of this method was made by ,major ,darnall#b of the ,medical ,corps1 ,united ,states ,army1 in #aiaj4 ,chlorine was taken from steel cylinders and passed through automatic reducing valves which provided a uniform flow of gas for the water requiring treatment4 ,a uniform flow of water was maintained through the mixing pipe and so secured a uniform dosage4 ,this apparatus might be considered as the forerunner of the various commercial types of machines that were developed later and which are being so extensively used at the present time4 ,a working model1 having a capacity of #ejj gallons per hour1 was erected at ,fort ,myer1 ,va41 and was operated on water that had been treated with alum but had received no further purification4 ,despite the presence of the flocculated organic matter1 satisfactory purification was obtained with #j4e to #a4j p4p4m4 of available chlorine and no taste or odour was imparted to the supply4 ,from the results obtained at ,fort ,myer1 and ,washington1 ,d4,c41 ,darnall concluded that ,in general1 it may be said that with an average unfiltered river water such as that of the ,potomac1 about one-half of one part 7by weight7 of chlorine gas per million of water will be required4 ,for clear lake waters three-tenths to four-tenths of a part per million will be sufficient4 ,a ,board of ,officers of the ,war ,department examined the results and reported 7,june1 #aiaa7 ,that the apparatus is as efficient as purification by ozone or hypochlorite and is more reliable in operation than either4444 ,that it could be installed at a very low cost and that the cost of operation would be very slight4 ,in ,june1 #aiab1 ,ornstein experimented with chlorine gas1 obtained from the liquefied gas in cylinders1 for sewage and water disinfection but his method differed from ,darnall's in first dissolving the gas in water and feeding the solution to the liquid to be treated4 ,kienle#c made experiments at ,wilmington1 ,del41 in ,november1 #aiab1 and obtained a constant flow of gas by means of high- and low-pressure valves2 the gas was dissolved in water in an absorption tower and afterwards fed to the water to be treated4 ,van ,loan and ,thomas of ,philadelphia experimented with liquid chlorine on a large scale at the ,belmont ,filter ,plant in ,september1 #aiab4 ,the chlorine was fed into the filtered water basin in the gaseous state and the quantity was regulated by the loss in weight of the containers4 ,the dosage was approximately #j4ad p4p4m4 7,west#d74 ,jackson1 of ,brooklyn1 made similar experiments about the same time at the ,ridgewood ,reservoir1 ,brooklyn1 and his type of apparatus was shortly afterwards put on the market as the ,leavitt-,jackson ,liquid ,chlorine ,machine4 ,the regulation of the flow in this machine was determined by the loss in weight of the gas cylinder which was suspended from a sensitive scale beam4 ,by moving the counterbalancing weight on the beam at a constant rate1 a uniform flow of gas was obtained1 the area of the orifice being kept constant by the equilibrium in the balance operating controlling valves through a system of levers4 ,this type of apparatus was tried at several places but it was found that the adjustment of the regulating mechanism was too sensitive and produced considerable irregularities in the flow of gas4 ,the type used by ,ornstein and ,kienle were combined and commercially developed by the ,electric ,bleaching ,gas ,co4 of ,new ,york4,a ,in this combined type the gas was collected from one or more cylinders by means of a manifold which delivered it to the regulating mechanism at the pressure indicated by a gauge attached to the inlet pipe4 ,beyond this gauge were two pressure-regulating devices1 the first being used primarily to reduce the initial pressure to about #ae pounds per square inch1 and the second for controlling the pressure through a range sufficient to give the desired discharge of gas4 ,the gas from the second regulator passed through an orifice in a plate at a pressure indicated by a suitable gauge which was calibrated in terms of weight of chlorine per unit of time4 ,the gas1 on leaving the regulating apparatus1 passed up an absorption tower of hard rubber1 where it met a descending stream of water4 ,the solution was carried by suitable piping to the point of application4 ,this type was modified in some cases by the substitution of a flow meter of the float type for the inferential pressure meter4 ,a ,this type has recently been withdrawn from the market4 ,illustration3 ,,fig4 #f4--,manual ,control ,chlorinator1 ,solution ,feed1 ,type ,a4 ,another type of apparatus1 developed by ,wallace and ,tiernan1,a is shown in ,figs4 #f and #g4 ,the gas under the pressure indicated by the tank pressure gauge 7,fig4 #f7 passes into the pressure compensating chamber1 which maintains a constant drop in pressure across the chlorine control valve1 through the check valve1 and into the solution jar after measurement in the pulsating meter4 ,the water required for dissolving the chlorine enters the jar through the feed line and check valve and the solution passes along the feed line after being water sealed in a special chamber4 ,the meter is a volumetric displacement one and is regulated by observing the number of pulsations per minute4 ,each pulsation corresponds to #ajj milligrams or #j4jjjbb pound of chlorine2 diagrams for converting pulsations per minute into weight per twenty-four hours are usually provided with the apparatus4 ,this type of meter is suitable for quantities between #j4a and #ab pounds per day and possesses the distinct advantage of enabling the operator to see the actual delivery of the gas4 ,a ,manufactured by ,wallace and ,tiernan ,co4 ,inc4 ,n4 ,y4 ,illustration3 ,,fig4 #g4--,manual ,control ,chlorinator1 ,solution ,feed1 ,type ,b4 ,the quantities of gas exceeding #ab pounds per day the type shown in ,fig4 #g may be used4 ,the gas from the control valve passes through a visible glass orifice which is connected with the manometer4 ,this manometer1 or chlorine meter1 contains carbon tetrachloride and is graduated empirically in terms of weight of chlorine per unit of time4 ,a suitable gauge indicates the back pressure thrown by the check valve and registers the same pressure as the tank gauge when the flow of gas is stopped4 ,the gas passes into the glass cylinder where it is dissolved in water and passes out by the feed pipe4 ,the most accurate range of the orifice type is from #a-f1 i4e4 if the minimum graduation on the scale is #aj1 the maximum is #fj4 ,if quantities less than the minimum graduation are desired1 a smaller orifice with its corresponding scale can be substituted in a few minutes4 ,these types are manually controlled1 but automatic control types1 to meet almost any condition1 can be obtained and are in use in many cities4 ,in some instances 7dry-feed types7 the chlorine gas is not dissolved in water prior to addition to the water requiring treatment but is carried to the point of application as a dry gas and enters the water through a diffusion plate made of carborundum sponge4 ,the sponge becomes saturated with water because of the capillary action of the carborundum upon the water4 ,the pressure of the chlorine in the feed pipe forces the gas through the diffuser in the form of minute bubbles which become saturated with moisture4 ,on meeting the water they immediately go into solution and no gas escapes4 ,the operation of liquid chlorine machines is exceedingly simple4 ,after the cylinders have been connected1 the cylinder valves are opened and the joints tested for leakage by holding a swab of absorbent cotton saturated with strong ammonia under them2 a leakage is indicated by the appearance of white fumes of ammonium chloride4 ,the control valve is then slightly opened and the auxiliary cylinder valves partially opened2 whilst the pressure in the apparatus is slowly increasing the remainder of the joints are tested and if found to be tight1 the cylinder valves are fully opened and the control valve opened to the desired amount4 ,in the solution feed types the water required as solvent is turned on before the control valve is opened4 ,once the apparatus is working1 no further attention is required1 except for the regulation of the dosage in the manual control types1 until the cylinders are replaced4 ,when the stock of gas in the cylinders is almost depleted the pressure falls but it is always preferable to determine the stock by standing the cylinders on a platform scale and weighing at regular intervals4 ,this also provides a check on the apparatus and can be utilised to check the operators4 ,the accumulation of substances that impede the flow of gas is usually slow and is indicated by a gradual increase in the back pressure4 ,the orifice is calibrated at #be pounds back pressure and any deviation from this figure will show a discrepancy between the actual weight of chlorine evaporated and the amount calculated from the scale reading4 ,liquid chlorine is usually sent out by the manufacturers in steel cylinders which contain about #a4a cubic feet of liquid or approximately #ajj pounds 7#a cu4 ft4 #hi4ge pounds74,a ,a ,an effort is now being made to standardise cylinders of #aej lbs4 capacity4 ,for small installations only one cylinder is necessary but it is always preferable to connect more than one4 ,when the flow of gas is rapid the temperature of the liquid chlorine falls and reduces the pressure4 ,the effect of the fall in temperature1 due to the latent heat of evaporation1 can be partially overcome by using a larger number of cylinders2 in addition a source of external heat should be provided that will maintain the temperature of the cylinders at a minimum of #hj deg4 ,f4 ,this is a sine qua non for successful operation4 ,the effect of the temperature upon the pressure in the cylinders is shown in ,diagram ,,vii4 ,illustration3 ,,diagram ,,vii ,,chlorine ,,gas ,,pressures ,,at ,,various ,,temperatures ,in practice it is found impossible to utilise all the gas contained in the containers2 when the cylinders are almost empty the pressure necessary for the operation of the regulating device cannot be obtained and full cylinders must be attached4 ,when sufficient heat is provided the weight of chlorine in the cylinder can be reduced to #a - #a-a_/b pounds before the tank pressure becomes too low4 ,liquid chlorine machines will operate1 with ordinary care1 for long periods4 ,the various parts are made of such metals as experience has demonstrated to be best able to resist the corrosive action of the dry gas and the apparatus is designed to prevent the access of moisture which would otherwise produce corrosion and impede the flow of gas4 ,stoppages are sometimes caused by brown deposits derived from impurities in the liquid chlorine4 ,these are primarily due to variations in the graphite electrodes used in the electrolytic process for the manufacture of chlorine from salt4 ,illustration3 ,,fig4 #h4--;,dunwoodie ,chlorinating ,plant ,treating #djj1jjj1jjj ,gallons ,per ,day for ,new ,york ,city4 ,to convey the dry gas from the apparatus to the point of application1 copper or iron pipes may be used2 for aqueous solutions1 flexible rubber hose must be employed4 ,chlorine water is exceedingly active1 chemically1 and rapidly attacks all the common metals2 ordinary galvanised iron pipe is eroded in a few days and should never be used4 ,liquid chlorine1 for water disinfection1 possesses several marked advantages over the ordinary bleach process4 7#a7 ,the sterilising agent is practically #ajj per cent pure1 the only impurities being traces of carbon dioxide and air1 and does not deteriorate on storage2 it will1 in fact1 keep almost indefinitely4 7#b7 ,liquid chlorine practically eliminates all labour costs because of the simplicity of the apparatus and the concentrated form of the sterilising agent4 ,the apparatus is so compact that all the cylinders and regulating apparatus required for delivering #bjj pounds of gas per day can be placed in an area of about #ej square feet and it can consequently be almost invariably accommodated in locations where the trifling amount of attention required can be obtained without extra cost4 7#c7 ,the sludge problem1 inseparable from bleach installations1 is eliminated4 7#d7 ,regulation of the dosage is simpler and consequently usually more accurate4 ,the dosing apparatus in bleach plants invariably tends to choke and demands regular attention from intelligent operators2 a similar tendency in liquid chlorine machines is easily detected and electrical devices can be installed to indicate automatically any changes in the flow4 7#e7 ,the first cost is smaller4 ,the cost of liquid chlorine machines varies from #djj1 for the small manual control types1 to #a1bjj1 for the automatic control types4 ,the capital outlay is mainly determined by the number of machines and accessories required and not1 within certain limits1 by the capacity4 ,one machine will deliver up to #bjj pounds of gas per day1 an amount sufficient to treat #fj1jjj1jjj ,u4 ,s4 ,a4 gallons 7#ej1jjj1jjj ,imp4 gals47 at #j4dj p4p4m4 of available chlorine4 ,unless duplicate machines are installed for the higher