,,experiments ,,and ,,observations ,,on ,,the ,,following ,,subjects2 #a4 ,on the preparation1 calcination1 and medicinal uses of ,,magnesia ,,alba4 #b4 ,on the ,solvent ,qualities of ,,calcined ,,magnesia4 #c4 ,on the variety in the ,solvent ,powers of ,,quick-,,lime1 when used in different quantities4 #d4 ,on ,various ,,absorbents1 as promoting or retarding putrefaction4 #e4 ,on the comparative ,antiseptic ,powers of ,,vegetable ,,infusions prepared with ,,lime1 c4 #f4 ,on the ,sweetening ,properties of ,,fixed ,,air4 ,,by ,,thomas ,,henry1 ,,apothecary4 ,utut tamen se res habeat1 ego bona saltem fide tradam qu hactenus rescivi omnia4 ,,sydenham4 ,,london3 ,printed for ,,joseph ,,johnson1 ,no4 #gb1 ,st4 ,paul's ,church-,yard4 ,,mdcclxxiii4 ,,to ,,thomas ,,percival1 ,m4,d4 ,f4,r4,s4 ,s4,a4 ,,dear ,,sir1 ,when ,i reflect how much the friendship with which you have favoured me has contributed to my happiness2 that from you has been imbibed a considerable share of the small taste ,i possess for experimental inquiries2 and that to your skilful and affectionate treatment ,i am greatly indebted even for the health ,i enjoy2 it is impossible to hesitate a moment in the choice of a patron3 gratitude and esteem direct me to inscribe this ,treatise to you1 and ,i chearfully obey their dictates4 ,if to these any additional motive had been wanting1 ,i should have received it from your having been an evidence to the result of many of the experiments related in the following pages4 ,that your own health may long enable you to continue exemplarily useful to your friends and to the public1 is the sincere and ardent wish of1 ,,dear ,,sir1 ,your truly affectionate and very humble ,servant1 ,,thomas ,,henry4 ,,manchester1 #ahth ,jan4 #aggc4 ,,the ,,preface4 ,a right composition of the several articles used in medicine1 is of so much importance to the practice of it1 that every attempt to improve or ascertain the method of preparing them1 cannot fail of a candid reception from the public4 ,though great advancement has been made within these few years in chemical pharmacy1 by the labours of the very ingenious ,dr4 ,lewis1 and some other writers on chemistry and the materia medica1 there is still a wide field left for improvement4 ,it is to be wished that ,apothecaries1 to whose province researches of this kind more peculiarly belong1 and many of whom are well qualified by a liberal education to pursue them with advantage1 would give their attention to these material interests of the art3 for while the several professors of medicine and of surgery1 are most laudably and assiduously employed in adding to the enlargement of these sciences1 why should the sons of pharmacy remain supinely inactive1 and leave every thing towards the improvement of their profession to be performed by the members of the elder branch of physic1 instead of contributing their share to its support8 as if tacitly acknowledging themselves unequal to the task1 and thereby incurring the too general1 though unmerited1 imputation of want of knowledge and skill in their department4 ,the first part of the ensuing ,treatise1 which relates an improved method of preparing ,magnesia ,alba1 has been communicated to the ,college of ,physicians2 and that learned body have done the author the honour to insert it in the second volume of their ,,transactions4 ,it is here reprinted as a proper introduction to the subsequent pages4 ,the calcination of ,magnesia is not a new processa2 but1 as in this state it is a medicine not much introduced into practice1 perhaps a few hints may be suggested1 in regard to its medicinal and pharmaceutical properties1 which are not generally known2 and it is hoped that some useful information may be communicated relative to the various action of absorbent medicines on the bile4 a ,the ,german and ,italian chemists formerly prepared ,magnesia by evaporating the mother of nitre1 and then calcining the residuum2 but1 ,hoffman having discovered the method of precipitating it from the bittern remaining after the crystallization of sea salt1 the calcination was disused1 as tedious and unnecessary4 ,in the succeeding chapters1 it is attempted to determine how far1 and in what proportion1 lime promotes the solution of vegetable astringents1 and other drugs in water2 and whether the action of antiseptic medicines1 thus dissolved1 be in any degree impaired or increased by this mode of obtaining tinctures from them4 ,in endeavouring to contribute to the determination of the question1 whether fixed air has the power of restoring sweetness to putrid substances1 the ,author may at first sight appear to have transgressed his proper limits2 but1 as fixed air1 if possessed of this property1 is likely to be a valuable acquisition to the materia medica1 he flatters himself he shall incur no censure by the attempt4 ,,the ,,contents4 ,,chap4 ,i4 ,page ,an ,account of an improved ,method of preparing ,magnesia ,alba4 #a ,,chap4 ,,ii4 ,miscellaneous ,observations4 #ab ,,chap4 ,,iii4 ,on the ,medicinal ,properties of ,magnesia ,alba4 #be ,,chap4 ,,iv4 ,on the ,calcination of ,magnesia ,alba4 #ci ,,chap4 ,v4 ,on the ,medicinal ,virtues of ,calcined ,magnesia4 #dh ,,chap4 ,,vi4 ,on the ,action of various ,absorbents1 as promoting or retarding putrefaction4 #eh ,,chap4 ,,vii4 ,on the ,solvent ,qualities of ,calcined ,magnesia4 #hj ,,chap4 ,,viii4 ,on the various ,solvent ,powers of ,quick ,lime in different ,quantities4 #hh ,,chap4 ,,ix4 ,on the comparative ,antiseptic ,powers of ,vegetable ,infusions prepared with ,lime1 c4 #aje ,,chap4 ,x4 ,on the ,sweetening ,properties of ,fixed ,air4 #aad ,,chap4 ,,xi4 ,a ,review of the general ,conclusions deducible from the foregoing ,observations and ,experiments4 #ace ,,an ,,appendix #adc ,,errata4 ,page #h1 line #ad1 after quantity read of water4 ,page #aj1 line #ah1 for interrupt read intercept4 ,page #ac1 line #a1 read is there said4 ,page #af1 line #a1 read the other absorbents4 ,page #bi1 note1 line #d from the bottom1 for albuminis read aluminis4 ,page #ca1 line #d1 for patients read parents4 ,page #hc1 line #i1 after elegant read green4 ,page #abf1 line #c1 erase the comma after smell4 ,page #abg1 line #c1 place a comma instead of the semicolon4 ,,chap4 ,i4 ,,an ,,account ,,of ,,an ,,improved ,,method ,,of ,,preparing ,,magnesia ,,alba4 ,although ,,magnesia ,,alba is a medicine which has been in general use for many years1 yet the proper mode of making it is very little known4 ,our pharmacopia affords us no information about it2 and the formula which is given by the ,edinburgh ,college1 as well as that with which the ingenious ,doctor ,blackb has favoured us1 is deficient in several circumstances4 ,hence the preparation of pure ,magnesia has been confined to very few persons1 who have preferred the emolument they have received by keeping their method secret1 to the more diffusive utility of which a publication of it would have been productive4c ,i therefore beg leave to lay before the public a process for the preparation of ,magnesia1 by which it will be in the power of every ,apothecary to make it himself1 in all respects equal to that which is sold by those who conceal their method4 b ,essays and ,observations ,physical and ,literary1 ,vol4 ,,ii4 c ,mr4 ,glass1 a few years since1 published an ,essay on ,magnesia ,alba1 in which all the information he affords us relative to the preparation is what we knew before1 viz4 that it is prepared from ,epsom salts and pot ashes2 and has related a number of difficulties which occur in the process1 at the same time carefully1 ,i had almost said meanly1 avoiding giving the least instruction which might teach us how to shun them1 though he has given a long detail of the many tragical consequences which may attend the use of ,magnesia prepared under such disadvantages4 ,i am the more strongly induced to make this communication1 because the ,magnesia which is generally to be found in the shops1 is either extremely coarse and ill prepared1 or1 which is still worse1 sophisticated with calcareous substances1 differing greatly from true ,magnesia4 ,i have been assured by some ,physicians1 that they have met with it mixed with chalk1 and even with lime1 and ,i have sometimes seen it so adulterated3 a fraud of very dangerous tendency1 as this powder is so frequently administered to very young infants1 and to adults of tender bowels and costive habits4 ,this medicine was originally prepared abroad1 from the liquor called the mother of nitre1 which is composed of a light earth united with an acid2 and these being separated1 either by a strong fire1 or by the addition of an alkali1 the powder was washed in water1 and obtained the name of ,magnesia ,alba4 ,hoffman afterwards prepared it from the bittern remaining after the crystallization of sea salt1 which he found to be similar to the mother of nitre4 ,and the factitious ,epsom salt being prepared from this bittern1 and evidently composed of ,magnesia and the vitriolic acid1 ,dr4 ,black1 who has favoured the world with a number of very valuable experiments on this subject1 made use of this salt with success for the same purpose4 ,happening some years ago to live in the neighbourhood of a gentleman who has long been celebrated as the preparer of the most genuine ,magnesia1 and never having been able myself to make ,magnesia comparable to his1 by the commonly known methods1 ,i was desirous of gaining some intelligence as to his process1 and was at last so fortunate as to obtain some useful hints4 ,i availed myself of these1 and after repeated trials1 produced ,magnesia equally pure1 white1 tasteless1 light and impalpable with that of ,mr4 ,glass2 nay sometimes that of my own preparing has been superiour to his1 and in one respect has generally the advantage of it1 namely1 that mine is not so stiff when dried1 and may be reduced to the finest powder by simple pressure2 whereas his requires some degree of trituration to break the lumps effectually2 which ,i imagine may be owing to his pursuing ,dr4 ,black's method of drying it1 by straining and pressing out the water through a cloth4 ,the following is the manner of preparing it1 which ,i have found successful4 ,dissolve any quantity of sal catharticus amarus1 commonly called ,epsom salts1 in its own weight of water2 filter the liquor1 and add to it by degrees a filtrated solution of pearl ashes in an equal quantity of water1 stirring them gently until the mixed liquors have acquired the appearance of a complete coagulum3 then cease adding any more of the alkaline lixivium2 and1 having diluted the precipitate1 and mixed it intimately with a small quantity of hot water1 immediately throw the mixture into a large vessel of boiling water4 ,keep it boiling for a quarter of an hour1 then take it out1 and put it into glazed earthen vessels4 ,as soon as the powder has subsided1 and before the water be quite cold1 pour it off1 and add a fresh quantity of boiling water3 repeat these ablutions with several parcels of hot water1 till the liquor has entirely lost its saline taste4 ,then let it be so agitated as to suspend the finer parts of the powder2 in which state decant it into other vessels1 and having separated the water from the ,magnesia by inclination1 put it on large chalk stones1 till a considerable part of the humidity be absorbed4 ,then wrap it up in sheets of white paper1 and dry it before the fire4 ,pour hot water on the remaining powder1 stir it1 decant it in its turbid state1 and separate the ,magnesia from the water as before4 ,by these means1 the whole1 or most of it1 will be reduced to an equal degree of fineness4 ,the separation of the ,magnesia will be promoted by heating the saline lixivia before they are mixed2 and the larger the quantity of water into which the precipitated powder is cast1 the more speedily and perfectly will the vitriolated tartar1 which is formed by the alkali of the sal catharticus1 be washed off4 ,dr4 ,black directs that three or four times the quantity of water1 to that of the solutions1 should be added2 but this ,i have found greatly insufficient4 ,the neutral salt should be washed off as quickly as possible2 otherwise1 as he justly observes1 by allowing the mixture to stand for some time1 the powder concretes into minute grains1 which when viewed with a microscope1 appear to be assemblages of needles diverging from a point4 ,these concretions cannot be redissolved by any washing1 however long continued4 ,his intention1 in boiling the mixture1 is much better answered1 by adding it to the water when in a state of ebullition2 and once boiling in this manner is more effectual than a dozen washings in hot water4 ,much depends on the purity of the water used in the process4 ,if it be hard pump water1 the selenites with which it is impregnated will be decompounded1 and the calcareous earth be deposited1 after boiling2 which mixing with the ,magnesia will render it impure1 gritty and discoloured4 ,rain water collected free from impurities1 or clear river water1 are most eligible2 but if the situation of the operator does not permit him to procure these in a proper state1 he should either use distilled water1 which has been kept till the empyreuma is gone off1 or at least such pump water as is free from any calcareous or saline impregnation4 ,when poured on the ,magnesia1 it should be strained through a thick linen cloth1 so as to intercept any accidental impurities which it may acquire in heating4 ,the drying should be performed with expedition4 ,to this end1 the chalk stones should be exposed to a moderate degree of heat2 and when they have been employed two or three times1 should be dried before a fresh quantity of the ,magnesia is put on them4 ,cleanliness should be particularly attended to through the whole process2 and the vessels ought to be carefully covered1 that no dust may enter4 ,we may safely make use of a large copper brewing-pan1 to boil the ,magnesia in2 for as the acid is perfectly neutralized1 there can be no danger of its quitting the alkali1 to which it has a greater affinity than to the metal2 and copper does not readily dissolve1 even in acids1 when boiling hot2 nor have ,i ever observed the least corrosion1 though ,i have frequently used such vessels for this purpose4 ,,chap4 ,,ii4 ,,miscellaneous ,,observations4 ,since the drawing up of the paper which has been the subject of the last chapter1 some observations have occurred1 which are either so immediately connected with1 or at least deduced from it1 that it may not perhaps seem inexpedient to introduce them in this place4 ,i was very much surprised to observe1 in the ,lectures lately published1 as delivered by the very learned and ingenious ,dr4 ,cullen1 that ,magnesia is there said to be no more purgative than any other absorbent earth4 ,the sentence is this2 7speaking of other absorbents7 ,magnesia alba should have been added to this set4 ,it has had a considerable reputation as an absorbent1 and when neutralized1 as a purgative2 but ,i find it is not more absorbent than any of the rest1 nor more purgative in less quantity1 as chalk or crab's eyes given in the same quantity1 viz4 dramij1 will have the same effect4 ,therefore it may be neglected4 ,surely this must have been an error of the person who wrote down the lectures1 and have escaped the notice of the ingenious editors2 who1 from their skill in chemistry1 must know that pure ,magnesia differs from every calcareous or testaceous earth with which we are hitherto acquainted4 ,these earths are nearly insoluble in the vitriolic acid1 and what part does unite with it1 forms a selenitical salt1 the most difficult of solution of all others1 and of an astringent nature3 whereas the ,magnesiad united with the same acid1 produces what is commonly called ,epsom salt1 easy of solution1 and purgative to the bowels4 ,the former1 with the nitrous acid constitutes a calcareous nitre1 incapable of crystallization2 with the marine acid a calcareous muriatic salt2 and when dissolved in vinegar1 the mixture spontaneously dries up into a friable sub-astringent salt3 whereas ,magnesia1 with all these acids1 forms purging salts2 that with the nitrous acid1 yellow1 capable of being reduced into crystals retaining their form in a dry air1 but melting in a moist one3 with the muriatic acid1 a salt is produced which does not crystallize1 and easily melts when exposed to the air3 with distilled vinegar1 a saline uncrystallizable mass is formed1 resembling glue both in colour and consistence while warm1 but becoming brittle when cold4 ,dr4 ,black says1 that two drachms of this salt purged a middle aged man four times2 and half an ounce of the same gave a woman of a strong constitution no less than ten stools4e d ,essays ,physical and ,literary1 ,vol4 ,,ii4 p4 #afd4 e ,ibid4 p4 #fd4 ,besides1 where an acid prevails1 much smaller doses than two drachms of ,magnesia prove purgative2 and it seldom happens that even that dose of the other absorbentsf will produce the same effect4 ,nor am ,i singular in my opinion1 when ,i declare my doubt whether ,magnesia be not of itself in some degree purgative1 independent of its junction with any acid whatsoever4 ,it appears to be an earth sui generis4 ,that of alum resembles it in some respects1 yet differs from it essentially1 when combined with the vitriolic acid3 the alum is strongly astringent and antiseptic1 the ,epsom salt purgative and septic4 f ,hoffman1 having attributed the purgative quality of ,magnesia to its forming a bitter cathartic salt with the acid it meets with in the stomach and bowels1 adds1 ,at vero in contrarium quoddam dubium contra hanc sententiam moveri posse intelligo1 quum nempe alia terrea1 qu prompte solvent et absorbent inhrescens primis viis acidum1 neutiquam effectum laxantem exserant4 ,sed his regerere licet1 quod interdum a pulveribus absorbentibus vel bezoardicis utique alvus fluidior fiat1 si multum acidi primam regionem incolet3 vis tamen eorum purgandi non tanta est1 quanta magnesi1 quia solutiones illorum cum acidis liquoribus fact non tam eminente salino acri1 sed moderate salso sapore imbut sunt1 quam quidem ea1 qu ex magnesia et acidis liquoribus conficitur4 ,atque adeo ex eo apparet1 prter alcali terreum aliud adhuc esse in magnesia principium1 quod ad mixturam acidi in materiem stimulantem et purgantem transeat4 ,hoffman4 ,animadversiones et experimenta circa ,magnesiam1 c4 ,op4 ,tom4 #d4 p4 #dhj4 ,i have very lately seen a paper signed by ,doctor ,cadogan and dated in the year #agfg1 in which he complains grievously of the advertisers of ,magnesia1 making use of his name without his consent1 and has published the process for making his ,magnesia4 ,the doctor's intent in this was doubtless benevolent1 but his manner of preparing this powder is unnecessarily expensive and wasteful4 ,he directs only one pound of lixivium tartari to five pounds of sal catharticus amarus1 which is greatly insufficient to precipitate all the ,magnesia4 ,and he insists strongly on the superiority of the lixivium prepared from salt of tartar1 to that made of potashes1 as if the chemical effects of one1 were different from the other4 ,but1 says the ,doctor1 potashes render the ,magnesia bitter4 ,surely the vitriolated tartar produced by a union of one vegetable fixed alkali with the vitriolic acid1 is equally soluble in water with that prepared with any other1 and if so1 will be as easily washed off from the ,magnesia4 ,but behold a champion steps forth1 and at one blow levels to the ground the whole tribe of ,magnesia makers1 who have procured it from the factitious ,epsom salts4 ,i confess ,i have not had the happiness to peruse this ingenious gentleman's pamphlet on the subject1 but ,i have formed a very extraordinary opinion of his candour1 modesty1 and knowledge1 from the very curious paper which he distributes with his ,magnesia4 ,notwithstanding ,doctor ,black1 and since him ,mr4 ,glass and several others1 have procured pure ,magnesia from the factitious ,epsom salts1 ,mr4 ,dale ,ingram1 assures us1 that he has made an improvement1 which is by the learned esteemed one of the greatest acquisitions to the materia medica4 ,and wherein does this mighty discovery consist8 even that ,magnesia prepared from the waters of ,epsom1 is superiour to that prepared from the bitter purging salt2 and he assures us that the ,magnesia sold by him is so prepared4 ,to the first assertion ,i shall only reply1 that every person at all conversant in chemistry knows that ,magnesia earth is the same1 from whatever substance it can be separated in a pure state2 that the factitious ,epsom salt yields it in as great a degree of purity as the salt of the ,epsom water1 and that ,dr4 ,alston assures us1 the artificial salt by various and repeated