rates1 the first cost is inversely proportional1 though not directly so1 to the volume of water treated4 ,it is in all cases less than the first cost of a bleach plant of equal capacity1 accuracy1 and durability4 7#f7 ,liquid chlorine installations usually tend to produce less complaints as to tastes and odours4 ,this is probably due1 not to any merit of the chlorine per se1 but to a more accurate regulation of the dosage and efficient distribution of the chlorine in the treated water4 ,the advantages ensuing from thorough admixture had only become partially appreciated before liquid chlorine machines were fully developed and they have been more fully utilised in the design of these later installations4 ,claims have also been made that liquid chlorine prevents aftergrowths but no evidence can be adduced in support of this statement4 ,aftergrowths have occurred at many places where this process is employed and in this respect it possesses no advantage over hypochlorite installations4 ,it is also claimed that one pound of liquid chlorine is more efficient1 as a germicide1 than an equal weight of chlorine in the form of bleach4 ,jackson#e has stated that #a pound of chlorine is equal to #i pounds of bleach2 ,kienle 7loc4 cit47 that it was equal to #h pounds of bleach1 whilst ,huy claimed to have obtained an efficiency ratio of #a3aj at ,niagara ,falls1 ,n4 ,y4 ,the conditions of the experiment were not comparable however1 in the last mentioned ratio4 ,catlett1 at ,wilmington1 ,n4 ,c4 7,west#d7 obtained a better bacterial reduction with #a pound of liquid chlorine than with #f pounds of bleach4 ,the efficiency ratio of chlorine to bleach has been reported upon by ,west4#d ,from #aiaj-aiac the mixed filter effluents of the ,torresdale plant at ,philadelphia were treated with bleach but in ,november1 #aiac the liquid chlorine process was substituted4 ,on comparing the results obtained during the same months of the two periods it was found that1 in general1 #a pound of liquid chlorine gave a slightly higher percentage purification than #f-g pounds of bleach4 ,similar results were obtained at the other ,philadelphia plants4 ,the figures published by ,west show that the hypochlorite solutions used were abnormally strong 7#c4f-aj4d per cent of available chlorine71 a condition that would increase the difficulty of extracting all the soluble hypochlorite4 ,it was found indeed1 that1 under the most advantageous conditions1 only #hg per cent of the available chlorine was extracted4 ,the average chlorine content of the bleach used during #aiab-aiac was #cf4a per cent but the figures given would indicate that at least #a4e per cent1 a reduction of #d4f per cent of the total1 was lost during storage4 ,it would seem not improbable that the total loss under average conditions was not less than #bj per cent1 which would reduce the efficiency ratio to #a3d4h-e4f4 ,hale#f also made a comparison of the relative efficiency of liquid chlorine and hypochlorite of lime at ,new ,york1 and the earlier results agreed with ,west's ratio of #a3f-g4 ,an investigation showed that large quantities of chlorine were not extracted from the bleach and when this condition was rectified the total loss averaged only #d per cent and the results obtained were equal to those given by the liquid chlorine machines4 ,hale's comparative figures are given in ,table ,,xxiii4 ,,table ,,xxiii4--,,comparison ,,of ,,liquid ,,chlorine ,,with ,,efficient ,,use ,,of ,,bleach--7,,hale7 ---------------------------------------- ------------------------ ,treatment4 ,water ,number of ,chlorine ,reduction ,treated4 ,samples4 p4p4m4 of ,b4 coli4 ---------------------------------------- ------------------------ ,bleach ,croton #hd #j4bg-j4cf #ic ,liquid chlorine ,bronx #hd #j4bg-j4cf #ic ---------------------------------------- ------------------------ ,hale concluded that1 when efficiently used1 the ratio of chlorine to bleach required to produce equal bacterial purification1 approached #a3c4 ,the results obtained by the author in ,ottawa are similar to those of ,hale4 ,during the earlier period of the bleach treatment a dosage of #a4e p4p4m4 of available chlorine was required to obtain satisfactory purification but various improvements that were subsequently made enabled the quantity to be reduced to #j4h p4p4m4 ,the same raw water usually requires #j4ge to #j4hj p4p4m4 of liquid chlorine to obtain the same purification4 ,the total losses in the ,ottawa bleach plant averaged #f-h per cent and based on these figures the efficiency ratio is approximately #a3c4e4 ,ratios as low as #a3c4e can only be obtained by the supervision of a chemist and this analytical control involves additional expense that must be charged against the bleach process4 ,no chemical analyses are necessary for the control of liquid chlorine plants4 ,disadvantages of ,liquid ,chlorine ,plants4 ,the main objection to the use of liquid chlorine is that the slight leaks of gas occur occasionally and unless removed by forced ventilation may produce a concentration of chlorine that will injure the operators4 ,pettenkofer and ,lehmann#g found that #j4jja-j4jje per cent of chlorine in air affected the respiratory organs2 #j4jd-j4jf per cent produced dangerous symptoms1 whilst concentrations exceeding #j4jf per cent rapidly proved fatal4 ,the danger of gas leakages can be eliminated by placing the apparatus in a small separate room provided with a fan and a ventilation duct4 ,by the liberal use of glass in the construction of the room1 the operation of the plant can be seen at all times without entering the chamber4 ,a portion of the liquid chlorine apparatus is made of glass and is consequently easily fractured4 ,duplicates of the glass parts should be kept in stock to prevent interrupting the supply of gas2 a duplicate machine is also advisable in large installations4 ,cost of ,treatment4 ,prior to the outbreak of war in #aiad1 liquid chlorine sold at #aj-aa cents per pound in small quantities and for #h-i cents per pound in large shipments4 ,in #aiag the price was #ah-bj cents per pound for small quantities and #ae cents upwards for large contracts4 ,canadian prices are #be per cent higher4 ,the amount of chlorine required for satisfactory disinfection 7see ,chapter ,,iii7 depends upon the nature of the water and the cost of treatment varies accordingly4 ,in the majority of plants the cost varies from #be-ij cents per million gallons4 ,popularity of ,process4 ,since #aiac1 when the first commercial liquid chlorine machines were used1 the popularity of this process has increased in a most remarkable manner4 ,in #aiac over #a1gjj million gallons per day were treated with hypochlorite2 in #aiae1 #a1jjj million gallons per day were treated with liquid chlorine and an approximately equal amount with hypochlorite2 in ,january #aiah1 the amounts were #c1ejj million gallons per day 7liquid chlorine7 and #ejj million gallons per day 7hypochlorite74 ,this wonderful development has been largely due to the intrinsic merits of the process and the reliability of the machines manufactured although it has been indirectly assisted by the excessive cost of hypochlorite during #aiae-aiaf4 ,liquid chlorine machines are being used for the purification of water on the ,western ,front of the ,european battlefield4 ,the outfit is a mobile one and consists of a rapid sand filter1 liquid chlorine apparatus1 a small storage tank and solution tanks4 ,owing to the limited contact period available a large dosage of chlorine is employed and the excess afterwards removed by the addition of a solution of sodium thiosulphate4 ,chlorine ,water4 ,marshall#h has proposed the use of chlorine water for the sterilisation of water for troops4 ,the solution is contained in ampoules which are of two sizes1 one for water carts and the other for water bottles of one quart capacity4 ,the coefficient of solubility of chlorine1 from #aj deg4-#da deg4 ,c4 is ,c #c4jcfa - #j4jdaift #j4jjjaajgt#b2 when t #aj deg4 ,c4 #a c4cm4 of water absorbs #b4eh c4cms4 of chlorine or #h4b m4gr41 a quantity sufficient to give a concentration of #a p4p4m4 in #h litres of water4 ,marshall has stated that1 when pure materials are used1 chlorine water is stable but the author is unable to confirm this4 ,a saturated solution of chlorine in distilled water lost over #ej per cent of its available chlorine content when stored for five days in the dark at #gj deg4 ,f4 ,the chlorine present as hypochlorous acid increased slightly but the quantity never exceeded very small proportions4 ,chlorine solutions decompose in accordance with the equation1 ,cl#b ,h#b,o #b;,h,cl ,o4 ,although chlorine water appears to be of little value because of its instability there appears to be no reason why chlorine hydrate should not be successfully employed4 ,the hydrate was first prepared by ,faraday#i by passing chlorine into water surrounded by a freezing mixture4 ,a thick yellow magma resulted from which the crystals of chlorine hydrate were separated by pressing between filter paper at #j deg4 ,c4 ,the hydrate prepared by ,faraday was found to have the composition represented by the formula ,cl4#e;,h#b,o but later investigators have shown that more concentrated hydrates can be prepared4 ,roozeboom#aj prepared a hydrate represented by the formula ,cl4#d;,h#b,o and ,forcrand#aa one containing only #c-a_/b molecules of water 7,cl#b4g;,h#b,o74 ,chlorine hydrate separates into chlorine gas and chlorine water at #i4f deg4 ,c4 in open vessels and at #bh4g deg4 ,c4 in closed vessels4 ,pedler#ab has shown that when the ratio of ,cl#b3;,h#b,o is #a3fd or greater1 the mixture of chlorine hydrate and water exhibits great stability and can be exposed to tropical sunlight for several months without decomposition4 ,cl#b4fd;,h#b,o contains #e4h per cent of chlorine and about #h4 c4cms4 would be required to give a concentration of #a p4p4m4 in #aaj ,imp4 gallons of water1 the usual capacity of a military water cart4 ,,bibliography #a ,nesfield4 ,public ,health1 #aijc1 #ae1 #fja4 #b ,darnall4 ,j4 ,amer4 ,pub4 ,health ,assoc41 #aiaa1 #a1 #gac4 #c ,kienle4 ,proc4 ,amer4 ,waterworks ,assoc41 #aiac1 #bgd4 #d ,west4 ,j4 ,amer4 ,waterworks ,assoc41 #aiad1 #a1 #djj-ddf4 #e ,jackson4 ,proc4 ,amer4 ,waterworks ,assoc41 #aiac4 #f ,hale4 ,proc4 ,n4 ,j4 ,san4 ,assoc41 #aiad4 #g ,pettenkofer and ,lehmann4 ,munich ,acad41 #ahhg4 #h ,marshall4 ,conv4 ,amer4 ,elect4 ,chem4 ,soc41 #aiag4 ,eng4 and ,contr41 #aiah1 #di1 #dj4 #i ,faraday4 ,q4 ,j4 ,s41 #ae1 #ga4 #aj ,roozeboom4 ,rec4 ,trav4 ,chim41 #ahhe1 #c1 #ei4 #aa ,forcrand4 ,comp4 rend41 #aijb1 #acd1 #iia4 #ab ,pedler4 ,j4 ,c4 ,s41 #ahij1 #hc1 #fac4 ,,chapter ,,viii ,,electrolytic ,,hypochlorites ,,and ,,chlorine ,since #ahhi when ,webster first proposed the use of electrolysed sea-water as a disinfectant1 various attempts have been made to introduce electrolytic hypochlorites for the bactericidal treatment of water and sewage4 ,two of these preparations were named ,hermite fluid1 and electrozone 7c4f4 page #e74 ,sodium hypochlorite1 made by passing chlorine into solutions of caustic soda1 or by the decomposition of bleach by sodium carbonate1 has also been used and preparations of this character have been sold under such names as ,eau de ,javelle1 ,labarraque solution1 chloros1 and chlorozone4 ,these solutions contain mixtures of sodium hypochlorite and sodium chloride together with some free alkali4 ,chlorozone was the name given by ,count ,dienheim-,brochoki to a number of preparations patented in #ahgf and subsequently down to #ahhe4 ,they were produced by passing air and chlorine into solutions of caustic soda4 ,lunge and ,landolt#a have shown that the air introduced is without effect and that the advantages claimed for chlorozone are illusory4 ,the earliest electrolytic installation on this continent was operated at ,brewster1 ,n4 ,y41 in #ahic and since that date several plants have been erected where local conditions conduced to economical operation4 ,when a uni-directional current of electricity is passed through a solution of sodium chloride1 the salt is dissociated and the components liberated1 ,na,cl ,na ,cl4 ,if the elements are not separated1 the chlorine combines with the sodium hydrate1 formed by the action of the sodium on the water1 to form sodium hypochlorite4 ,the equations #b,na #b;,h#b,o #b,na,o,h ,h#b1 and #b,na,o,h ,cl#b ,na,o,cl ,na,cl ,h#b,o show that only one-half of the chlorine produced is found as hypochlorite2 the other half reforming sodium chloride4 ,several types of electrolysers have been used for the production of hypochlorites and chlorine but only two are suitable for water-works purposes3 in one1 the cathodic and anodic products recombine in the main body of the electrolyte2 in the other1 the diaphragm process1 they are separated as removed and the final products are chlorine gas and a solution containing caustic soda and some undecomposed salt4 ,until a few years ago the non-diaphragm process was the only one used for water treatment and it will consequently be discussed first4 ,non-diaphragm ,process4 ,the theoretical voltage required for the decomposition of sodium chloride is #b4c but when the products recombine in the electrolyte1 side reactions occur which increase the minimum voltage to #c4ed4 ,on this basis one kilowatt hour gives #bgb ampere hours and as one ampere hour is theoretically capable of producing #a4cc grams of chlorine1 #a4ba kilowatt hours are necessary for the production of #a pound of chlorine by the decomposition of #a4fe pounds of salt4 ,charles ,watt 7#ahea7 discovered this process and was the first to recognize the necessary conditions which are 7#a7 insoluble electrodes1 7#b7 low temperature of electrolyte1 and 7#c7 rapid circulation of electrolyte from the cathode to the anode4 ,the control of the temperature is very important1 for as it increases1 side reactions occur with the formation of chlorates1 and the efficiency is decreased4 ,the non-diaphragm cells used in ,europe 7,haas and ,oettel1 ,kellner1 ,hermite1 ,vogelsand1 and ,mather and ,platt7 have been described by ,kershaw4#b ,in the ,haas and ,oettel electrolyser the electrodes are composed of carbon but in the other types at least one electrode is made from platinum or a platinum alloy4 ,the ,dayton electrolyser1 which is the cell most familiar in ,north ,america1 is shown in ,fig4 #i4 ,illustration3 ,,fig4 #i4--;,dayton ,electrolytic ,cell4 ,the outer cell is made of soapstone and is approximately #b-a_/b feet long and #b feet wide4 ,the main electrodes consist of four pieces of ,atcheson graphite connected together by screws and metal strips to which is attached a clamp for connecting electrical terminals4 ,circulation of the brine is produced by glass baffle plates and secondary electrodes placed one inch apart between the main electrodes4 ,the cell is intended to be used at #aaj-volts pressure but by wiring two cells in series a #bbj-volt circuit may be employed4 ,an inlet and outlet are provided at each end of the tank to permit the direction of the flow to be periodically reversed for the purpose of removing the lime deposit from the graphite plates4 ,the salt solution is prepared in wooden tanks from coarse clean salt 7ground rock salt is unsuitable71 containing as little iron as possible1 in the proportion of #ej pounds to #ajj gallons of water4 ,after passing through a gravel or other suitable filter the brine solution is carried by brass pipes to the electrolyser4 ,the rate of flow is adjusted to the temperature of the hypochlorite solution leaving the cell but under normal conditions it is stated that the cell described will pass #dj gallons per hour with a consumption of #gj amperes and produce #b-a_/b pounds of chlorine per hour4 ,this is equal to #h pounds of salt and #c4jh kilowatt hours per pound of chlorine4 ,after the cells have been operated for several months the efficiency usually falls and #aj-aa pounds of salt and #c4e-c4g kilowatt hours are required for the production of one pound of chlorine4 ,the concentration of the hypochlorite solution is usually about #f grams per litre4 ,rickard#c stated that by cooling the ,dayton cell with ice #a pound of chlorine could be produced from #b4fe kilowatt hours and #f4i pounds of sodium chloride2 without cooling the figures were #c4fb kilowatt hours and #g4b pounds of salt4 ,based on the figures that have been obtained from mature cells1 the efficiency of the ,dayton cell as compared with those described by ,kershaw is as follows3 ---------------------------------------- ---------------------- ,,salt4 ,,power4 ,,per ,,pound ,,of ,,available ,,chlorine4 ,type of ,cell4 ---------------------------------------- -- ,pounds4 ,per ,cent ,kilowatt ,efficiency ,consumed4 ,hours4 ,per ,cent4 ---------------------------------------- -------------------- ,haas and ,oettel #aj4g #ae4d #c4h #ca4i ,kellner #g4e #bb4j #b4ge #dc4i ,hermite #aa4b #ad4e #b4hg #db4b ,mather and ,platt 4444 4444 #b4ge #dc4i ,dayton #aj4j #af4e #c4f #cc4f ,theoretical #a4fe #ajj4j #a4ba #ajj4j ---------------------------------------- -------------------- ,the cost of production depends upon local conditions3 if alternating current is available at #cj per horse-power per annum1 and low-grade salt can be obtained for #e per ton the cost of #a pound of chlorine would be ---------------------------------------- ----- ,,cost 7,,cents7 ,,per ,,pound ,,of ,,available ,,chlorine4 ,type of ,cell4 -------------------------- ,salt4 ,current4 ,total4 ---------------------------------------- --- ,haas and ,oettel #b4fg #a4ig #d4fd ,kellner #a4hg #a4dc #c4cj ,hermite #b4hj #a4di #d4bi ,dayton #b4ej #a4ib #d4db ---------------------------------------- --- ,the electrical and chemical efficiencies of the ,haas and ,oettel and ,dayton cells1 which contain carbon electrodes1 are smaller than those containing platinum electrodes but for water sterilisation the carbon cells have been found to be more suitable4 ,to prevent the action of magnesium salts on the platinum electrodes it is necessary to use a higher grade of salt or to provide means of purification4 ,because of the absence of a base and the presence of chlorides1 electrolytic hypochlorite cannot be stored for more than a few hours without appreciable loss of titre4 ,unless used for the treatment of the effluent of a filter plant operated at a fairly constant rate a small storage tank is necessary to compensate for the irregular demand and to provide the head required by orifice feed boxes4 ,small variations can be made by regulating the flow through the cells but large ones are not compatible with efficiency1 which is the highest under a constant load4 ,claims have been made that electrolytic hypochlorite is more efficient as a germicide than bleach when compared on the basis of their available chlorine content but no evidence of it has been produced4 ,bleach contains an excess of base1 which retards the germicidal action1 and electrolytic hypochlorite contains an excess of sodium chloride1 which accelerates it 7,race#d7 but the ultimate effect is the same with both4 ,this is shown in ,table ,,xxiv4 ,,table ,,xxiv4,a--,,comparison ,,of ,,bleach ,,with ,,electrolytic ,,hypochlorite ---------------------------------------- -------------- ,,bleach4 ,,electrolytic ,,hypochlorite4 -------------------------------------- ,contact ,period4 ,available ,chlorine4 ,parts ,per ,million4 ------------------------------------ #j4d #j4f #j4d #j4f ---------------------------------------- ------------ ,nil #ahb 444 444 444 #aj minutes #acj #aj #abj #h #a hour #ff #a #fj #j #b hours #c #j #a #j #c-a_/b hours #j #j #j #j ---------------------------------------- ------------ ,a ,results are ,b4 coli per #aj c4cms4 ,electrolytic hypochlorite has a greater germicidal velocity than bleach but the difference is so small as to be of no practical importance4 ,rabs#e experimented with various hypochlorites but was unable to find any appreciable differences in their germicidal action4 ,if electrical power can be obtained at a very low cost1 or if the cost is merely nominal1 as it is when there is an appreciable difference between the normal consumption and the peak load upon which the rate is based1 the electrolytic hypochlorite method offers some advantages but in the great majority of plants it cannot economically compete with bleach4 ,the instability of the liquor and cell troubles have also prevented the process being generally utilised4 ,baltimore and ,cincinnati experimented with this method but did not adopt it4 ,winslow#f has reported that1 owing to the difficulty in obtaining bleach since the outbreak of war1 ,petrograd has used electrolytic hypochlorite made from salt4 ,diaphragm ,process4 ,the various types of diaphragm cells that have been commercially operated are of two varieties3 7#a7 cells with submerged diaphragms and 7#b7 cells in which the electrolyte comes in contact with one face only of an unsubmerged diaphragm4 ,the ,le ,sueur1 ,gibbs1 ,crocker1 ,billiter-,siemens1 ,nelson1 and ,hargreaves-,bird cells are of the submerged diaphragm variety4 ,the ,nelson cell has been operated for some time at the filtration plant at ,little ,falls1 ,n4 ,j4 ,the cells are fed with brine solution previously purified by the addition of soda ash and have given fairly successful results although the cost of maintenance is comparatively high4 ,tolman#g has reported that several towns in ,west ,virginia use a bleach solution prepared by absorbing chlorine1 manufactured by the ,hargreaves-,bird process1 in lime water2 the solution contains about #a4ie per cent of available chlorine4 ,the diaphragms in both the submerged and unsubmerged types are usually constructed either with asbestos paper or cloth1 placed in such a manner as to divide the cells into two separate compartments3 the anodic1 into which the brine is fed and where the chlorine is produced2 and the cathodic1 where caustic soda is formed4 ,by maintaining the liquor in the anodic compartment at a higher elevation than in the cathodic one1 the direction of flow is towards the latter1 but owing to osmosis and diffusion the separation is not complete and a portion of the caustic soda passes the diaphragm and produces hypochlorite with a consequent loss of efficiency and rapid deterioration of the anodes4 ,with the exception of the ,billiter-,siemens cell1 the submerged diaphragm cells operate at not more than #he per cent efficiency and the cost of maintenance is usually high4 ,in the non-submerged diaphragm types the invasion of the anodic compartment by caustic is much reduced and the efficiency and life increased4 ,an electrolyser of the non-submerged diaphragm type is the ,allen-,moore cell which has been adopted by the ,montreal ,water and ,power ,co4 ,this has been described by ,pitcher and ,meadows4#h ,the general lay-out of the installation is shown in ,fig4 #aj1 and the essential features are3 a salt storage bin having a capacity of #dj tons2 the brine saturating and purifying apparatus2 duplicate #ae horse-power motor-generator sets2 four chlorine cells2 and the silver ejectors and distributing lines for carrying the chlorine solution to the point of application4 ,illustration3 ,,fig4 #aj--;,brine ,saturating and ,purifying ,equipment4 ,the brine solution1 which is prepared by passing water through the saturators previously filled with salt1 is delivered to the two concrete reaction tanks where an amount of soda ash and caustic liquor sufficient to combine with the calcium and magnesium salts is added1 and the mixture filtered through sand and stored in the purified brine tanks4 ,to prevent the formation of hypochlorites by the interaction of chlorine and alkali1 the alkalinity of the liquor is determined and sufficient hydrochloric acid added to ensure an acidity of #j4ja per cent4 ,the acid brine is delivered at one end of the four cells 7,fig4 #aa7 each of which is #g feet long and #bj-c_/h inches wide and consumes #fjj amperes at #c4c volts4 ,the cell box is built of concrete and is provided with a perforated wrought iron cathode box and graphite anode plates which are separated by an unsubmerged asbestos paper diaphragm4 ,illustration3 ,,fig4 #aa4--,sections of ,allen-,moore ,cell4 ,each cell has a capacity of #cb pounds of chlorine per day and the gas flow is determined by measuring the volume of caustic soda produced in a given period of time and calculating the weight from the volume and concentration as determined by titration with standard acid2 each gram of ,na,o,h is equal to #j4hh gram of chlorine4 ,the efficiency of the cell is obtained by dividing the number of grams of chlorine produced per hour by the product of the current volume 7in amperes7 and the factor #a4cc1 the theoretical production of chlorine for one ampere hour4 ,the average efficiency of the ,montreal cells was found to be #ic per cent4 ,the installation comprises four cells1 one being held in reserve1 and the annual cost of producing #ij pounds of chlorine per day is given as #b1ejj4 ,the details are3 ,salt at #h4jj per ton1 delivered #ejj4jj ,power1 #ae ,h4,p41 at #cj4jj flat rate #dej4jj ,labour and superintendence #ejj4jj ,interest at #f per cent on capital cost #cjj4jj ,depreciation1 #ae per cent #gej4jj --------- #b1ejj4jj cost per pound of chlorine #g4f cents4 ,the diaphragm cells1 like the non-diaphragm ones1 operate most efficiently under a constant load2 they are consequently suitable for treating the effluent of filter plants4 ,where very cheap electrical power can be obtained1 the cost per pound of available chlorine is less for the electrolytic method just described than for liquid chlorine or chlorine obtained from bleach2 but this condition obtains in very few places4 ,mr4 ,j4 ,a4 ,meadows has suggested to the author that the cost could be reduced by converting the chlorine gas into hypochlorite and then adding dilute ammonia as in the chloramine process 7vide page #aae74 ,the caustic liquor1 usually run to waste from the cathodic compartment1 could be delivered into a feed box from which it would be drawn off by the water injector used for dissolving the chlorine gas4 ,,bibliography #a ,lunge and ,landolt4 ,jour4 ,soc4 ,dyers and ,colourists1 ,nov4 #be1 #ahhe4 #b ,kershaw4 ,jour4 ,soc4 ,chem4 ,ind41 #aiab1 #ca1 #ed4 #c ,rickard4 ,quar4 ,bull4 ,ohio ,board of ,health1 ,oct4-,dec41 #aijd4 #d ,race4 ,jour4 ,amer4 ,waterworks ,assoc41 #aiah1 #e1 #fc4 #e ,rabs4 ,hygienische ,rundschau1 #aija1 #aa4 #f ,winslow4 ,public ,health ,rpts4 ,u4 ,s4 ,p4 ,h4 ,s41 #aiag1 #cb1 #bbjb4 #g ,tolman4 ,jour4 ,amer4 ,waterworks ,assoc41 #aiag1 #d1 #ccg4 #h ,pitcher and ,meadows4 ,jour4 ,amer4 ,waterworks ,assoc41 #aiag1 #d1 #ccg4 ,,chapter ,,ix ,,chloramine ,chloramine 7,,nh#b;,cl71 a chemical compound in which one of the hydrogen atoms of ammonia has been replaced by chlorine1 was discovered by ,raschig#a in #aijg4 ,chloramine was prepared by cooling dilute solutions of bleach and ammonia and adding the latter to the former contained in a flask surrounded by a freezing mixture4 ,the proportions were as the equivalent weights of anhydrous ammonia and available chlorine 7approximately two parts by weight of chlorine to one part by weight of ammonia74 ,after gas evolution had ceased the mixture was saturated with zinc chloride and the magma distilled under reduced pressure4 ,the distillate was a dilute solution of comparatively pure chloramine4 ,the first to notice the effect of ammonia on the germicidal value of hypochlorites was ,s4 ,rideal#b who noted that during the chlorination of sewage1 the first rapid consumption of chlorine was succeeded by a slower action which continued for days in some instances1 and was accompanied by a germicidal action after free chlorine or hypochlorite had disappeared4 ,rideal stated that3 ,it became evident that chlorine1 in supplement to its oxidising action1 which had been exhausted1 was acting by substitution for hydrogen in ammonia and organic compounds1 yielding products more or less germicidal4 ,on investigating the effect of ammonia on hypochlorite it was found that the addition of an equivalent of ammonia to electrolytic hypochlorite increased the carbolic acid coefficient of #b4ah1 for one per cent available chlorine1 to #f4cf 7nearly three times the value74 ,further experimental work showed that the increase was due to the formation of chloramine4 ,the author1 in #aiae1 during a series of experiments on the relative germicidal action of hypochlorites1 attempted to prepare the ammonium salt by double decomposition of bleach and ammonium oxalate solutions4 ,ca7,o,cl7#b 7,,nh#d7b;,c#b,o#d ,ca,c#b,o#d #b,,nh#d,o,cl4 ,the velocity of the germicidal action of the solution was found to be about ten times greater than the germicidal velocities of other hypochlorites of equal concentrations1 7,race#c71 and from a consideration of the chemical formula of ammonium hypochlorite it appeared probable that it would be very unstable and decompose into chloramine1 which ,rideal had previously shown to have an abnormal germicidal action1 and water4 ,,nh#d,o,cl ,,nh#b;,,cl ,h#b,o4 ,after these results have been confirmed1 the effect of adding ammonia to bleach solution was tried and it was found that #j4bj p4p4m4 of available chlorine and #j4aj p4p4m4 of ammonia produced equally good results as #j4fj p4p4m4 of chlorine only4 ,similar results were obtained on the addition of ammonia to electrolytic hypochlorite4 ,experiments made with a view to determining the most efficient ratios of ammonia gave very surprising results3 chlorine to ammonia ratios 7by weight7 between #h3a and #a3b gave approximately the same germicidal velocity4#c ,the action of the ammonia on the oxidising power of bleach1 as measured by the indigo test1 was also found to be disproportionate to the amount added4 ,the oxidising action of various mixtures of bleach and ammonia as measured by the rate of absorption of the available by the organic matter in the ,ottawa ,river water is shown in ,table ,,xxv4 ,,table ,,xxv4--,,rate ,,of ,,absorption ,,of ,,available ,,chlorine ---------------------------------------- --------------------- ,ratio ,chlorine _/ ,ammonia ,,percentage ,,of ,,original ,,found ,,after by ,weight4 --------------------------------- #aj ,mins4 #d ,hours4 #bj ,hours4 ---------------------------------------- ------------------- ,infinity 7ammonia absent7 #ff4h #dj4j #be4a #h3a #hc4b #gg4h #fg4c #d3a #ig4b #id4g #hh4e #b4g3a #ih4c #if4e #ib4h #b3a #ii4h #ih4b #if4b ---------------------------------------- ------------------- ,the #h3a ratio caused a marked reduction in the rate of absorption of the chlorine whilst a #d3a ratio was almost as active as the ratios containing more ammonia4 ,at the time when the abnormal results were obtained with ammonium hypochlorite and mixtures of bleach and ammonia1 the phenomenon appeared to be of scientific interest only and especially so as ,rideal had attributed the obnoxious tastes and odours1 sometimes produced by chlorination1 to the formation of chloramines4 ,during the winter of #aiae-aiaf the price of bleach1 however1 advanced to extraordinary heights and the author then determined to try out the process on a practical scale for the purification of water4 ,a subsidiary plant pumping about #bjj1jjj ,imperial gallons per day 7#bdj1jjj ,u4 ,s4 ,a4 gallons7 was found to be available for this purpose and the chloramine process was substituted for the bleach method previously in operation4 ,the process was commenced by the addition of pure ammonia fort1 in the amount required to give a chlorine to ammonia ratio of #b3a1 to the bleach solutions in the barrels4 ,the results were not in accordance with those obtained in the laboratory and it was found that the samples of bleach solutions received for analysis were far below the strength calculated from the amount of dry bleach used4 ,this experience was repeated on subsequent days and the deficiency was found to increase on increasing the ammonia dosage4 ,solutions of similar concentration were then used in the laboratory with similar losses1 and it was observed that on the addition of ammonia a copious evolution of gas occurred4 ,an investigation showed that the ammonia and bleach must be mixed as dilute solutions and prolonged contact avoided 7vide p4 #abg74 ,alterations were accordingly made in the plant and the bleach and ammonia were prepared as dilute solutions in separate vessels and allowed to mix for only a few seconds before delivery to the suction of the pumps4 ,this method of application was instantaneously successful and results equal to those obtained in the laboratory were at once secured4 ,the dosage was reduced until the bacteriological results were adversely affected and continued at values slightly in excess of this figure 7#j4ae p4p4m47 for a short period to prove that the process was reliable4 ,from a consideration of the work of ,raschig and ,rideal1 it appeared that the most efficient proportions of available chlorine and ammonia would be two parts by weight of the former to one part of the latter and this ratio was maintained during the run on the experimental plant4 ,lower ratios of chlorine to ammonia were contra-indicated by the laboratory experiments1 which showed that the efficiency was not increased thereby whilst higher ratios were left for future consideration4 ,the results obtained on the experimental plant1 together with those obtained on the main plant1 where #bd million gallons per day were treated with bleach only1 are given in ,tables ,,xxvi1 ,,xxvii and ,,xxviii4 ,the two periods given represent the spring flood condition and that immediately preceding it2 these are respectively the worst and best water periods4 ,the results in both cases are from samples examined approximately two hours after the application of the chemicals4 ,the cost data were calculated on the current ,new ,york prices of bleach and ammonia4 ,,table ,,xxvi4--,,comparison ,,of ,,hypochlorite ,,and ,,chloramine ,,treatment ,,bacteriological ,,results ---------------------------------------- --------------------------------- ,,raw ,,water4 ,,treated ,,with ,,hypo- ,,treated ,,with ,,hypochlorite ,,chlorite ,,alone4 ,,and ,,ammonia4 ---------------------------------------- ---------------------- #aiaf ,bacteria ,bacteria ,bacteria per cubic per cubic per cubic centimeter4 ,b4 centimeter4 ,b4 centimeter4 ,b4 -----------coli----------coli ------------coli ,agar ,agar ,index,agar ,agar ,index 7#a7;,agar ,agar ,index 7#a7 7#b7 #a #c per #a #c per #a #c per day days #ajj day days #ajj day days #ajj at at cc4 at at cc4 at at cc4 #cg deg4 #bj deg4 #cg deg4 #bj deg4 #cg deg4 #bj deg4 ,c4 ,c4 ,c4 ,c4 ,c4 ,c4 ---------------------------------------- ------------------------ ,mar4 #dd #bch #ce4g #d #ab #j4adj4ij #d #ab #j4ad #j4bbj4aa #ae-ca ,april#c1jiiad1djhaie4e #cb #ef #j4eja4aj #cc #bdf #j4gd #j4bej4ac #a-ai ---------------------------------------- ------------------------ ,legend3 7#a7 ,available chlorine parts per million4 7#b7 ,ammonia1 parts per million4 ,,table ,,xxvii ,percentage ,reduction ---------------------------------------- -------------------------------- ,,hypochlorite ,,alone4 ,,hypochlorite ,,and ,,ammonia4 ---------------------------------------- --------------------- ,bacteria ,available ,bacteria ,available per cubic ,b4 chlorine per cubic ,b4 ,chlorine centimeter4 coli parts centimeter4 coli ,parts -------------- ,index per ------------- ,index per ,agar ,agar per #ajjmillion4 ,agar ,agar per #ajj,million4 #a ,day #c ,days cubic #a ,day #c ,days cubic at at centi- at at centi- #cg deg4 ,c4 #bj deg4 ,c4 meters4 #cg deg4 ,c4 #bj deg4 ,c4meters4 ---------------------------------------- -------------------------- ,mar4 #ij4i #ie4h #ii4i #j4ij #ij4j #ie4j #ii4g #j4bb #ae-ca ,april #ih4i #ii4f #ii4g #a4aj #ih4c #ih4i #ii4f #j4be #a-ai ---------------------------------------- -------------------------- ,,table ,,xxviii ,cost ,per ,million ,imperial ,gallons,a --------------------------------------- ,hypochlorite ,hypochlorite alone4 and ammonia4 --------------------------------------- ,mar4 #ae-ca #a4ab #j4df ,april #a4bf #j4ed --------------------------------------- ,a ,calculated as ,bleach at #c4hj per #ajj pounds and aqua ammonia 7#bf deg4 ,be47 at #e-a_/b cents per pound4 ,the results were so satisfactory that the author recommended the adoption of the process on the main chlorinating plant but owing to conditions imposed by the ,provincial ,board of ,health the process was not operated until ,february1 #aiag4 ,in place of ammonia fort1 aqua ammonia 7#bf deg4 ,be471 containing approximately #bi per cent of anhydrous ammonia1 was used4 ,the material was first examined by the presence of such noxious substance as cyanides and found to be very satisfactory4 ,illustration3 ,,fig4 #ab4--,sketch of ,ottawa ,chloramine ,plant4 ,the general design of the plant is shown in ,fig4 #ab4 ,the bleach is mixed in tank ,a as a solution containing #j4c to #j4f per cent of available chlorine and delivered to tanks ,b and ,d1 each of which has a twenty-four-hour storage capacity4 ,the ammonia solution is mixed and stored in tank ,b and contains #j4c-j4e per cent of anhydrous ammonia4 ,the two solutions are run off into boxes ,e and ,f which maintain a constant head on valves ,v and ,v' controlling the head on the orifices4 ,both orifices discharge into a common feed box ,g from which the mixture is carried by the water injector ,j through one of duplicate feed pipes and discharged into the suction well through a perforated pipe4 ,as tank ,b was previously used as a bleach storage tank1 the change from hypochlorite alone to chloramine necessitated very little expense4 ,the treatment was commenced by gradually increasing the quantity of ammonia1 until a dosage of #j4ab p4p4m4 was reached1 and constantly increasing the dosage of bleach1 which was formerly #j4ic p4p4m4 of available chlorine4 ,owing to the restrictions imposed by the ,provincial authorities it has not been possible to maintain a dosage as low as that indicated as sufficient by the experimental plants results1 but some interesting data have been obtained4 ,table ,,xxix shows the results obtained from ,february to ,october1 #aiag1 from the chloramine treatment at ,ottawa and also those obtained with liquid chlorine at ,hull where the same raw water is treated with #j4g-j4h p4p4m4 of chlorine4 ,,table ,,xxix4--,,chloramine ,,results ,,at ,,ottawa ---------------------------------------- -------------------------- ,b4 coli ,hull ,,per #ajj ,c4,,cms4 ,,dosage ,p4,p4,m4 ,b4 coli #aiag -------------,turbidity4 ,colour4-----------------,per #ajj ,raw ,tap c4cms4 ,water4 ,water4 ,chlorine4,ammonia4 ---------------------------------------- ------------------------ ,feb4 #bfh #j4hh #c #dj #j4eg #j4je 4444 ,mar4 #a-ah #bej #j4if #d #dj #j4cb #j4aa 4444 ,mar4 #a-ca #fdc #j4dc #d #dj #j4dg #j4ad 4444 ,april #ebbh #j4cd #ca #cb #j4ef #j4aj 4444 ,may #afb #j4jh #c #ci #j4eb #j4jh 4444 ,june #aad #j4jh #c #da #j4ea #j4jh 4444 ,july #bcg #j4jh #e #da #j4ea #j4jh #dd4d ,aug4 #afe #j4jh #d #db #j4ea #j4aj #bh4j ,sept4 #ee #j4jh #f #db #j4ej #j4ji #ae4b ,oct4 #ca #j4ae #e #db #j4db #j4jh #a4a ---------------------------------------- ----------------- ,average #baa #j4bb #g #dj #j4ea #j4ji ---------------------------------------- ------------------------ ,at the height of the spring floods the raw water contained #hj p4p4m4 of turbidity and over #ejj ,b4 coli per c4cm4 but #j4f p4p4m4 of chlorine and #j4ac p4p4m4 of ammonia reduced the ,b4 coli index in the tap samples to #b4e per #ajj c4cms42 