experiments1 made in ,france as well as in ,britain1 is demonstrated to be every way as good as1 yea to be the very same with1 the genuine made of the ,epsom waters4g g ,alston's ,materia ,medica1 ,vol4 ,i4 p4 #afd4 ,as to the other declaration1 it will be sufficient to observe that one gallon of ,epsom water contains only seven drachms of salt in a dry season1 and hardly six drachms in a wet one2h and that for this salt to precipitate its ,magnesia properly1 it is necessary it should be diluted with little more than its own weight of water4i ,six drachms of salt will yield two drachms of ,magnesia4 ,so that to procure a pound of this powder ,mr4 ,ingram must evaporate above sixty gallons of the water1 to between five and six pints1 before he begins the precipitation4 ,sure never did empiricism appear so thinly disguised6 h ,ibid4 i ,essays ,physical and ,literary1 p4 #afc4 ,in the preceding chapter1 the necessity of using water free from any calcareous impregnation has been particularly insisted on1 and ,i have1 on another occasion1j observed that great attention should be given to the purity of the water used in the making of all the saline preparations2 and ,i may add in almost all the operations of pharmacy4 ,dr4 ,percival1 in his ingenious experiments on water1 found a quart of the ,manchester pump water to contain upwards of sixty grains of adventitious matter4k ,suppose therefore1 for instance1 that in making the extract from a pound of peruvian bark1 it be boiled only six times in the quantity of water directed by the ,london ,dispensatory1 nine gallons will be consumed in the process2 which is a very moderate allowance1 six coctions not being sufficient to extract all the virtues of that drug4 ,dr4 ,percival boiled half an ounce of bark twenty five times1 in so many different pints of water1 the last of which had some impregnation1 and the residuum gave a deep colour1 and considerable bitterness to rectified spirit of wine4 ,if we likewise suppose only one half of the foreign contents of such water to be left by evaporation1 then the quantity of calcareous and saline matter1 undesignedly mixed with the extract1 will be two ounces and two drachms1 or nearly equal to the quantity of extract procured from a pound of bark by pure water4 ,thus this important medicine becomes grossly adulterated1 without any such intention in the operator2 and ,i know it is the common practice to use pump water in making it4 j ,vide ,percival's ,essays1 #b;d4 ,edit4 p4 #cba4 k ,ibid4 p4 #hg4 ,i have particularly selected the ,peruvian bark1 as requiring a very large quantity of water to extract the whole which it is capable of yielding2 but the proportion of water which ,i have here allowed1 will not be too great in obtaining extracts from most vegetable substances2 and how greatly not only the quantity1 but the quality of the medicine must be affected by the admixture of such a weight of insoluble calcareous earth1 is so obvious1 that it is needless to expatiate on it4 ,,chap4 ,,iii4 ,,on ,,the ,,medicinal ,,properties ,,of ,,magnesia ,,alba4 ,the medicinal uses to which ,magnesia has hitherto been applied are in general so well known1 that it will be necessary only to give a short summary of the cases in which it is beneficial1 for the information of young practitioners1 and of those of my readers who may not be acquainted with medical subjects1 this medicine being frequently administered without the advice of a physician4 ,if it should appear in the subsequent part of this treatise that ,magnesia is possessed of any properties hitherto unsuspected in it1 the sagacious reader will in a great measure be left to draw his own practical inferences therefrom4 ,,magnesia ,,alba is a powerful absorbent1 and is given with great success in disorders of the stomach and bowels arising from acidity4 ,this preparation had been introduced into the materia medica abroad several years before it attracted the attention of our countrymen4 ,the celebrated ,hoffman having strongly recommended it to the medical world1 some ,english practitioners began to prescribe it1 and ,dr4 ,cadogan bestowing high encomiums on it1 in his treatise on the nursing and management of children1 it soon made its way into general practice1 and supplied the place of the testaceous powders and chalk1 which before this period were the medicines usually given to correct acidities in the prim vi4 ,the acquisition of this medicine was of the more importance1 on account of its entire and easy solution in acids1 and of the purgative quality which it possesses2 whereas the common absorbents are apt to form concretions1 and to induce costiveness2 strong objections to their free exhibition1 as these properties render them peculiarly unfit for the bowels of tender infants who are particularly liable to diseases of this class4 ,this tendency to acidity generally attends children during the first months and the time of dentition1 and discovers itself when too redundant by the green stools1 sour vomitings1 gripes and purgings which it occasions3 and as the nerves of children are extremely irritable1 spasmodic affections are often the consequence of this acrid stimulus being retained in their bowels4 ,in these cases ,magnesia may be administered in doses from five to twenty or thirty grains1 according to the age of the infant2 and in proportion as it is intended to act1 either as an alterative1 or as an easy purgative4 ,it has been a common practice to give ,magnesia to children as a preventive1 and to mix it for this purpose with their food1 in order to correct that disposition which milk and the farinaceous aliments have to turn sour4 ,this however should be done with caution1 for it is only the excess of acidity which is prejudicial to infants1l some degree of it is necessary2 and should we too officiously and entirely destroy1 what we ought only to restrain within due bounds1 we may create disorders of an opposite nature to those we have endeavoured to prevent1 and instead of an acid1 produce an alkalescent disposition in the first passages4 ,indeed ,i fear that diseases have been more frequently created than obviated by the use of preventive medicines1 and they should only be allowed in cases where the approach to disease is manifest4 ,but when a child is in a healthy state1 the best means to preserve him from a superabundant acidity1 is to pay due attention to the regulation of his diet1 to give him proper exercise1 not to confine him too much in the foul air of hot unventilated rooms1 to wash his whole body every day in cold water1 and to rub him very well night and morning with a dry flannel1 taking care that his stomach be not too full at the time when this friction is performed4 l ,hactenus monstravimus1 sicut cordis1 musculorumque vires debiles erant1 ita et solidorum quoque statum necessario imbecillem fuisse1 et succos tenues1 dilutosque2 ut natura ampliationem vasculorum facilius efficeret1 et incrementum animale minori cum molesti perageret4 ,sed ne status iste tonusque partium debilis laxusque ultra modum procederet 7quod spe accidit1 morbosque excitare solet7 acidum quoddam juvenilium animalium stomachis datum est1 quod quamvis aluminis instar1 lac coagulat1 atque ob eam causam aliquando morbum procreat1 tamen fibrarum tonum astringet confirmatque1 et putredinem omnem alkalinam1 a qua alioquin periculum esset1 reprimit4 ,quod quidem videri est1 vel in coagulo stomachi vitulini1 vel in aliis animalibus3 sed istud tamen acidum1 quod infantibus tarn idoneum est1 redundat fortasse nonnumquam1 et vel per testaceas pulveres1 vel per medicamenta antiacida1 ut supra dixi1 corrigi debet4 ,russelli ,o,economia ,natur1 p4 #ef4 ,nor would ,i advise parents to rely with too much security on the virtues of this medicine1 where the disorders of their children are complicated1 or obstinate4 ,the advice of the sagacious and distinguishing practitioner will then be necessary to direct what method of treatment is to be pursued4 ,nor can ,i here avoid lamenting that the management of children when diseased1 is so often in the hands of nurses and ignorant women1 from an absurd notion that their diseases are not proper subjects of medical investigation2 when in truth1 there are none which require a clearer judgement1 a quicker penetration1 or a greater share of medical knowledge in the prescriber4 ,during the period between dentition and puberty1 the diseases attendant on a lax fibre still continue1 though not so predominantly as in the former stage2 yet acescency is the manifest cause1 or at least the concomitant of many of the complaints to which children are at this time liable4 ,to this they are disposed1 notwithstanding the change in their diet to a more alkalescent kind1 by the great quantities of fruit1 frequently crude and unripe1 cakes1 and other sweet and greasy food with which they are too often indulged4 ,by these errors their bowels are overcharged1 their digestion impaired1 and the aliment remaining too long in the stomach becomes sour1 and occasions vomitings1 head achs1 and other complaints which are often thought to proceed from worms1 and indeed are frequently attended with that disorder2 as the crudities thus generated in the bowels serve as a nidus for these destructive vermin4 ,here likewise ,magnesia may be of considerable advantage as an alkaline purgative1 neutralizing the offending acid1 and at the same time promoting its discharge by stool4 ,but if the stomach be overloaded with mucus or undigested aliment1 a gentle vomit ought to precede the exhibition of the ,magnesia4 ,and even in a more advanced stage of life1 persons of weak habits1 and who lead sedentary lives1 are often afflicted with indigestion1 sour eructations1 heart-burn1 vomitings1 and costiveness4 ,these disorders very frequently attend women during their state of pregnancy1 and are sometimes almost instantly removed by the use of ,magnesia4 ,dr4 ,watsonm has published the case of a pregnant woman1 who was afflicted with such severe vomitings as to bring on convulsions1 hiccoughing1 and violent pain at her stomach4 ,what she brought up was acid1 and so very acrimonious1 as to inflame and excoriate her mouth and throat2 and the great uneasiness she felt at her stomach upon swallowing any liquor that had the least degree of acrimony1 or was more than lukewarm1 made it probable that the internal surface of the stomach was affected in the same manner4 ,in this desperate situation1 after a variety of remedies had been tried in vain1 the stomach was washed with unsalted mutton broth1 till the liquor was discharged without any acid taste4 ,her pain was by this means abated1 but in about two hours was apparently returning with the same violence as before4 ,this ingenious ,physician then directed a drachm of ,magnesia to be given in mutton broth1 and to be repeated as often as her pain returned1 without any regard to the quantity the whole might amount to1 supposing her pain to continue severe4 ,the first dose relieved her1 and in three days she took three ounces of ,magnesia2 and in the next three days1 two ounces more1 by which time all her symptoms were removed4 ,it is remarkable in this case that a hypercatharsis was not the consequence of taking so large a quantity of ,magnesia1 where there was so much acid to neutralize it4 m ,medical ,observations and ,inquiries1 ,vol4 ,,iii4 p4 #cce4 ,in bilious habits1 where there is generally a disposition in the stomach contrary to acidity1 ,magnesia is usually esteemed to be improper1 taken alone3 but ,i am dubious whether this opinion is well founded1 and many reasons for these doubts may be deduced from the experiments hereafter to be recited4 ,however1 where putrid bile is to be corrected and discharged1 by stool1 very good purposes may1 perhaps1 be answered by taking the ,magnesia1 joined with a sufficient quantity of acid to neutralize it1 while in a state of effervescence2 or by swallowing the ,magnesia and the acid1 one immediately after the other1 so as to produce the fermentation in the stomach3 for thus the fixed air with which the ,magnesia so greatly abounds1 being let loose1 may powerfully correct the tendency to putridity in the contents of the prim vi1 and at the same time evacuate them downwards4 ,how far ,magnesia may be of service in diseases of the skin ,i do not take upon me to determine4 ,several authors have attributed cutaneous eruptions1 and indeed the ancient chemists ascribed almost all disorders1 to the presence of an acid in the blood2 whilst others absolutely deny that an acid can be admitted into the lacteals1 or1 if admitted1 exist in the blood in a state of acidity4 ,in these cases however1 if an acid acrimony abounds in the stomach and bowels1 with a costive habit1 and pale complexion1 ,magnesia will be a useful corrector1 and entering into the circulation in the form of a mild neutral salt1 may act as an excellent alterative1n proving both diaphoretic and diuretic4 ,having thus given a cursory detail of the medicinal properties of ,magnesia1 in its natural state1 ,i shall now proceed to consider it in a state of calcination3 but before any description of its uses in medicine be given1 it may be proper to take a view of the changes which are produced in the nature of it by this operation4 n ,neque enim tantum absorbentem et catharticam1 si acidum prim in regione stabulatur1 virtutem exserit2 verum etiam si in remissiore dosi1 ad grana xv4 vel xx4 usurpatur1 diaphoreticum et diureticum effectum sequi1 non semel observavimus4 ,hoffman4 circa ,magnesiam4 ,oper4 ,tom4 #d4 p4 #dha4 ,,chap4 ,,iv4 ,,on ,,the ,,calcination ,,of ,,magnesia ,,alba4 ,the free spirit of inquiry1 and taste for experimental researches which have of late so happily prevailed1 have given rise to several very important discoveries in the course of the last half century2 among which1 those of the properties of the electrical fluid1 and of fixed air1 hold a principal rank4 ,that excellent philosopher and experimentalist1 the late ,doctor ,hales1 first proved that most bodies contain1 as one of their component principles1 a quantity of air1 differing from that of the common atmosphere in several of its properties4 ,the proportion of this element varies in different substances1 and in some constitutes nearly one half of their weight4 ,all calcareous earths1 the testaceous powders1 ,magnesia and alkaline salts contain it abundantly1 and have the strongest affinity with it of any bodies1 except metals4 ,from all these it is discharged by an acid1 and the stronger the acid is1 the more sudden and plentiful is the discharge of this vapour1 which is of the same nature as that emitted by fermenting liquors4 ,though it may be inspired in small quantities with impunity1 and1 as appears from some late observations1 even with advantage in some cases1o yet it is a known fact that animals expire sooner in a receiver filled with fixed air1 than in vacuo4 ,lastly1 it is said to have the remarkable property of rendering putrid substances sweet4 o ,the reader is referred for further information on this subject1 to an excellent ,treatise on the ,management of ,pregnant and ,lying-in ,women1 lately published by my worthy and ingenious friend ,mr4 ,white2 to a volume of ,experiments and ,observations1 by ,dr4 ,percival1 which is now in the press2 and to some very curious papers on factitious air1 which have lately been communicated to the ,royal ,society1 by ,dr4 ,priestley4 ,in the precipitation of ,magnesia1 the acid of the ,epsom salt uniting with the alkali which is added to the solution1 expels the fixed air which the latter contains2 but the vapour instead of being dissipated as in the common effervescing mixtures of acids and alkalis1 is quietly and immediately absorbed by the ,magnesia earth1 to which it has a strong affinity2 and thus a double elective attraction takes place4 ,the very large proportion of this element contained in ,magnesia ,alba has given ,dr4 ,black an opportunity of throwing much light on this hitherto obscure subject2 and that excellent chemist has drawn such inferences from the result of his experiments on ,magnesia1 ,quick-lime1 and other alkaline substances1 as are of the utmost importance to chemistry4 ,as this treatise may fall into the hands of several who may not have an opportunity of perusing the valuable ,essays in which these experiments are contained1 ,i shall take the liberty to make a short extract from them1 in order to elucidate the subject of the subsequent pages4 ,the first object of ,dr4 ,black's enquiry was1 whether ,magnesia could be reduced to ,quick-lime4 ,to this purpose1 he calcined an ounce of ,magnesia in a strong fire4 ,when taken out of the crucible and weighed1 it had lost seven twelfths of its weight4 ,combined with different acids1 it formed salts of a similar nature to those constituted by the same acids with the uncalcined powder2 but dissolved in them without the least degree of effervescence4 ,it slowly precipitated the corrosive sublimate of mercury1 in the form of a black powder2 whereas before calcination a dark red precipitate was formed from the same substance4 ,mixed with a warm solution of salt ammoniac1 it separated the volatile alkali from the acid2 but it made no separation of an acid from a calcareous earth1 nor did it induce any change upon lime-water2 whereas in an uncalcined state1 it rendered quick-lime mild4 ,lastly1 being digested for some hours with water1 it produced not the least alteration in the water4p p ,in making this experiment some time since1 ,i imagined that ,doctor ,black had been mistaken in this point1 and that some impurity in the water had prevented the success of his process1 for ,i found the water impregnated1 as ,i supposed1 with the ,magnesia4 ,flushed with my supposed success1 ,i proceeded to make experiments on the lithontriptic powers of this water1 which ,i found to be very considerable1 acting more efficaciously on the human calculus1 than either oyster-shell lime water1 or a dilute solution of soap ley4 ,i communicated this interesting intelligence to some of my medical friends2 but on repeating my experiment several times with different parcels of ,magnesia1 that the truth of the fact might be absolutely ascertained1 ,i at last was convinced1 to my no small mortification1 that what ,i had too sanguinely flattered myself to be a discovery likely to be highly serviceable to mankind1 was founded on error2 and that the properties communicated to the water proceeded from some calcareous matter which the ,magnesia had received by being washed with impure water4 ,i mention this as a caution to every young experimentalist1 to be extremely careful in drawing conclusions4 ,however1 as something may be learned1 even from an unsuccessful experiment1 it proves that a very small quantity of lime is sufficient to impregnate a large quantity of water2 for ,i used the calcined ,magnesia1 in the same proportion as lime is directed for making lime-water1 so that very little of it could be quick-lime4 ,and as oyster-shell lime water is a superiour solvent of the calculus to the water prepared with stone lime1 is there not some reason to think that the calcareous earth1 which has been dissolved in hard water1 may1 when calcined1 be a more powerful lithontriptic1 than either of the others8 ,if any inference can be drawn from it1 which may in the least promote the interests of mankind1 ,i shall be sufficiently recompensed for the humiliating circumstance of recounting an erroneous experiment4 ,in pursuing his inquiries1 he found that a very small portion of what had been lost in the calcination was water1 and that the other part was fixed air1 by the loss of which the ,magnesia was deprived of its power of effervescing with acids4 ,and from hence the ,doctor concluded1 that the change made in calcareous substances and in ,magnesia by calcination1 was chiefly produced by depriving them of this air2 and that this volatile ,proteus may be conveyed from one body containing it to another body with which it has a greater affinity4 ,thus lime being deprived of its air by calcination1 and having a stronger affinity with it than alkaline salts have1 being mixed with a lixivium of these salts1 absorbs all the air from them1 deprives them of their property of effervescing with acids1 and renders them more acrid1 at the same time that the lime becomes mild1 and incapable of impregnating water1 but recovers its power of fermenting when mixed with an acid4 ,,chap4 ,v4 ,,on ,,the ,,medicinal ,,virtues ,,of ,,calcined ,,magnesia4 ,frequent objections have been made to the use of ,magnesia ,alba1 on account of the great quantity of air which enters into its composition4 ,whenever it meets with an acid in the stomach they immediately