samples taken in ,hull on the same day 7treated with #j4g-j4h p4p4m4 of liquid chlorine7 gave a ,b4 coli index of #bf4g4 ,previous experiences in ,ottawa has shown that a dosage of approximately #a4e p4p4m4 of available chlorine is required to reduce the ,b4 coli index to #b4j per #ajj c4cms4 under similar physical and bacteriological conditions4 ,during the period of nine months covered by the results in ,table ,,xxix1 only five cases of typhoid fever were reported in which the evidence did not clearly indicate that the infection had occurred outside the city4 ,the reduction in the bleach consumed during the same period effected a saving of #c1bjj4 ,during one period of operation the hypochlorite dosage was gradually reduced to ascertain what factor of safety was maintained with a dosage of #j4e p4p4m4 of available chlorine and #j4jf-j4jh p4p4m4 of ammonia4 ,the results are shown in ,diagram ,,viii4 ,the percentage of samples of treated water showing ,b4 coli in #ej c4cms4 was calculated from the results of the examination of #d-g samples daily4 ,the results showed that it was possible to reduce the chlorine dosage to #j4be p4p4m4 with #j4jf p4p4m4 of ammonia without adversely affecting the bacteriological purity of the tap supply and fully confirmed the experimental results previously obtained4 ,the lowest ratio of available chlorine to ammonia used during this test was approximately #d3a4 ,this is the ratio indicated by a consideration of the theory of the reaction1 and not #b3a as was formerly stated 7,race#d74 ,if bleach is represented as ,ca7,o,cl7#b1 the equation ,ca7,o,cl7#b #b,,nh#c #b,,nh#b;,cl ,ca7,,oh7#b would indicate a ratio of #b3a2 but only one molecule of ,ca7,o,cl7#b is produced from two molecules of bleach and the theoretical ratio is therefore #d3a 7#adb3cd71 #b;,ca,o,cl#b ,ca,cl#b ,ca7,o,cl7#b and ,ca7,o,cl7#b #b,,nh#c ,cl #adb #cd #b,,nh#b;,cl ,ca7,,oh7#b4 ,the chlorine to ammonia ratio is very important because of its influence on the economics of the process 7vide p4 #abd74 ,illustration3 ,,diagram ,,viii ,,chloramine ,,treatment1 ,,ottawa ,all the laboratory and works results that have been obtained in ,ottawa indicate the importance of an adequate contact period4 ,the superiority of chloramine over other processes is due to the non-absorption of the germicidal agent and to obtain the same degree of efficiency the contact period must be increased as the concentration is decreased4 ,for this reason the best results will be obtained by chlorinating at the entrance to reservoirs or under other conditions that will ensure several hours contact4 ,at ,ottawa the capacity of the pipes connecting the pumping station 7point of chlorination7 and the distribution mains provides a contact period of one and a quarter hours but even better results would be obtained if the contact period were increased4 ,the general results obtained during the use of chloramine at ,ottawa in #aiag have shown that the aftergrowths noted during the use of hypochlorite 7see p4 #ef7 have been entirely eliminated and that the ,b4 coli content of the tap samples from outlying districts has been invariably less than that of samples taken from taps near to the point of application of the chloramine4 ,at ,denver1 ,col41 where the chloramine process has also been used1 similar results were obtained#e3 four days after the initiation of the chloramine treatment the aftergrowth count on gelatine of the ,capitol ,hill reservoir dropped from #ae1jjj to #aj per c4cm4 ,the hypochlorite dosage was cut from #j4bf-j4ac p4p4m4 of available chlorine and #j4jfe p4p4m4 of ammonia added4 ,economics of the ,chloramine ,process4 ,the chloramine process was introduced at ,ottawa for the purpose of obtaining relief from the effect of the high price of bleach caused by the cessation of imports from ,europe in #aiae4 ,the results obtained with the experimental plant indicated that1 calculated on the prices current at the beginning of #aiag1 appreciable economies could be made4 ,although the reduction in the chlorine dosage has not been as great as was anticipated1 due to the restrictions previously mentioned1 the cost of sterilising chemicals in #aiag was #c1bjj less than the cost of straight hypochlorite treatment4 ,during the latter part of #aiag the relative cost of bleach and ammonia changed 7see ,diagram ,,ix74 ,when calculated on the ,new ,york prices for ,january1 #aiah1 the cost of chloramine treatment in the ,united ,states would be greater than hypochlorite alone unless a large reduction in the dosage could be secured by very long contact periods4 ,this condition is only temporary1 however1 and the price of ammonia will probably gradually decline as the plants for fixation of atmospheric nitrogen commence operations and reduce the demand for the ammonia produced from ammoniacal gas liquor4 ,in ,canada1 the market conditions are still 7#aiah7 favourable to the chloramine process3 bleach is #be per cent higher than the ,u4,s4,a4 product and ammonia can be obtained for one-half the ,new ,york prices4 ,illustration3 ,,diagram ,,ix ,,bleach ,,and ,,ammonia ,,prices ,advantages of the ,chloramine ,process4 ,although the market conditions may1 in some instances1 be unfavourable to the chloramine process1 the method possesses certain advantages that more than offset a slight possible increase in the cost of materials4 ,the taste and odour of chloramine is even more pungent than that of chlorine but since the introduction of the process in ,ottawa no complaints have been received4 ,owing to the reduced dosage1 slight proportional fluctuations in the dosage do not produce the same variations in the amount of free chlorine which is the usual cause of complaints4 ,a public announcement that the amount of hypochlorite has been reduced also has a psychological effect upon the consumers and tends to reduce complaints due to auto-suggestion4 ,the most important advantage of the process is the elimination of the aftergrowth problem4 ,at ,denver1 where the aftergrowth trouble is possibly more acute than at any other city on the continent1 it was effectively banished by the use of chloramine4 ,at ,ottawa1 the sanitary significance of ,b4 coli aftergrowths is no longer of practical interest because such aftergrowths have ceased to occur4 ,whatever may be their opinion as to the sanitary significance of aftergrowths1 all water sanitarians will agree that the better policy is to prevent their occurrence4 ,operation of ,chloramine ,process4 ,for the successful operation of the chloramine process1 the essential factors are low concentrations of the hypochlorite and ammonia solutions4 ,the author has found that hypochlorite containing #j4c-j4e per cent of available chlorine and ammonia containing #j4c-j4e per cent of anhydrous ammonia can be mixed in a #d3a or #h3a ratio without appreciable loss in titre4 ,solutions of these concentrations mixed in #d3a ratio lost only #b-c per cent of available chlorine in fifteen minutes and less than #aj per cent in five hours4 ,the effect of mixing solutions containing #d4ce per cent of available chlorine and #b4b per cent of ammonia is shown in ,table ,,xxx4 ,the stability of chloramine is a function of the concentration and the temperature and in practice it will be found advisable to determine in the laboratory the maximum concentrations that can be used at the maximum temperature attained by the water to be treated 7cf4 ,muspratt and ,smith#f74 ,according to ,raschig#a two competing reactions occur when ammonia is in excess4 7#a7 ,,nh#b;,cl ,,nh#c ,n#b;,h#d;,h,cl hydrazine hydrochloride and 7#b7 #c,,nh#b;,cl #b,,nh#c ,n#b #c,,nh#d;,cl4 ,when the excess of ammonia is large1 as on the addition of ammonia fort1 the second reaction predominates and the yield of nitrogen gas is almost quantitatively proportional to the quantity of available chlorine present4 ,as ammonium chloride has no germicidal action1 and hydrazine a carbolic coefficient of only #j4bd 7,rideal71 the formation of these compounds should be avoided4 ,,table ,,xxx4--,,loss ,,on ,,mixing ,,hypochlorite ,,and ,,ammonia ,hypochlorite containing #d4ce per cent available chlorine4 ,ammonia contained #b4b per cent ,,nh#c ---------------------------------------- -------------------------- ,,loss ,,of ,,available ,,chlorine ,,after ,ratio ,chlorine to ,ammonia by ----------------------------------- ,weight4 ,few ,minutes4 #a ,hour4 #bd ,hours4 ---------------------------------------- ------------------------ ,per cent ,per cent ,per cent #f3a #ai #ai #ai #d3a #bd #be #be #b3a #de #dg #dg #a3a #ia #ia #ib #a3b #bj #bh #fe ---------------------------------------- ------------------------ ,the dosage of chloramine can be checked by titration of the available chlorine 7see p4 #hb7 immediately after treatment or by the estimation of the increment in the total ammonia 7free and albuminoid74 ,routine determinations of the latter made in ,ottawa show that practically the whole 7#ij-ie per cent7 of the added ammonia can be recovered by distillation with alkaline permanganate and that #he-ij per cent is in the free condition4 ,in operating the chloramine process it is important that the pipes used for conveying the chloramine solution should be of ample dimensions and provided with facilities for blowing out the lime that deposits from the solution4 ,ca7,o,cl7#b #b,,nh#c #b,,nh#b;,cl ,ca7,,oh7#b4 ,the marked activity of chloramine as a chlorinating agent could be predicated from its heat of formation1 which is #h1bcj calories4 ,the other possible chloramines should be even more active as the heat of formation of these compounds are3 ,dichloramine ,n,h,cl#b -- #cf1ghj calories4 ,nitrogen trichloride ,n,cl#c -- #fe1ccj calories4 ,dichloramine is unknown but nitrogen chloride has been prepared and is a highly explosive yellow oil that decomposes slowly when kept under water in the ice box4 ,n,cl#c can be easily prepared by passing chlorine gas into a solution of ammonium chloride and this process would suggest that a method might be found of utilising chlorine and ammonia as gases for the production of nitrogen trichloride as a germicide for water chlorination4 ,,nh#d;,cl #c;,cl#b ,n,cl#c #d;,h,cl4 ,the available chlorine content of the chloramines is double the actual chlorine content as each atom of chlorine will liberate two atoms of iodine from hydriodic acid4 ,,nh#b;,cl #b;,,hi ,i#b ,,nh#d;,cl4 ,n,cl#c #f;,,hi #c;,i#b ,,nh#d;,cl #b;,h,cl4 ,,halazone ,for the sterilisation of small individual quantities of water such as are required by cavalry and other mobile troops bleach and acid sulphate tablets have been usually employed4 ,such tablets have given fairly satisfactory results but certain difficulties inherent to these chemicals have made it desirable to seek other methods4 ,the subject was investigated by ,dakin and ,dunham1#g who first tried chloramine-,t 7sodium toluene-p-sulphochloramide74 ,it was found that heavily contaminated waters1 and particularly those containing much carbonates1 required a comparatively high concentration of the disinfectant3 #dj parts per million of chloramine-,t were necessary in some cases and such an amount was distinctly unpalatable4 ,by adding tartaric acid or citric acid the effective concentration could be reduced to #d p4p4m4 but the mixture could not be made into a tablet without decomposition and a two-tablet system was deemed undesirable4 ,toluene sulphodichloramines were next tried4 ,excellent bacteriological results were obtained but the manufacture of tablets again presented difficulties4 ,when the necessary quantity of dichloramine was mixed with what were assumed to be inert salts--sodium chloride for example--the normal slow rate of decomposition was accelerated4 ,the dichloramine1 in tablet form1 was also found to be too insoluble to effect prompt sterilisation4 ,the most suitable substance found by ,dakin and ,dunham was halazone or p-sulphodichloraminobenzoic acid 7,cl#b,n4,o#b,s4,c#f;,h#d4;,,cooh74 ,this compound is easily prepared from cheap readily available materials and was found to be effective and reasonably stable4 ,the starting point in the preparation of halazone is p-toluenesulphonic chloride1 a cheap waste product in the manufacture of saccharine4 ,by the action of ammonia1 p-toluene sulphonamide is produced and is subsequently oxidised by bichromate and sulphuric acid to p-sulphonamidobenzoic acid4 ,this acid1 on chlorination at low temperatures1 yields p-sulphondichloraminobenzoic acid 7halazone74 ,the reactions may be expressed as follows3 ,,ch#c ,,cooh ,,cooh _/ _/ _/ -- -- _/ _/ _/ ,,so#b4,,nh#c ,,so#b4,,nh#b ,,so#b4,n,cl#b ,halazone is a white crystalline solid1 sparingly soluble in water and chloroform1 and insoluble in petroleum4 ,it readily dissolves in glacial acetic acid from which it crystallizes in prisms 7,m4,p4 #bac deg4 ,c474 ,the purity of the compound can be ascertained by dissolving in glacial acetic acid1 adding potassium iodide1 and titrating with thiosulphate2 #j4a gram should require #ad4h to #ad4i c4cms4 of ,n_/#aj sodium thiosulphate4 ,each chlorine atom in halazone is equivalent to #a molecule of hypochlorous acid and the available chlorine content is consequently #eb4e per cent or double the actual chlorine content4 ,,so#b4,n,cl#b #d;,,hi ,,so#b4,,nh#b #b;,h,cl #b;,i#b4 ,from the bacteriological results given by ,dakin and ,dunham it would appear that #c parts per million of halazone 7#a4e p4p4m4 available chlorine7 are sufficient to sterilise heavily polluted waters in thirty minutes and that this concentration can be relied upon to remove pathogenic organisms4 ,the formula recommended for the preparation of tablets is halazone #d per cent1 sodium carbonate1 #d per cent 7or dried borax #h per cent71 and sodium chloride 7pure7 #ib per cent4 ,halazone and halazone tablets1 when tested in the author's laboratory on the coloured ,ottawa ,river water seeded with ,b4 coli1 have given rather inferior results4 ,with #a tablet per quart1 over six hours were required to reduce a ,b4 coli content of #ajj per #aj c4cms4 to less than #a per #aj c4cms4 ,clear well waters gave excellent results and large numbers of ,b4 coli were reduced to less than #a per #aj c4cms4 in less than thirty minutes4 ,mc,crady,a has also obtained excellent results with various strains of ,b4 coli seeded into the colourless ,st4 ,lawrence water4 ,a ,private communication4 ,,bibliography #a ,raschig4 ,chem4 ,zeit41 #aijg1 #ca1 #ibf4 #b ,rideal4 ,s4 ,j4 ,roy4 ,san4 ,inst41 #aiaj1 #ca1 #cc-de4 #c ,race4 ,j4 ,amer4 ,waterworks ,assoc41 #aiah1 #e1 #fc4 #d ,race4 ,eng4 and ,contr41 #aiag1 #dg1 #bea4 #e ,contract ,record4 ,aug4 #ae1 #aiag1 #fif4 #f ,muspratt and ,smith4 ,j4 ,soc4 ,chem4 ,ind41 #ahih1 #ag1 #ebi4 #g ,dakin and ,dunham4 ,brit4 ,med4 ,jour41 #aiag1 ,no4 #bidc1 #fhb4 ,,chapter ,x ,,results ,,obtained ,the object of adding chlorine or chlorine compounds to water is for the purpose of destroying any pathogenic organisms that may be present4 ,in a few instances some collateral advantages are also obtained but1 in general1 no other object is aimed at or secured4 ,chlorination does not change the physical appearance of water2 it does not reduce or increase the turbidity nor does it decrease the colour in an appreciable degree4 ,the chemical composition is also practically unaltered4 ,when bleach is used there is a proportionate increase in the hardness but the amount is usually trifling and is without significance4 ,during #aiaf when the ,ottawa supply was entirely treated with bleach at the rate of #b4g parts per million 7#j4ib p4p4m4 of available chlorine7 the average increase in the total hardness as determined by the soap method was #b4e parts per million4 ,when chlorine is added to prefiltered water1 as an adjunct to filtration1 an increase in the number of gallons filtered per run has been noted at some plants4 ,this increase is not so great with rapid as with slow sand filters but in some instances it has led to appreciable economies4 ,walden and ,powell#a of ,baltimore1 found that the addition of a quantity of bleach equal to approximately #j4ej p4p4m4 of available chlorine enabled the alum to be reduced from #j4hg to #j4eh grain per gallon4 ,the percentage of water used in washing the filters was also reduced1 from #d4a per cent to #b4i per cent1 whilst the filter runs were increased on the average by one hour and ten minutes4 ,the net saving in coagulant alone amounted to #cj cents per million gallons4 ,clark and ,de ,gage#b found that the use of smaller amounts of coagulant during the period of combined disinfection and coagulation resulted in an increase of nearly #be per cent in the quantity of water passed through the filter between washings1 and also in a material reduction of the cost of chemicals1 which averaged #b4fb per million gallons for combined disinfection and coagulation as against #d4hf for coagulation alone4 ,the water used in these experiments was obtained from the ,merrimac ,river at ,lawrence4 ,the effect of hypochlorite on the reduction of algae growths on slow sand filters was first noticed by ,houston during the treatment of the ,lincoln supply in #aije4 ,two open service reservoirs were fed with treated water and were themselves dosed from time to time4 ,previous to #aije they developed seasonally most abundant growths1 but during the hypochlorite treatment it was noticed that they remained bright1 clear1 and remarkably free from growths 7,houston#c74 ,ellms1#d of ,cincinnati1 has also noted the effect of hypochlorite on algae4 ,when the bleach was added to the coagulated water the destruction of the plankton was not as satisfactory as had been anticipated and it was found that large doses destroyed the coating of the sand particles and rendered the filters less efficient4 ,the use of bleach in the filtered water basin was more successful and cleared it of troublesome growths4 ,in #aiaf1 during the treatment of the ,london ,supply with bleach 7dosage #j4e p4p4m4 of available chlorine71 ,houston made further observations on this point4 ,the ,thames water1 taken at ,staines1 had previously been stored for considerable periods in reservoirs1 but this necessitated lifting the water by pumps which consumed large quantities of coal that were urgently needed for national purposes4 ,as a war measure1 the storage was eliminated and the water treated with hypochlorite at ,staines and allowed to flow by gravitation to the various works where the slow sand filters are situated4 ,the treatment resulted in a marked reduction in the growths of algae1 the reduction in the area of filters cleaned in #aiaf 7,june to ,september7 as compared with #aiae being as follows3 ,percentage ,filter ,works4 ,reduction 7,approximate74 ,grand ,junction 7,hampton7 #f ,grand ,junction 7,kew7 #dc ,east ,london 7,sunbury7 #cj ,kempton ,park #cc ,west ,middlesex #ef ,a portion of this reduction can probably be attributed to the elimination of storage4 ,chlorination1 by decreasing the load on filter beds1 has enabled the rate of filtration to be increased in some cases4 ,this increased capacity1 which would otherwise have necessitated additional filter units1 has been obtained without any further capital outlay4 ,at ,pittsburg 7,johnson#e7 the rate of filtration1 after cleaning1 was increased #bej1jjj gallons each hour until the normal rate was reached2 restored beds were maintained at a #bej1jjj gallon rate for one week4 ,after the introduction of chlorination it was found possible to increase the rates more rapidly without adversely affecting the purity of the mixed filter affluents4 ,hygienic ,results4 ,evidence as to the actual reduction of the number of such pathogenic germs as ,b4 typhosus in water supplies by chlorination is most readily found in the death rates from typhoid fever in cities that have no other means of water purification4 ,in some cases this evidence is necessarily of a circumstantial nature2 in others it is definite and conclusive4 ,some of the earlier results of the effect of chlorination on typhoid morbidity and mortality rates were compiled by ,jennings#f and others have been published by ,longley4#g ,these data have been brought up to date in ,table ,,xxxi and other statistics added4 ,,table ,,xxxi4--,,effect ,,of ,,chlorination ,,on ,,typhoid ,,rates ,,average ,,typhoid ,,death ,,rate ,,per #ajj1jjj ,,population ---------------------------------------- ---------------------------- ,city4 ,commenced ,,before ,,using4 ,,after ,,using4 ,chlorination4-------------------------- ,percentage ,period4,rate4 ,period4,rate4 ,reduction4 ---------------------------------------- -------------------------- ,baltimore ,june #aiaa #aijj-aj #ce4b #aiab-ae #bb4b #cf ,cleveland ,sept4 #aiaa #aijj-aj #ce4e #aiab-af #h4b #gg ,des ,moines ,dec4 #aiaj #aije-aj #bb4g #aiaa-ac #ac4d #da ,erie ,mar4 #aiaa #aijf-aj #ej4f #aiab-ad #ae4j #gj ,evanston1 ,ill4 ,dec4 #aiaa #aijh-aa #bi4j #aiab-ac #ad4e #ej ,jersey ,city ,sept4 #aijh #aijj-ag #ah4g #aiji-af #h4d #ee ,kansas ,city1 ,mo4,jan4 #aiaa #aijj-aj #db4e #aiaa-af #ad4b #ff ,omaha1 ,neb4 ,may #aiaj #aijj-ji #bb4e #aiaa-af #aj4f #ec ,trenton ,dec4 #aiaa #aijg-aa #df4j #aiaa-ad #bh4g #ce ,montreal ,feb4 #aiaj #aijf-aj #dj4j #aiaa-af #be4j #cg ,toronto ,apr4 #aiaa #aijf-aj #ca4b #aiab-af #g4h #ge ,ottawa ,sept4 #aiab #aijf-aj #cd4j #aiac-ag #ag4j #ej ---------------------------------------- -------------------------- ,the figures given in this table show the effect of chlorination only2 no other form of purification was used during the periods given1 except at ,toronto where a portion of the supply has been subjected to filtration4 ,it will be seen that since chlorination was adopted the typhoid death rates have been reduced by approximately #ej per cent and that the averages for the period after treatment are almost invariably less than #bj per #ajj1jjj1 a figure that a few years ago was regarded as satisfactory4 ,the average death rate for the last available year is #aa per #ajj1jjj1 a result that is even more satisfactory and exceeds the anticipations of the most optimistic of sanitarians4 ,a portion of the reduction in the typhoid rates is no doubt due to improvements in general sanitary conditions but the reduction is much greater than can be accounted for in that manner alone and in many cases there was a sharp decline immediately following the commencement of chlorination4 ,in a few instances there is evidence that chlorination has reduced the typhoid rates of cities previously supplied with filtered water4 ,diagram ,x1 drawn from data supplied by ,dr4 ,west1 of the ,torresdale ,filtration ,plant1 shows the effect of disinfecting the filter effluents at ,philadelphia4 ,illustration3 ,,diagram ,x ,,typhoid ,,in ,,philadelphia ,during the years #aiji-aj-aa1 when practically the whole of the city supply was filtered1 the average typhoid death rate was #ah1 but when the water was also chlorinated1 in #aiad-ae-af1 the rate was only #g1 a reduction of #fa per cent4 ,the figures in ,table ,,xxxii show that the ,torresdale filters1 during #aiae-af were unable to adequately purify the water and that chlorination was necessary4 ,,table ,,xxxii4--,,chlorination ,,of ,,filter ,,effluents 7,,torresdale7 ---------------------------------------- -------------------------- ,,bacteria ,,per ,,cubic ,,centimeter4 ,oxygen --------------------------------- ,consumed4 ,colour4 ,turbidity4 ,untreated4 ,treated4 ------------------------------- ,gelatine4 ,agar4 ,gelatine4 ,agar4 ---------------------------------------- ----------------------- #aiae #a4gj #ab #j4f #ada #cj #bh #ad #aiaf #a4ij #ab ,nil4 #hh #bc #ch #aa ,b4 coli communis ,per ,cent ,positive ,tests4 ---------------------------------------- ------- ,untreated4 ,treated4 ,added ,chlorine ---------------------------------------- ----- ,parts ,per #aj c4cms4 #a c4cm4 #aj c4cms4 #a c4cm4 ,million4 ---------------------------------------- ------------------------- #aiae #ff #bd #e #j4c #j4ah #aiaf #di #af #g4d #a4i #j4ae ---------------------------------------- ------------------------- ,in ,diagram ,,xi the typhoid death rates of ,columbus1 ,ohio1 and ,new ,orleans are shown to exemplify conditions that have not been improved by chlorination4 ,the endemic condition of typhoid in ,columbus was brought to an abrupt conclusion by the installation and operation of the softening and filter plant in ,september1 #aijh1 and no further reduction followed the introduction of chlorination in ,december1 #aiji4 ,in ,new ,orleans the typhoid rate decreased on the inception of the new water works system in #aiji and again after the installation of the ,carrollton filters in #aiab4 ,the product of the filtration plants has always been above suspicion but aftergrowths occasionally developed and the bacterial count then exceeded the ,united ,states ,treasury standard4 ,to overcome this difficulty1 hypochlorite was used in #aiae1 but1 as was anticipated1 it had no effect on the typhoid rate4 ,the high rate in ,new ,orleans is largely due to outside cases received for hospital treatment and to other circumstances beyond the control of the water and sewerage department4 ,in all the examples previously cited1 the evidence as to the effect of chlorination on typhoid mortality rates is circumstantial but1 taken as a whole1 it is fairly conclusive4 ,in the examples to be considered next the evidence is more direct4 ,illustration3 ,,diagram ,,xi ,,typhoid ,,in ,,columbus ,,and ,,new ,,orleans ,one of the most conclusive experiments as to the beneficial effect of chlorination is that reported by ,young#h of ,chicago4 ,the water supply of ,chicago was obtained from ,lake ,michigan by means of intake pipes and pumped to various parts of the city4 ,the distribution system was divided into four districts and1 although there was a certain amount of mixing along the borders1 the water supplied to each district was substantially separate4 ,the rapid and progressive decline in the typhoid rate of ,chicago 7from #ai in #aijj to #aj4h in #aiaa7 subsequent to the diversion of the city sewage from the lake1 led to the assumption that water-borne typhoid had ceased to be of any moment4 ,early in #aiab1 however1 permission was secured to chlorinate the supply of one district 7,no4 #a7 and the treatment was continued until ,december when the solutions commenced to freeze4 ,diagram ,,xii shows the effect of the treatment on the autumnal