unite2 but in forming this union1 all the air contained in the ,magnesia is discharged with a great degree of effervescence1 and recovering its elasticity sometimes occasions very uneasy sensations in weak bowels1q inflating and distending them overmuch1 inducing griping pains1 and above all a sense of debility or sinking1 which is not easily described4 q ,neque tamen prterire possumus1 id incommodi nos quandoque ab hoc ,magnesi pulvere deprehendisse1 quod flatulentias et morsicationes in imo ventri reliquerit1 si videlicet frequentius in usum trahatur1 primaque regio progignendis corrosivis succis1 ut in hypochondriacis fieri solet1 exposita sit4 ,hoffman4 ,oper4 ,tom4 #d4 p4 #cha4 ,my much respected friend ,doctor ,percival1 who had often complained of these disagreeable effects from the use of ,magnesia1 suggested to me the idea of depriving it of its fixed air by calcination1 having been informed that they would be obviated by this method4 ,doctor ,black had indeed proved the practicability of the process1 but he does not appear to have made trial of the calcined ,magnesia as a medicine4 ,in consequence of the above hint ,i calcined some ,magnesia1 and was afterwards insensibly led to make further experiments1 the event of which1 ,i hope1 will be deemed of sufficient importance to apologize for my communicating them to the public4 ,,experiment ,i4 ,eight ounces of pure ,magnesia ,alba were calcined with a strong fire in an air furnace4 ,three hours calcination were necessary to discharge the whole of the air from the ,magnesia4 ,when removed from the fire1 it had lost four ounces and three drachms of its original weight1 and produced no effervescence with acids2 it had not acquired any degree of acrimony to the taste1 and when thirty grains of it were diluted with a few spoonfuls of water and swallowed1 it occasioned no uneasy sensation in my stomach1 nor sense of heat in my throat2 proved nearly as aperient as a double quantity of uncalcined ,magnesia1 and operated without the least griping4 ,it was remarkable that calcination had not reduced the powder in bulk1 in proportion to the diminution of its weight4 ,by the process of this experiment1 ,magnesia ,alba is not only divested of the disagreeable qualities which have been alluded to1 but acquires new properties which render it likely to answer some very important practical purposes4 ,doctor ,macbride1 who has with the greatest ingenuity and accuracy1 prosecuted the investigation of the nature of fixed air1 discovered1 that a large quantity of it is discharged in the fermentation of alimentary mixtures2 and that the saliva being1 in a healthy state1 void of air1 acts as an absorbent of it1 thereby moderating and restraining the discharge of this vapour in the stomach4 ,but when the tone of that viscus is too relaxed to perform the digestion of the aliment with proper vigour1 or the saliva is diseased and corrupted1 the air expelled from the food becomes too elastic1 and produces those disorders which are commonly termed flatulent2 and1 perhaps1 by its effects on that prodigious plexus of nerves which is diffused over the coats of the stomach1 may sometimes occasion spasmodic or paralytic affections4 ,it has been observed above1 that calcareous earths1 alkaline salts1 and ,magnesia1 being deprived of their air1 attract it from every substance with which it has a smaller degree of affinity4 ,the two former becoming highly caustic by the loss of their air cannot be administered but in very small doses4 ,but the calcined ,magnesia being absolutely divested of air1 though not rendered acrimonious1 and being able to absorb a large quantity of this elastic flatus1 may act more powerfully than the whole tribe of carminatives1 yet essentially differs from them in many respects4 ,they contain a large quantity of air2 ,magnesia in this state is entirely free from it2 ,aromatics may be apt to ferment1 and increase acidities2 the calcined ,magnesia is incapable of effervescence1 and powerfully corrects an acescent disposition in the gastric juices2 the former constipate the belly2 the latter is laxative4 ,from this property of ,magnesia1 when calcined1 of absorbing air1 it occurred to me1 that it would of all others be the most proper cathartic for patients labouring under the stone1 who might be taking the lixivium saponarium1 having the advantage over all the vegetable purgatives1 which abound with air1 and consequently have a tendency to render the caustic alkali mild and inert4 ,i even flattered myself that it might coincide in promoting the efficacy of that powerful solvent of the human calculus4 ,dr4 ,macbride's theory1 that the lixivium acts by depriving the calculus of its fixed air1 appears to be well founded2 and ,mr4 ,chittick in the exhibition of his nostrum1 which1 notwithstanding all his empirical arts to disguise it1 is now known to have been the soap ley1 kept his patients from every kind of diet abounding with air4 ,we may therefore venture to recommend it1 though not as a lithontriptic1 being insoluble in water1 yet as an assistant to the lixivium1 by absorbing a part of that air in the prim vi which would otherwise be attracted by the caustic alkali1 and thereby render it incapable of acting on the calculus4 ,in all the diseases attended with an acescent disposition in the first passages1 in which ,magnesia has been recommended in the third chapter1 the calcined powder may be given with superiour advantages1 as it will not produce any of those inconveniences1 which have been attributed to that medicine when uncalcined4 ,besides that it will act in a three-fold capacity1 viz4 as an absorbent of air1 and of acidity1 and also as an easy purgative4 ,i know several persons who could never bear to take the common ,magnesia1 with whom the calcined perfectly agrees4 ,it seems likely to be very serviceable in flatulent cholics1 and ,i have been informed of one very obstinate chronical case of that kind1 which was greatly relieved1 though not perfectly cured by the use of it in the ,chester ,infirmary1 under the direction of a very judicious and ingenious physician4 ,even in gouty habits1 joined with some warm aromatic1 it may probably be found useful in correcting the very great flatulency which so much afflicts persons of this constitution2 and perhaps the ,cayenne pepper would be the most proper addition to it1 on account of the small quantity of this spice that would be necessary to make the ,magnesia gratefully warm to the stomach4 ,it will appear in the succeeding chapter that calcined ,magnesia is strongly antiseptic3 but ,i shall postpone my observations on that subject till ,i have related the experiments which prove its claim to that property4 ,,chap4 ,,vi4 ,,on ,,the ,,action ,,of ,,various ,,absorbents ,,as ,,promoting ,,or ,,retarding ,,putrefaction4 ,the whimsical and ill-grounded hypotheses which were framed by the chymists of the sixteenth century1 had1 unhappily1 too much influence1 on the medical practice of that and the succeeding age4 ,among other false theories which the physicians had adopted from them1 was that of attributing the origin of most diseases either to an acid or alkaline cause3 but the former1 being more obvious to the senses1 was supposed to be the most frequent parent of diseases4 ,among others1 fevers1 even of the putrid kind1 were imagined to be occasioned by an acid1 and from hence the testaceous medicines acquired so high a degree of reputation1 as to be deemed the grand correctors of acrimony1 and were almost universally prescribed as alexipharmics2 and the most celebrated compositions which are ranged under that head1 contain a large proportion of these powders4 ,but a very learned physician1 by a series of accurate and ingenious experiments on septics and antiseptics1 has proved that chalk and all the testaceous powders accelerate the corruption of animal flesh1 and from the result of one he made on bile with crab's eyes1 he naturally concluded that all these substances would produce the same effect on that humour1 as they had all uniformly proved septic to flesh4 ,yet1 even upon this supposition1 he candidly allows1 that in some fevers1 they may have their uses1 even where no offending acid exists2 as in order to cure some diseases1 it may be requisite to attenuate the humours1 and relax the fibres by a degree of putrefaction1 and that possibly the crisis of fevers of this kind1 may be hastened or perfected by the testaceous powders4 ,in diseases1 however1 where the disposition to putrescency is already too strong1 all medicines1 which in the smallest degree increase such tendency should be studiously avoided2 and1 on this account1 the administration of the testacea in putrid1 malignant fevers has of late been condemned by some ingenious writers4 ,i was myself fully convinced of the rectitude of this opinion1 and1 in drawing up an account of the medicinal uses of ,magnesia1 had therefore suggested the impropriety of prescribing them where a bilious acrimony prevails4 ,but not being able to recollect1 that the septic powers of ,magnesia had ever been experimentally proved1r ,i thought it would be most satisfactory to determine them by that method2 little doubting but that the event would justify my doctrine4 ,my inquiries evince the accuracy with which ,sir ,john ,pringle has made his experiments1 but as ,i was induced to carry the investigation of this subject further than he has proceeded1 very different practical inferences1 from those ,i at first expected1 may1 perhaps1 be deduced therefrom4 r ,i at that time overlooked an experiment of ,dr4 ,macbride's which proves ,magnesia to be septic to animal flesh2 but having met with it just before these papers were going to the press1 ,i take this method of acknowledging it4 ,,experiment ,,ii4 ,two drachms of fresh beef1 two scruples of ,magnesia1 and two ounces of distilled water were mixed in one bottle2 and in another the same quantity of beef with two ounces of distilled water only3 the meat was cut small1 and the bottles were placed uncorked in a heat rather inferior to that of the human blood4 ,in twenty four hours the beef in the mixture with ,magnesia was become quite putrid4 ,the standard was perfectly sweet1 and remained for some days1 before it acquired the true putrid foetor4 ,being thus convinced that ,magnesia is possessed of the property of hastening the putrefaction of animal flesh1 in common with the rest of the absorbent tribe1 it was imagined1 that it might be of some consequence to practice1 to determine how far it exceeded or was inferiour to the calcareous and testaceous earths as a septic2 and also whether calcination produced any difference in it1 in this respect4 ,in reciting the experiments1 where ,i only mention ,magnesia1 ,i always would be understood to mean that powder in its uncalcined state1 the calcined shall constantly be distinguished by that epithet4 ,it also appeared to be a convenient opportunity of repeating the inquiry1 how far the addition of the testacea might take effect in diminishing the antiseptic qualities of the contrayerva root4 ,,experiment ,,iii4 ,into one phial were put two scruples of ,magnesia1 into a second the same weight of calcined ,magnesia1 and into three others the same quantity of chalk1 pulv4 e chel4 cancr4 comp4 and pulv4 contrayerv4 comp4 ,to each of these1 two drachms of fresh beef1 and two ounces of distilled water were added4 ,a sixth phial was kept as a standard1 and contained only the same proportions of beef and water4 ,the bottles1 distinguished in the order they are mentioned by the numbers #a1 #b1 #c1 #d1 #e1 and #f1 were placed in the same heat as that to which the ,magnesia was exposed in the former experiment1 and were frequently shaken up and examined4 ,in twelve hours1 number #a began to smell2 an intestine motion was perceptible in numbers #c1 #d1 #e1 and #f1 but especially in the chalk4 ,in twenty-four hours1 number #a was become highly putrid1 number #c smelled offensively1 number #d had acquired a very slight foetor1 as had number #e which fermented briskly4 ,the standard had acquired a vinous smell1 but number #b remained unchanged4 ,in thirty six hours1 number #c was very putrid1 numbers #d and #e had made little progress since the last examination1 though number #e was rather more putrid than the other1 allowance being made for the peculiar odour of the contrayerva2 but in four hours more they both stunk intolerably4 ,the standard continued two or three days longer before it became absolutely putrid1 and the calcined ,magnesia preserved the beef untainted for several days longer1 when it was removed to make room for other phials4 ,the water which was mixed with the calcined ,magnesia differed from all the others in not becoming bloody1 nor did the beef in it seem so tender as when infused in lime water4 ,when ,i made the first experiment1 ,i had not observed any discharge of air from the ,magnesia and beef1 and in the present one no fermentation was perceptible either in number #a or #b4 ,as this was an unexpected circumstance in the former1 ,i repeated the experiment several times1 but the event was always the same4 ,magnesia was afterwards compared with crab's eyes1 burnt hartshorn1 and prepared coral4 ,the mixture with ,magnesia grew putrid first1 afterwards that with the crab's eyes2 the other two remained for some hours longer before the putrid foetor came on4 ,from the above experiments it appears that ,magnesia ,alba1 when replete with fixed air1 is a stronger septic to animal flesh than any other absorbent which was compared with it2 and yet when deprived of its air by calcination1 it powerfully resists putrefaction4 ,dr4 ,macbride has endeavoured to account for this difference between calcareous earths and quick-lime1 by supposing the particles of the lime to insinuate themselves intimately into the texture of the beef1 and to prevent the escape of the fixed air1 by attracting1 absorbing1 and thus confining it within the substance of the beef4 ,how far this theory is satisfactory is not my province to determine2 and the matter is so obscure1 that ,i do not presume to offer any conjecture of my own1 relative to the reason of it4 ,nitre is found to be a strong antiseptic when applied to animal flesh1 but to resist the putrefaction of bile with a very disproportionate force3 and ,dr4 ,percival has lately observed the same difference in the action of the ,columbo root4 ,these variations encouraged me to try the effect of ,magnesia on gall2 but being strongly prepossessed with the notion of its septic quality1 ,i entertained very small hopes of a different event4 ,i was also desirous to compare the action of the calcined ,magnesia with the other4 ,the heat used in the succeeding experiments was the same as that in the preceding trials4 ,,experiment ,,iv4 ,to two drachms of fresh ox gall1 were added two scruples of ,magnesia1 and two ounces of water1 in one phial4 ,two scruples of calcined ,magnesia with the same quantity of gall and water were placed in another2 and a third containing two drachms of bile without any other addition than water1 served as a standard1 which began to have a rank smell in forty-eight hours1 and in sixty hours was highly offensive4 ,the calcined ,magnesia and bile emitted a sweetish smell1 something resembling that of the urine in a diabetes3 the liquor which swam above was quite pellucid and colourless1 whereas that of the other ,magnesia was turbid and tinged green with the bile4 ,both were perfectly free from any putrid foetor2 the latter continued so for ten days1 and the bile with the calcined ,magnesia remained unchanged as long as any notice was taken of it4 ,,experiment ,v4 ,twenty grains of ,magnesia preserved six drachms of ox's gall free from any signs of corruption for twenty-four hours after the standard containing gall and water1 of each six drachms1 had become putrid4 ,a scruple of the calcined ,magnesia mixed with the same proportions of gall and water1 remained without any alteration as long as they were attended to1 which was about ten days4 ,,experiment ,,vi4 ,the putrid liquor which had been used as a standard in the fourth experiment1 was divided into four parts1 one of which was continued as a standard1 to another was added about half a drachm of ,magnesia1 and an effervescence was procured by some drops of oil of vitriol4 ,the offensive smell continued for a few minutes1 but was soon much abated1 and at length entirely sweetened4 ,to another portion was added twenty grains of ,magnesia only1 this in fifteen minutes had almost lost its putrid smell1 and in two or three hours became quite sweet4 ,to the fourth was added the same weight of calcined ,magnesia1 which almost instantly deprived the liquor of every degree of putridity4 ,the standard was then mixed with a scruple of crab's eyes1 which1 for about a minute1 seemed to diminish the foetor1 but it then returned as strongly as ever2 whereas the others continued sweet for several days4 ,,experiment ,,vii4 ,two drachms of putrid bile1 which had been kept closely corked in a phial since the year #aggj1 and smelled very offensively1 were mixed in a cup with twenty grains of ,magnesia1 and half an ounce of water1 and thereby restored to sweetness4 ,twenty grains of calcined ,magnesia were also added to two drachms of the same bile3 on stirring them a pungent smell was observed1 like that of volatile salts1 and half an ounce of water being put to the mixture1 the bile was totally deprived of any putrid smell4 ,even five grains of the same powder sweetened two drachms of putrid gall4 ,,experiment ,,viii4 ,magnesia1 calcined ,magnesia1 chalk1 crab's eyes1 pulv4 e chel4 cancr4 c4 and pulv4 contrayerv4 comp4 each in the proportion of two scruples to two drachms of ox gall and two ounces of water1 were exposed to the usual warmth4 ,the crab's eyes mixture grew rank in twenty-four hours1 and in forty-eight was absolutely putrid3 the bile with the chalk was in the same condition in twelve hours more4 ,the ,magnesia mixture became putrid on the ninth day2 the pulvis e chel4s on the tenth2 but the pulvis contrayerv4 comp4 preserved the bile from corruption about three weeks1 and no change was perceptible in that with the calcined ,magnesia when examined above a month after their first admixture4 s ,doctor ,macbride found that pulv4 e chel4 c4 c4 hastened the corruption of bile3 might not this depend on some variety in the composition of that powder8 ,chalk and oyster shells are often substituted in the hospitals and by the druggists1 for the other ingredients4 ,,experiment ,,ix4 ,twenty grains of ,magnesia1 and the same quantity of chalk1 were separately neutralized with distilled vinegar1 and their effects on ox gall compared with that of thirty grains of the artificial ,epsom salt dissolved in a sufficient quantity of water4 ,the bile in this solution became putrid in about sixty hours4 ,that in the solutions made in the vegetable acid retained its sweetness for several days longer4 ,these experiments1 which terminated so very differently from what ,i had expected1 seem to justify1 in some degree1 the practice of giving the testaceous and absorbent medicines in fevers of a putrescent type1 at the same time that they point out some of that class which ought to be avoided1 and evince how fallacious a method it is to judge of the effects of medicines a priori4 ,as the bile is1 by many1 supposed to be the great source of putrid diseases1 ought not the antiseptics which may be prescribed in these cases1 to be such as more particularly impede the corruption of this fluid1 rather than that of flesh8 ,on account of the superiour antisepticity of the calcined ,magnesia to most of the absorbents1 and its greater purity and solubility1 together with the probability of its acting as an evacuant1 as well as a corrector of putrid bile1 does it not appear to merit a preference to all other medicines of this class8 ,in diseases where an acid cacochymy prevails1 and an alkalescent diet1 such as wild fowl1 fish1 c4 is prescribed1 but from the scarcity of these articles in some countries1 cannot be complied with2 may not taking ,magnesia or the testaceous powders1 immediately before or after meal time1 coincide with this intention1 by increasing the putrefactive fermentation of other animal food in the stomach1 which in these disorders is almost totally subdued by the superabundant acid8 ,but where animal food is used in putrescent diseases1 either through necessity1 or the obstinacy of the patient1 ought not ,magnesia1 in an uncalcined state1 and all the calcareous and testaceous earths to be carefully abstained from8 ,dr4 ,percival1 in a volume of very ingenious experiments and observations which have been before