increase in ,district ,no4 #a as compared with the other three districts4 ,the autumnal increase was calculated from the excess of typhoid incidence for ,july to ,november inclusive1 over that for ,february to ,june inclusive4 ,illustration3 ,,diagram ,,xii ,,autumnal ,,increase ,,in ,,typhoid1 ,,chicago 7,young7 ,these results demonstrate in a most striking manner the beneficial effect of chlorination4 ,the general conditions1 with the exception of the raw water supply1 were approximately the same in all four districts4 ,diagram ,,xiii shows that the raw water supply of ,district ,no4 #a was slightly worse than any of the others1 #ba4h per cent of the samples from ,district ,no4 #a containing ,b4 coli in #a c4cm4 as compared with #ba4j per cent in the most polluted supply of the other districts4 ,illustration3 ,,diagram ,,xiii ,b4 ,,coli ,,in ,,chicago ,,raw ,,water 7,young7 ,the results obtained at ,ottawa are also conclusive4 ,following two epidemics of typhoid fever in #aiaa and #aiab1 caused by breaks in the intake pipe1 hypochlorite treatment was commenced and has been in continuous operation until ,february1 #aiag1 when chloramine treatment was substituted4 ,the dosage has been so regulated as to assure a high degree of purity at all times in the water delivered to the mains and as evidence of this it might be mentioned that the average ,b4 coli index 7calculated by ,phelps' method7 for the years #aiaf and #aiag was only #j4bg per #ajj c4cms4 ,the typhoid rates for the five years preceding the epidemic years and for a similar subsequent period are given in ,diagram ,,xiv4 ,illustration3 ,,diagram ,,xiv ,,typhoid ,,in ,,ottawa ,the diagram shows that there has been a constant reduction in the city typhoid rate since the last severe epidemic with the exception of the year #aiae4 ,the high rate of that year was caused by a localised epidemic started by polluted well water and spread by flies from an unsewered area4 ,this outbreak was the cause of about seven deaths registered during that year 7population #ajj1jjj74 ,the objection might be raised that if the reduction of the typhoid rate were due to the water treatment1 the decline should have been abrupt and not a gradual one4 ,it is probable that there has been practically no water-borne typhoid in the city since chlorination was commenced but this fact is masked by cases from other sources4 ,during #aiaa and #aiab over #c1ejj cases of typhoid were reported1 of which an appreciable number would become carriers for various periods of time4 ,as these carriers decreased the number of cases infected by them would also decrease and so account for a gradually declining death rate4 ,it might be further objected that the reduced typhoid rate is due to a general improvement in the sanitary conditions4 ,if the death rate from causes other than typhoid can be regarded as a measure of the general sanitary conditions it is obvious from the data in ,table ,,xxxiii that the improvement in the typhoid rate is immeasurably greater than can be ascribed to that cause4 ,,table ,,xxxiii4--,,death ,,rates ,,in ,,ottawa ,,before ,,and ,,after ,,chlorination ---------------------------------------- -------------------------- ,,rate ,,per #ajj1jjj ,,percentage ,cause4 -------------------------------------- #aijh-ab #aiac-ag ,reduction ,increase ---------------------------------------- ------------------------ ,total,a #ad4ij #ad4gh #a4b 444 ,typhoid1 total #cd;,b #ag #ej4j 444 ,typhoid1 city #bf;,b #h #fi4b 444 ,pneumonia #ajj #ajg 444 #g4j ,tuberculosis #acc #ach 444 #c4g ,diarrhoea and ,enteritis #aci #abh #g4i 444 under #b years ---------------------------------------- ------------------------ ,a ,rate per #a1jjj4 ,b #aijf-aj1 epidemic years #aiaa-ab excluded4 ,one further objection might be made3 that the raw water was not infected during #aiac-ag or infected to a smaller extent than during the previous period4 ,attempts to isolate ,b4 typhosus from the raw water have invariably been futile but their presence in #aiad might be inferred from the fact that during the latter part of the summer of that year an epidemic of typhoid fever occurred at ,aylmer1 a village that discharges its sewage into the ,ottawa ,river about six miles above the ,ottawa intake4 ,hull1 situated on the opposite bank of the river and having a population of #bj1jjj1 takes its water supply from the same channel that supplies ,ottawa but at a point a few hundred feet further down stream4 ,during ,november and ,december1 #aiad1 some #bjj cases of typhoid fever 7incidence #a1jjj per #ajj1jjj7 occurred in ,hull as compared with #bh in ,ottawa4 ,as the ,ottawa intake is situated between the ,hull intake and the outlet of the ,aylmer sewer it is incredible that the ,ottawa raw water was not also infected4 ,in #aiaf a liquid chlorine plant was installed in ,hull1 but in #aiag1 owing to an accident1 it was out of commission for a short period and at least #ajj cases of fever developed during the following month4 ,during the same period only two cases were reported in ,ottawa and of these one was obviously contracted outside the city4 ,in view of the preceding facts it must be granted that the improvement in the typhoid rate of ,ottawa can be definitely attributed to an improvement in the water supply caused by chlorination4 ,the efficacy of chlorination to prevent and check epidemics of water-borne typhoid has never been doubted4 ,innumerable instances could be cited in which the prompt treatment of large public supplies has promptly checked outbreaks that threatened to assume serious proportions and there is no doubt that the extremely low typhoid morbidity rate on the ,western ,front of the ,european battlefield is partially due to the extensive and rigorous chlorination measures that have been instigated4 ,prophylactic vaccination and the prompt isolation of typhoid carriers have largely contributed to the wonderful results obtained but due credit must also be given to the systematic purification and treatment of water supplies4 ,similar results have been obtained at training camps in ,canada and in other countries by effective treatment with either liquid chlorine or hypochlorite4 ,since the inception of water chlorination in ,america in #aijh1 the merit of the method has been very generally recognized throughout the ,continent but was regarded with scepticism in ,europe1 except as a temporary expedient1 until the results obtained by the military forces compelled more general recognition4 ,before the war1 chlorination of water supplies in ,england was only practised in a few isolated and relatively unimportant instances2 in #aiag1 practically the whole supply of ,london was chlorinated and at ,worcester a similar treatment has been recommended to enable the slow sand filters to be operated at higher rates without reducing the quality of the water supplied to the consumers4 ,use and ,abuse of ,chlorine4 ,inasmuch as chlorination has no beneficial effect on water except the reduction of the bacterial content it should be used for this purpose only and under such conditions as permit the operations to be under full control at all times4 ,the supplies that can be most efficiently and safely treated are those that are relatively constant in chemical composition and bacterial pollution4 ,changes in volume can be dealt with by automatic apparatus but sudden changes in organic and bacterial content require a change of dosage that cannot be made by any mechanical appliance4 ,long experience and accurate meteorological records may in some cases enable those in charge of chlorination plants to anticipate changes in the conditions of the water supply1 but it is always preferable to provide a positive method of preventing sudden changes by using chlorination merely as an adjunct to other processes of purification4 ,unpurified waters that are objectionable on account of their bacterial content only are very rare1 as the cause that produces the bacterial pollution usually produces other conditions that are equally objectionable though not so dangerous to health4 ,sudden storms in summer1 or sudden thaws in winter1 usually cause large increments in turbidity accompanied by soil washings that often carry appreciable quantities of faecal matter into surface water supplies4 ,lake supplies often suffer in the same manner and sewage1 which during normal conditions is carried safely away from water intakes1 obtains access to the supply4 ,if the dosage is maintained at a level sufficiently high to meet these abnormal conditions1 complaints as to taste and odour would ensue1 and in general1 such a practice is impossible4 ,some supplies have been chlorinated successfully for years but the principle of using chlorination as the first and last line of defence cannot be recommended4 ,success can only be obtained by eternal vigilance and the responsibility for results is more than water works officials should be called upon to assume4 ,chlorination is an invaluable adjunct to other forms of water purification and it is not improbable that1 in the future1 filter plants will be designed to remove aesthetic objections at the lowest possible cost and that chlorination will be relied upon for bacterial reduction4 ,chlorination is the simplest1 most economical1 and efficient process by which the removal of bacteria can be accomplished and there is no valid reason why it should not be used for that purpose4 ,the popularity of this process has suffered through the efforts of over zealous enthusiasts who have been unable either to recognize its limitations or to appreciate the fact that a domestic water supply should be something more than a palatable liquid that does not contain pathogenic organisms4 ,every system of water purification has its limited sphere of utility and chlorination is no exception to the rule4 ,,bibliography #a ,weldon and ,powell4 ,eng4 ,rec41 #aiaj1 #fa1 #fba4 #b ,clark and ,de ,gage1 #dast ,annual ,rpt4 ,mass4 ,state ,b4 of ,h4 #aiaj4 #c ,houston4 #abth ,research ,rpt4 ,metropolitan ,water ,board1 ,london4 #d ,ellms4 ,eng4 ,rec41 #aiaa1 #fc1 #chh4 #e ,johnson4 ,eng4 ,rec41 #aiaa1 #fd1 ,no4 #af4 #f ,jennings4 #hth ,inter4 ,congr4 ,appl4 ,chem41 #bf1 #bae4 #g ,longley4 ,j4 ,amer4 ,waterworks ,assoc41 #aiae1 #b1 #fgi4 #h ,young4 ,j4 ,amer4 ,public ,health ,assoc41 #aiad1 #d1 #caj4 ,,appendix ,,estimation ,,of ,,chlorine ,,in ,,chlorinated ,,waters ,,reagents4 #a4 ,tolidine solution4 ,one gram of o-tolidine1 purified by recrystallization from alcohol1 is dissolved in #a litre of #aj per cent hydrochloric acid4 #b4 ,copper sulphate solution4 ,dissolve #a4e grams of copper sulphate and #a c4cm4 of concentrated sulphuric acid in distilled water and dilute the solution to #ajj c4cms4 #c4 ,potassium bichromate solution4 ,dissolve #j4jbe gram of potassium bichromate and #j4a c4cm4 of concentrated sulphuric acid in distilled water and dilute the solution to #ajj c4cms4 ,,procedure4 ,mix #a c4cm4 of the tolidine reagent with #ajj c4cms4 of the sample in a ,nessler tube and allow the solution to stand at least five minutes4 ,small amounts of free chlorine give a yellow and larger amounts an orange colour4 ,for quantitative determination compare the colour with that of standards in similar tubes prepared from the solutions of copper sulphate and potassium bichromate4 ,the amounts of solution for various standards are indicated in the following table3 ,,preparation ,,of ,,permanent ,,standards ,,for ,,content ,,of ,,chlorine ---------------------------------------- ---------------------- ,chlorine4 ,solution of ,solution of ,copper ,sulphate4 ,potassium ,bichromate4 ,parts per million4 c4cms4 c4cms4 ---------------------------------------- ---------------------- #j4ja #j4j #j4h 4#jb #j4j #b4a 4#jc #j4j #c4b 4#jd #j4j #d4c 4#je #j4d #e4e 4#jf #j4h #f4f 4#jg #a4b #g4e 4#jh #a4e #h4g 4#ji #a4g #i4j 4#aj #a4h #aj4j 4#bj #a4i #bj4j 4#cj #a4i #cj4j 4#dj #b4j #ch4j 4#ej #b4j #de4j ---------------------------------------- ---------------------- ,illustration3 ,,diagram ,,xv ,illustration3 ,,diagram ,,xvi ,,name ,,index ,a ,adams1 #ff1 #hb ,b ,bassenge1 #i ,baxter1 #d ,berge1 #i ,berthollet1 #a ,bevan1 #bi ,bonjean1 #cf ,bray1 #bd ,breteau1 #bf ,bucholtz1 #e ,c ,catlett1 #ii ,clark1 #ec1 #acc ,comte1 #dg ,cross1 #bi ,cruikshank1 #c ,d ,dakin1 #bb1 #bh1 #abi ,darnall1 #hi ,davy1 #a ,de,gage1 #ec1 #acc ,de,morveau1 #c ,dibden1 #f ,dienert1 #dh ,dienheim-,brochoki1 #aje ,dowell1 #bd ,dunbar1 #f ,dunham1 #abi ,dupre1 #e ,dusch1 #d ,e ,ellms1 #cd1 #hc1 #hd1 #acc ,elmanovitsch1 #cf ,elsner1 #f ,evans1 #hd ,f ,faraday1 #ajc ,fischer1 #af ,forcrand1 #ajc ,fuller1 ,g4 ,w41 #aa ,g ,gascard1 #dg ,griffen1 #ag1 #gi ,h ,haberkorn1 #e ,hale1 #hj1 #ajj ,harrington1 #cd1 #fe ,hauser1 #hc1 #hd ,hedallen1 #ag1 #gi ,heise1 #cf ,henry1 #b ,hermite1 #e ,hewlett1 #i ,hooker1 #gb ,horrocks1 #dh ,houston1 #h1 #ei1 #ga1 #acc ,hsu1 #ba ,j ,jackson1 #ia1 #ii ,jakowkin1 #bf ,jennings1 #ace ,johnson1 #aa1 #acd ,jordan1 ,h4 ,e41 #eg ,k ,kanthack1 #f ,kauffman1 #i ,kellerman1 #g ,kershaw1 #ajg ,kienle1 #fe1 #ff1 #ij1 #ii ,kimberly1 #g ,klein1 #e ,koch1 #d ,kolessnikoff1 #af ,kranejuhl1 #g ,kuhn1 #e ,kurpjuivat1 #g ,l ,landolt1 #aje ,langar1 #aj ,laroche1 #dg ,lavoisier1 #a1 #ae ,leal1 #af ,lehmann1 #aja ,le,roy1 #hc ,letton1 #fd ,longley1 #dc1 #ace ,lunge1 #aje ,lyon1 #bd ,m ,marshall1 #ajb ,massy1 #dh ,meadows1 #aab1 #aad ,mc,crady1 #acj ,mc,gowan1 #h ,mc,lintock1 #e ,mohler1 #ca ,mohr1 #gi ,moor1 #i ,muspratt1 #abf ,n ,nesfield1 #h1 #hi ,nissen1 #cj ,norton1 #ba ,novey1 #bc ,noyes1 #bd ,o ,ornstein1 #ij ,orticoni1 #cf ,p ,pedler1 #ajc ,percy1 #c ,pettenkofer1 #aja ,phelps1 #g1 #ag1 #hb ,pitcher1 #aab ,plucker1 #aj ,powell1 #acb ,pratt1 #g ,proskauer1 #f1 #af ,r ,rabs1 #aaj ,race1 #cf1 #aaj1 #aaf ,raschig1 #aae ,rickard1 #ajh ,rideal1 ,e4 ,k41 #hd ,rideal1 ,s41 #f1 #i1 #ba1 #bb1 #fj1 #aae1 #aaf ,roscoe1 #e ,roozeboom1 #ajc ,rouquette1 #cf ,ruffer1 #e ,s ,sandman1 #ef ,scheele1 #a1 #ae ,schroder1 #d ,schuder1 #aj ,schumacher1 #g ,schumburg1 #aj ,schwann1 #d ,schwartz1 #g ,semmelweiss1 #d ,sickenberger1 #i ,smeeton1 #ec ,smith1 #abf ,t ,tennant1 #b ,thomas1 #ec1 #ef ,thresh1 #hg ,tiernan1 #ib ,tolman1 #aaa ,traube1 #i ,v ,valeski1 #cf ,von ,loan1 #ij ,w ,walden1 #acb ,walker1 #hg ,wallace1 #ib ,wallis1 #hc ,warouzoff1 #af ,watt1 #b1 #c1 #ae1 #ajf ,webster1 #e1 #aje ,wesbrook1 #ca1 #dd1 #ec ,west1 #ia1 #ii1 #acf ,whittaker1 #ca ,winkler1 #hd ,winogradoff1 #af ,winslow1 #aaj ,woodhead1 #g ,woolf1 #e ,y ,young1 #ach ,z ,zirn1 #f ,,subject ,,index ,a ,absorption of chlorine by water1 #ce ,abuse of chlorination1 #add ,acids1 effect of1 #ai1 #ba ,action of chlorine1 #af ,admixture1 effect of1 #ci ,aftergrowths1 #ee accelerated growth1 #eh ,b4 coli in1 #eg effect of liquid chlorine1 #ii views as to nature of1 #ef ,algae1 effect of chlorine on1 #acc ,alkalies1 effect of1 #ai1 #bj ,allen-,moore cell1 #aaa ,ammonia1 and chlorine1 #bd and sodium hypochlorite1 #aad effect on bleach1 #ba effect on oxidising action1 #ba soda process1 #b ,antichlors1 #hf ,antiseptics1 early work on1 #c chlorine as an1 #ej ,application of chlorine1 point of1 #dc ,auto-suggestion1 #fb ,b ,b4 cholerae suis1 #ca ,b4 cloacae1 #ca ,b4 coli1 aftergrowths1 #eg in sewage1 #f1 #g in water1 #i1 #bh1 #ca standard1 #df viability of1 #eb1 #ee ,b4 cuticularis1 #ec ,b4 faecalis alkaligenes1 #ca ,b4 enteritidis1 #ca ,b4 enteritidis sporogenes1 #ec ,b4 lactis aerogenes1 #ca ,b4 subtilis1 #ec ,b4 tetani1 #i ,b4 typhosus1 #i1 #aj1 #cj1 #ca ,bacteria surviving chlorination1 #ej aftergrowths1 #ee nature of1 #ec spores1 #eg ,benzidine1 #hc ,bleach1 analysis of solution1 #gi as deodourant1 #c1 #f as sewage disinfectant1 #f1 #g at ,adrian1 #aa at ,boonton1 #aa1 #af at ,bubbly ,creek1 #aa composition1 #ad decomposition of1 #be discovery1 #b germicidal velocity1 #bj1 #ba hydrolysis1 #ah1 #ai production1 #c stability of1 #ag toxic action1 #bb treatment1 #gb control of1 #gh cost1 #hf dosage regulation1 #ge in ,france1 #gh losses in1 #ha mixing tank1 #gc plant design1 #gb storage tank1 #ge ,brest experiments1 #e ,c ,carnallite1 #a ,chicago1 typhoid rate1 #ach ,chloramine1 #aad at ,denver1 #abd1 #abf at ,ottawa1 #bh1 #aaf contact period1 #abc cost of1 #abd decomposition of1 #abf experimental results1 #aai germicidal power1 #aaf operation of process1 #abf plant design1 #abj preparation of1 #aae ratio of chlorine and ammonia1 #aaf1 #abb tastes and odours1 #bh1 #fd1 #aag toxic action1 #bb1 #bi ,chlorides1 effect of1 #bj ,chlorine1 and ammonia1 #bd1 #be discovery of1 #a disinfection1 effect of pabulum1 #d general reactions1 #bh hydrate1 #ajc detection of1 #ha effect on flowers1 #fh estimation of1 #ha in sanitary work1 #d medicinal dose1 #fg oxygen equivalent1 #bc liquid1 #hi advantages of1 #ig cost of treatment1 #aja disadvantages of1 #aja germicidal efficiency1 #ii machines1 #hi peroxide1 #i water1 #ajb corrosion of pipes1 #fi damage to seeds1 #fh decomposition of1 #ae heat of formation1 #bg ,chlorometer1 #hd ,chloros1 #h ,chlorozone1 #aje ,colour1 effect on dosage1 #cc ,columbus1 typhoid rates1 #acg ,complaints1 #fb ,contact period1 effect on dosage1 #dd effect on taste1 #dc usual practice1 #de ,cost of bleach plant1 #he bleach treatment1 #hf liquid chlorine treatment1 #aja ,crossness experiments1 #e ,d ,dayton cell1 #ajg ,de,chlor filters1 #hg ,denver1 chloramine treatment1 #abd1 #abf ,dichloramine1 #abh ,disinfectants1 #ej ,disinfection1 early views of1 #c ,dosage1 #cj determination of1 #df effect of1 admixture1 #ci colour1 #cc contact period1 #dc initial contamination1 #cb light1 #de oxidisable matter1 #cb standard of purity1 #cj1 #cb temperature1 #cd1 #cf turbidity1 #de for military work1 #dh regulation of bleach1 #ge relation to oxygen absorbed1 #cf tanks1 #ge ,e ,eau de ,javelle1 #c1 #dg ,electrical conductivity of treated water1 #gj ,electrolysed sea water1 #e ,electrolytic hypochlorite1 #b1 #ajd ,bradford1 #e ,brest1 #e ,brewster1 #f1 #aje cost of1 #aac ,electrolytic hydrochlorite1 ,crossness1 #e discovery of1 #c diaphragm cells1 #aaj early use of1 #e efficiency of1 #aji ,havre1 #e non-diaphragm cells1 #ajf ,electrozone1 ,brewster1 #f ,maidenhead1 #f ,tonetta ,creek1 #f ,f ,filter effluents1 chlorination of1 #cd ,filters1 effect on beds1 #fj effect on runs1 #acb ,fish1 effect on1 #h1 #fg1 #fh ,g ,germicidal velocity1 effect of acids1 #ba alkalies1 #bj ammonia1 #ba chlorides1 #bj ,guildford1 chlorination at1 #i ,h ,haas and ,oettel cell1 #ajh ,halazone1 #abh ,hardness1 effect of chlorine on1 #acb ,havre experiments1 #e ,hermite fluid1 #e ,hexamethyl-p-aminotriphenylmethane1 #hc ,historical1 #a ,hooghly ,river1 #g ,hydrazine1 #abf ,hydrogen peroxide1 #bd ,hydrolysis of hypochlorites1 effect of1 acids1 #ai alkalies1 #ai chlorides1 #bj ,hygienic results1 #acd ,hypochlorous acid1 #ag decomposition of1 #bd1 #be1 #bf hydrolytic constant1 #ah ,i ,initial contamination1 effect on dosage1 #cb ,intestinal organisms1 viability of1 #eb ,iodoform taste1 #fe ,iron salts1 effect on dosage1 #cc ,j ,jersey ,city1 court case1 #aa1 #af ,k ,kellner cell1 #ajh ,l ,labarraque solution1 #aje ,leavitt-,jackson machine1 #ia ,leblanc process1 #b ,light1 effect on dosage1 #de ,lincoln1 chlorination at1 #h1 #ei ,liquid chlorine1 advantages of1 #ig and tastes1 #fe effect of temperature on1 #ie machines1 #hi dry feed1 #id ,e4 ,b4 ,g4 ,co41 #ia ,leavitt-,jackson1 #ia operation of1 #ie ,wallace and ,tiernan1 #ib ,l',orient1 experiments at1 #e ,m ,m4 agilis1 #ec ,maidstone1 use of bleach at1 #h ,margin of safety for taste and odour1 #fd ,material for bleach plants1 #gd ,military work1 bleach method for1 #gh chlorine water1 #ajc dosage for1 #dg1 #dh1 #gh early ,european1 #aj liquid chlorine1 #ajb typhoid reduction1 #adc use of chlorine in1 #h ,mixing tank for bleach1 #gc ,moisture1 effect on chlorine gas1 #af ,montreal1 dosage at1 #cd electrolytic cells1 #aab ,n ,nascent oxygen hypothesis1 #ag ,nelson cell1 #aaa ,neva ,river1 #cf ,new ,orleans1 typhoid rates1 #acg ,new ,york1 bacteria surviving treatment1 #ec bleach efficiency1 #ajj liquid chlorine plant1 #ig ,nitrites1 effect on dosage1 #cc ,nitrogen trichloride1 #bd1 #abh ,o ,odours1 effect of contact period on1 #dc nature of1 #fc ,ottawa1 aftergrowths at1 #eg bleach plant efficiency1 #ajj chloramine plant1 #abj chloramine results1 #aba sludge trouble1 #fe typhoid rates1 #adj ,oxidisable matter1 effect on dosage1 #cb1 #cf ,oxychloride1 ,guildford1 #i ,middlekerke1 #i ,ostend1 #i ,ozone1 #bd ,p ,philadelphia and chlorination1 #acf ,pipe corrosion1 #fi ,pittsburg report1 #ga ,plumbo solvency1 #ga ,p4 mirabilis1 #ca ,potassium permanganate1 #bc ,puerperal fever in ,vienna1 #d ,pumps1 for admixture1 #da ,r ,red ,bank1 sewage disinfection at1 #g ,reversed ratio of counts1 #ed ,s ,sewage disinfection at ,baltimore1 ,berlin1 #g ,boston1 #g ,brewster1 #f ,hamburg1 #f ,maidenhead1 #f ,sludge1 as cause of complaints1 #fe ,sodium bisulphite1 #hf ,sodium chloride1 deposits1 #a decomposition of1 #ajf ,sodium hypochlorite1 #aje decomposition of1 #bf effect of ammonia on1 #ba hydrolysis of1 #bf ,sodium thiosulphate1 #hg ,standard of purity1 #cj ,storage tanks1 #ge ,sulphuretted hydrogen1 #cc ,sylvine1 #a ,t ,tannin1 #fg ,tastes1 effect of contact period on nature of1 #fc ,temperature1 effect on absorption of chlorine1 #ce1 #ch bleach deterioration1 #gb dosage1 #cd1 #cf germicidal velocity1 #ch pressure of liquid chlorine1 #if tastes and odours1 #ff ,thermophylic organisms1 #ed ,tolidine1 #hb ,toxic action of chlorine1 #bb1 #bi ,turbidity1 effect on dosage1 #de effect of chlorine on1 #acb ,u ,use of chlorination1 #add ,w ,water mains1 disinfection of1 #h ,well water1 #g ,worcester1 chlorination at1 #aa ,worthing experiments1 #e ,subjects ,related to this ,volume ,for convenience a list of the ,wiley ,special ,subject ,catalogues1 envelope size1 has been printed4 ,these are arranged in groups--each catalogue having a key symbol4 7,see ,special ,subject ,list ,below47 ,to obtain any of these catalogues1 send a postal using the key symbols of the ,catalogues desired4 ,list of ,wiley ,special ,subject ,catalogues #a--;,agriculture4 ,animal ,husbandry4 ,dairying4 ,industrial ,canning and ,preserving4 #b--;,architecture4 ,building4 ,masonry4 #c--;,business ,administration and ,management4 ,law4 ,industrial ,processes3 ,canning and ,preserving2 ,oil and ,gas ,production2 ,paint2 ,printing2 ,sugar ,manufacture2 ,textile4 ,,chemistry #d;,a ,general2 ,analytical1 ,qualitative and ,quantitative2 ,inorganic2 ,organic4 #d;,b ,electro- and ,physical2 ,food and ,water2 ,industrial2 ,medical and ,pharmaceutical2 ,sugar4 ,,civil ,,engineering #e;,a ,unclassified and ,structural ,engineering4 #e;,b ,materials and ,mechanics of ,construction1 including3 ,cement and ,concrete2 ,excavation and ,earthwork2 ,foundations2 ,masonry4 #e;,c ,railroads2 ,surveying4 #e;,d ,dams2 ,hydraulic ,engineering2 ,pumping and ,hydraulics2 ,irrigation ,engineering2 ,river and ,harbor ,engineering2 ,water ,supply4 7,over7 #e;,e ,highways2 ,municipal ,engineering2 ,sanitary ,engineering2 ,water ,supply4 ,forestry4 ,horticulture1 ,botany and ,landscape ,gardening4 #f--;,design4 ,decoration4 ,drawing3 ,general2 ,descriptive ,geometry2 ,kinematics2 ,mechanical4 ,,electrical ,,engineering--,,physics #g--;,general and ,unclassified2 ,batteries2 ,central ,station ,practice2 ,distribution and ,transmission2 ,dynamo-,electro ,machinery2 ,electro-,chemistry and ,metallurgy2 ,measuring ,instruments and ,miscellaneous ,apparatus4 #h--;,astronomy4 ,meteorology4 ,explosives4 ,marine and ,naval ,engineering4 ,military4 ,miscellaneous ,books4 ,,mathematics #i--;,general2 ,algebra2 ,analytic and ,plane ,geometry2 ,calculus2 ,trigonometry2 ,vector ,analysis4 ,,mechanical ,,engineering #aj;,a ,general and ,unclassified2 ,foundry ,practice2 ,shop ,practice4 #aj;,b ,gas ,power and ,internal ,combustion ,engines2 ,heating and ,ventilation2 ,refrigeration4 #aj;,c ,machine ,design and ,mechanism2 ,power ,transmission2 ,steam ,power and ,power ,plants2 ,thermodynamics and ,heat ,power4 #aa--,mechanics4 #ab--,medicine4 ,pharmacy4 ,medical and ,pharmaceutical ,chemistry4 ,sanitary ,science and ,engineering4 ,bacteriology and ,biology4 ,,mining ,,engineering #ac--;,general2 ,assaying2 ,excavation1 ,earthwork1 ,tunneling1 ,etc42 ,explosives2 ,geology2 ,metallurgy2 ,mineralogy2 ,prospecting2 ,ventilation4 ---------------------------------------- ----------------------------- ,additional ,transcriber's ,notes3 99 ,the original symbol in ,table ,,xiv 7a circled 7 has been changed to 4 99 ,some formulas have been spaced out for better readability4 99 ,some minor typographical errors have been corrected 7including indicators for references and missing diacritical marks from ,german words74 99 ,in-line multi-line formulas have been changed to in-line single- line formulas1 if necessary with the addition of brackets4 99 ,inconsistencies in spelling1 hyphenation1 lay-out or formatting have not been corrected1 except in the following cases3 99 ,bassenege1 ,schemmelweiss1 ,langar and ,kanthdack in the name index have been changed to ,bassenge1 ,semmelweiss1 ,langer and ,kanthack as in the text4 99 ,heisse1 ,jordon1 ,tonnetta ,creek and ,horrock's have been changed to ,heise1 ,jordan1 ,tonetta ,creek and ,horrocks's1 respectively1 as elsewhere in the text4 99 ,page #ce3 ,n#a and ,n#b in formula changed to ,n#a and ,n#b as elsewhere4 99 ,page #g3 ,hadallen changed to ,hedallen as elsewhere in the text4 99 ,changes made to the text3 99 ,page #ag3 -- changed to in chemical formula as described in the text4 99 ,page #bf3 ,h4 ,,hco#c changed to ,h4 ,,hco#c'4 99 ,page #bf3 chlor-ions changed to chlorine ions4 99 ,page #ed3 ,gention ,violet changed to ,gentian ,violet4 99 ,page #ajc3 ,footnote marker #aa inserted 7missing in original74 99 ,the author called ,kurpjuivut1 ,kurjuivut and ,kurpjuivat in various places in the text is probably called ,kurpjuweit4 ,the author called ,schumburg and ,schumberg in the text is called ,schumberg4 ,the book contains references to both ,zaleski and ,elmanovitsch and ,valeski and ,elmanovitsch2 ,zaleksi is probably correct4 99 ,other remarks3 99 ,footnote on ,page #aai3 fraction unclear in the original1 presented here as #e-a_/b4 99 ,page #acd3 affluents should probably be effluents4 99 ,in the original work1 there is no ,,table ,,xxii between ,,table ,,xxi and ,,xxiii4 ---------------------------------------- -----------------------------