referred to1 has mentioned a physician of his acquaintance1 who always observed his stools to be more particularly offensive after having taken ,magnesia4 ,might not this proceed from the action of the ,magnesia on the animal food he had eaten2 and is it not reasonable to suppose that the effect might have been very different where a vegetable or milk diet had been used1 as is generally the case in putrid fevers1 and in young children8 ,i know a person whose stools are1 in common1 very little tinged with bile1 who after taking calcined ,magnesia1 evacuates fces of a very bilious appearance1 though less foetid than usual4 ,it is a fact worthy of observation1 that in the experiments which were made with calcined ,magnesia and bile1 the latter was absorbed by1 and had united with the former2 and another remarkable circumstance was1 that the watery part of all the mixtures which resisted putrefaction1 acquired a very pungent1 saline taste4 ,,chap4 ,,vii4 ,,on ,,the ,,solvent ,,qualities ,,of ,,calcined ,,magnesia4 ,dr4 ,macbride1 whose experimental researches have very justly acquired him a high degree of reputation in the philosophical world1 supposes fixed air to be the combining principle of bodies1 and has applied this ingenious theory to pharmaceutical improvements4 ,he discovered that lime triturated with resinous gums1 promotes their dissolution in water2 which1 he thinks1 is thus enabled to take up the same parts of these substances1 as are soluble in spirit of wine4 ,these aqueous tinctures are transparent1 not milky like the solutions made with yolk of egg1 or gum arabic2 but the lime communicates a highly disagreeable taste to them1 and the action of lime water1 which he used in some instances1 is not sufficiently powerful to extract strong tinctures from these bodies4 ,as calcined ,magnesia has a great affinity with fixed air1 ,i was desirous of trying whether it would contribute to render resinous substances soluble in water2 for being itself insoluble1 the solutions would consequently be free from any other impregnation than that of the resins4 ,,experiment ,x4 ,five grains of camphor were rubbed for five minutes with an equal quantity of calcined ,magnesia3 after the camphor was reduced to powder1 it united into a hard concrete with the ,magnesia1 but immediately dissolved on the addition of a small quantity of distilled water1 of which an ounce was mixed with them1 and immediately passed through filtering paper4 ,the filtrated liquor was highly impregnated with the camphor4 ,,experiment ,,xi4 ,five grains of opium triturated in the same manner1 yielded a transparent tincture1 of as deep a colour as the tinctura ,thebaica of the ,london ,dispensatory1 and tasting strongly of the opium4 ,,experiment ,,xii4 ,gum guaiacum and calcined ,magnesia1 of each a scruple1 being rubbed with an ounce of water1 and filtered1 gave an elegant green tincture1 quite transparent1 and possessing1 in a considerable degree1 the taste of the gum4 ,gum galbanum1 storax1 mastick1 myrrh1 assaftida1 scammony and balsam of ,tolu1 being severally triturated with equal weights of calcined ,magnesia1 diluted with water and filtered1 afforded neat tinctures1 strongly impregnated with the different drugs4 ,,experiment ,,xiii4 ,in order to determine the quantity of opium thus dissolved1 half an ounce of crude opium1 the same quantity of calcined ,magnesia1 and eight ounces of distilled water were rubbed for a quarter of an hour in a glass mortar1 and having stood to infuse during two hours1 the liquor was separated through paper4 ,the tincture was of a darker colour than that before described1 and was reduced by a gentle heat to a pilular consistence4 ,this extract weighed sixty-eight grains1 which1 allowing for impurities1 for what would be dissipated in evaporation1 and for the air probably absorbed by the ,magnesia1 is a large proportion to be so soon dissolved4 ,the residuum which was left in the filter was dried1 and weighed six drachms4 ,,experiment ,,xiv4 ,a drachm of ,peruvian bark1 twenty grains of calcined ,magnesia1 and four ounces of distilled water being rubbed together during fifteen minutes1 the filtered infusion resembled in appearance the simple tincture of bark1 and had an intensely bitter taste1 but was not strongly impregnated with the peculiar aroma of the bark4 ,thus then we have an easy and very elegant method of preparing aqueous tinctures from the gum resins1 and administering them in a more convenient form and in larger doses than could be done when dissolved in a spirituous menstruum2 and much more agreeably than in the half-dissolved state to which they are reduced by the aid of egg or gum arabic4 ,the ,magnesia does not impart any thing to them1 whereas the lime will seldom be so saturated with air but that some part of it will remain soluble in the water3 and as they may be given diluted to whatever degree the prescriber chuses1 considerable advantages may be expected therefrom1 it being probable that they will be better enabled to pervade the very small vessels2 and the heating properties of the balsams be more effectually obviated than by any other mode of preparation4 ,indeed1 tinctures prepared by the above method1 are not calculated for officinal compositions1 but for extemporaneous prescription2 as most of them1 except camphor1 deposite a sediment when they have been kept a week or two4 ,,chap4 ,,viii4 ,,on ,,the ,,various ,,solvent ,,powers ,,of ,,quick-,,lime ,,in ,,different ,,quantities4 ,the difficulty of solution in the vegetable astringents has been complained of by various writers on the ,materia ,medica4 ,water and alcohol are the menstrua in use2 but great quantities of each are necessary to procure even a slight impregnation1 and much heat and long boiling are said actually to destroy the astringent quality1 and vegetable texture4t ,as a menstruum capable of dissolving them with greater facility appeared to be a desideratum1 not only in pharmacy1 but in other arts1 particularly in that of dying blacks1 ,i resolved to try ,dr4 ,macbride's method of increasing the solvent power of water1 by means of quick-lime4 ,but as ,i was aware that the quantity of lime he made use of in obtaining an aqueous tincture of ,peruvian bark1 would be too great for the dyer's use1 ,i wished to use only such a quantity as would be sufficiently saturated with the air contained in the vegetable1 to be itself precipitated2 and to compare the tinctures thus made1 with a standard prepared with simple water4 t ,vid4 ,lectures on the ,materia ,medica1 as delivered by ,william ,cullen1 ,m4,d4 p4 #aie4 ,,experiment ,,xv4 ,i rubbed three drachms of ,aleppo galls reduced to powder1 with four ounces of filtered rain water1 for fifteen minutes1 and then passed the solution through paper4 ,it was very styptic to the taste1 and was nearly of the same colour as ,huxham's tincture of bark4 ,the residuum in the filter was unchanged in colour4 ,the bottle containing the liquor was marked number #a4 ,,experiment ,,xvi4 ,three drachms of the same galls1 and two scruples of quick-lime1 were triturated with four ounces of rain water1 as in the last experiment4 ,the filtered liquor had scarcely any astringency to the taste1 and was of a very pale colour4 ,the residuum was of a deep purple4 ,marked number #b4 ,,experiment ,,xvii4 ,the same quantity of galls as in the two former experiments1 after triture in the same degree with four ounces of lime-water1 was separated by filtering through paper4 ,the tincture thus obtained was highly astringent to the palate1 of a deep chocolate colour1 and the residuum was of a lighter brown than number #a4 ,marked number #c4 ,,experiment ,,xviii4 ,to each of the above tinctures were added forty drops of a strong solution of sal martis4 ,number #a became very black4 ,number #b changed colour but little1 and on standing precipitated a brown sediment1 which1 the superiour part of the liquor being decanted off1 became again transparent on the addition of a few drops of the vitriolic acid4 ,number #c appeared to strike a deeper black than number #a2 and these being tried as inks1 number #c seemed to have the superiority2 but a slip of linen cloth being macerated in each for some hours1 that in number #a had taken a more perfect black than the slip number #c4 ,no trial was made with cotton or woollen1 which it is probable would have differed from the linen4 ,,experiment ,,xix4 ,oak bark was used instead of galls1 with similar success1 except that the infusion made with lime-water was not so deep in colour as that with simple rain water1 though much deeper than that prepared with quick-lime4 ,,experiment ,,xx4 ,peruvian bark1 quick-lime1 and lime water1 in the same proportion as directed by ,dr4 ,macbride1 were rubbed together4 ,the filtered infusion had little colour1 tasted very slightly of the bark1 though strongly of the lime1 and on my blowing in a stream of air from my lungs1 the surface of it was immediately covered with a cremor calcis1 the liquor grew turbid1 and deposited a copious sediment4 ,,experiment ,,xxi4 ,the same quantity of ,peruvian bark1 and of lime water1 without the addition of any fresh lime1 being rubbed in the same manner1 afforded a tincture tasting strongly of the bark1 nearly of the same colour as the simple tincture obtained by proof spirit1 and retaining its transparency when blown into4 ,this tincture was much more strongly impregnated than one made by triture with common rain water only4 ,and by this process1 allowing a few hours for maceration1 an infusion is prepared1 greatly superiour in strength to any decoction1 infusion1 or tincture of bark ,i ever saw4 ,from the result of these experiments ,i suspect1 that by using a greater quantity of lime in the sixteenth and twentieth experiments than the vegetable could saturate with fixed air1 the water became so impregnated with lime as to be more unfit to act on the vegetable4 ,from the purple colour of the residuum of number #b1 it was evident that the galls were decompounded1 but the water was not capable of dissolving and suspending the particles4 ,dr4 ,percivalu mentions his having unsuccessfully repeated ,dr4 ,macbride's experiment with bark and quick-lime4 ,to what then can this difference be owing8 ,perhaps it may be accounted for thus3 ,it seems probable that the lime used by ,dr4 ,macbride1 not being fresh calcined1 had recovered part of its air2 for he says1 ,it will no doubt be reckoned superfluous1 that lime water is ordered to be added to these several substances1 when they are also to be rubbed along with quick-lime2 but the reason is this4 ,if the lime were so quick and fresh as to raise heat when common water is poured on it1 the solution might then be made without the aid of lime water2 but1 as it will for the most part happen1 that the lime kept in the shops will not be perfectly fresh1 it will be best that the prescriber should direct lime water to be used4 ,on the contrary1 ,dr4 ,percival used lime fresh from the kiln4 ,these circumstances1 if my theory be just1 would greatly vary the event of the experiment2 and the trials ,i have here recited seem to prove1 that so great a quantity of lime1 and even a much smaller than is directed by ,dr4 ,macbride1 if fresh1 instead of increasing1 diminishes the solvent power of water on astringent vegetables4 u ,percival's ,essays ,medical and ,experimental1 #b;d ,edit4 p4 #fe4 ,but as different drugs yield their virtues with more ease1 and in greater quantity to some menstrua than to others1 it seemed probable1 that even a very small quantity of lime might render water less solvent of particular vegetables1 than it is in its pure state1 though with others as large or perhaps a greater quantity than what ,i had used might be necessary3 and as the determination of this point might be of some use in pharmacy1 the following experiments were made2 in the relation of which ,i shall make use of numbers as before1 viz4 the vegetable rubbed with four ounces of distilled water will be distinguished by number #a1 that with two scruples of lime and four ounces of lime water1 number #b1 and that with lime water only1 number #c4 ,,experiment ,,xxii4 ,two drachms of snake root were rubbed for fifteen minutes with the above-mentioned different proportions of distilled water1 quick-lime and lime water1 and lime water alone4 ,number #a was a dark brown tincture1 tasting strongly of the serpentaria4 ,number #b1 straw coloured1 taste of the lime disagreeable1 that of the root not distinguishable4 ,number #c1 amber coloured1 tastes of the root4 ,,experiment ,,xxiii4 ,two drachms of ,columbo being triturated in the same manner1 ,number #a1 dark brown tincture2 tastes much of the ,columbo4 ,number #b1 yellow2 faint taste of the ,columbo1 but that of the lime very disagreeably prevalent4 ,number #c1 colour as number #a2 but tastes more highly of the ,columbo4 ,,experiment ,,xxiv4 ,two drachms of contrayerva root with the same treatment yielded in the following proportions3 ,number #a gave a pale brown tincture1 tasting of the contrayerva4 ,number #b1 bright amber colour2 taste of the lime so strong as to admit of no other4 ,number #c exceeded number #a both in colour and taste4 ,,experiment ,,xxv4 ,jalap being triturated in the same proportions1 ,number #a dark brown2 taste of the jalap strong4 ,number #b pale yellow2 taste of the lime predominant1 though that of the jalap perceptible4 ,number #c1 colour not quite so high as number #a1 but equal in taste4 ,,experiment ,,xxvi4 ,the result of the same trial with ipecacuanha was1 that number #a was of a light brown colour1 tasting highly of the ipecacuanha4 ,number #b was of a deep yellow1 having the same disagreeable taste of the lime complained of in the other tinctures1 but that of the ipecacuanha scarcely perceptible4 ,number #c produced a tincture of the colour of red port wine1 strongly flavoured with the ipecacuanha1 though it had not so much of the distinguishing sharpness of that root as number #a4 ,,experiment ,,xxvii4 ,the different tinctures of rhubarb1 prepared in the same manner as above1 had the following appearances3 ,number #a brown1 with a yellowish tinge1 strongly impregnated with the taste of the rhubarb4 ,number #b deep yellow1 taste of the lime as in the other tinctures prepared with it4 ,number #c crimson2 taste of the rhubarb strong1 but unequal to number #a4 ,none of the tinctures prepared with lime water grew turbid from a stream of fixed air being conveyed into them4 ,hence it appears that the triture of quick-lime with all the above roots did not in the least degree promote1 but rather impede their solution in water2 that lime water extracts the soluble parts of many1 and especially their colouring principles1 more powerfully than distilled water2 but that this is by no means always the case1 as in three instances out of six1 the tinctures prepared with distilled water exceeded those with lime water in taste1 and in two instances were superiour1 and in one equal in colour4 ,,chap4 ,,ix4 ,,on ,,the ,,comparative ,,antiseptic ,,powers ,,of ,,vegetable ,,infusions ,,prepared ,,with ,,lime1 c4 ,sir ,john ,pringle1 in the ,appendix to his excellent ,observations on the ,diseases of the ,army1 allows lime water to possess but a slight antiseptic quality4 ,doctor ,macbride on the contrary asserts1 that it has great power in resisting putrefaction1 but at the same time acknowledges that it destroys the cohesion of the constituent particles of animal substances1 and therefore cannot be called a true antiseptic1 as it absorbs the fixable air from them1 and only preserves them sweet by confining it within their texture1 into which the lime is enabled to insinuate itself in this dissolved state4 ,as even this effect1 if possessed by the tinctures of the antiseptic vegetables prepared with lime or its water1 would be an objection to their administration in putrid diseases1 ,i resolved to determine by experiment1 how far their antiseptic powers were increased or diminished by this mode of preparation3 and ,i thought it probable1 as those prepared with the latter contain no lime when filtered1 and yet in the extraction of the tinctures the vegetables are deprived of1 at least1 a part of their air1 they might be rendered less able to resist putrefaction than either the infusions prepared with distilled water1 or those with the addition of quick-lime4 ,how far this reasoning was just1 the result will discover4 ,,experiment ,,xxviii4 ,pieces of beef1 each weighing about two drachms1 were separately infused in the different tinctures of ,peruvian bark1 snake root1 ,columbo1 and contrayerva1 prepared with lime1 lime water1 and distilled water1 as in the preceding experiments2 and the bottles containing them were exposed for two days to a degree of heat equal to that of the human blood4 ,they were afterwards suffered to remain without any artificial heat1 the temperature of the air being warm4 ,the tincture of ,columbo prepared with quick-lime was the only one not tried1 the bottle containing it having been broken4 ,after thirty-six hours infusion they were all sweet1 except the infusion of ,columbo in distilled water1 which began to emit a disagreeable1 though not putrid foetor4 ,the beef in it1 and in the tincture of the same root in lime water1 was swelled1 and whiter than before infusion4 ,that in the tincture of bark prepared with quick-lime1 had its texture greatly destroyed1 was of a chocolate colour1 but sweet4 ,that in aqua calcis1 the same in colour1 shrivelled1 firm1 and sweet4 ,the pieces of beef in the tinctures of snake root and of contrayerva with quick-lime1 had more the appearance of calf's lights than of beef1 were quite spongy1 but had acquired no putrid smell4 ,those in the lime and distilled water1 firm1 and shewing no signs of putrescency4 ,on the fifth day the infusion of ,columbo in lime water was very offensive1 though the beef when taken out of it was not putrid4 ,that of the same root with distilled water had made no further progress4 ,the tincture of snake root in distilled water was grown turbid1 and had lost colour1 which it seemed to have imparted to the beef4 ,this and all the others continued sweet4 ,on the tenth day the beef in the distilled water and ,columbo1 as on the fifth4 ,that in the lime water and ,columbo1 putrid4 ,the contrayerva infusion in distilled water had acquired a disagreeable foetor1 but the beef was not yet putrid4 ,that with lime water and that with quick-lime still sweet4 ,the infusion of bark with distilled water smelled rather musty2 the beef in it sweet4 ,the two infusions of the same with lime and lime water shewed no further change4 ,the tincture of snake root in distilled water had a scum on the surface2 beef not putrid4 ,the other two tinctures of the same root unchanged4 ,on the eleventh day1 the beef in the infusions of ,columbo and of contrayerva in distilled water beginning to putrefy1 and ,on the fourteenth day1 both entirely putrid4 ,the infusion of bark in distilled water mouldy1 but the beef sweet4 ,the beef in the snake root and distilled water1 putrid on the sixteenth day2 and the infusion of contrayerva with lime water beginning to be offensive1 but the beef in it not yet putrid2 but ,on the nineteenth it was quite putrefied4 ,the snake root infusion in lime water1 mouldy on its surface2 no change in the beef2 but this likewise became putrid in a few days more4 ,the remaining tinctures1 viz4 those of the bark1 snake root1 and contrayerva with quick-lime1 and that of the bark with lime water1 remained above five weeks without any further change4 ,some time after1 the beef in the snake root became septic4 ,the other three were unaltered at the end of six weeks from their first immersion2 and though the infusion of bark in distilled water was very mouldy1 the beef in it was free from any putrid foetor4 ,but it should be observed that all the tinctures in the preparation of which quick-lime had been added to the lime water1 had a peculiar odour during the whole time1 from which the others were exempt4 ,from this experiment we may conclude that lime water1 when used in such a quantity in extracting the virtues of vegetables1 as not to be saturated with the fixed air it receives from them1 strongly counteracts putrefaction1 though it at the same time destroys the texture of animal bodies exposed to its action4 ,but when employed for the same purposes1 in such proportion as to be fully saturated with air2 it abstracts nothing from1 but rather increases the antiseptic power of the vegetable2 nor does animal flesh immersed in tinctures thus prepared1 suffer any diminution in the cohesion of its fibres4 ,,chap4 ,x4 ,,on ,,the ,,sweetening ,,properties ,,of ,,fixed ,,air4 ,the very curious fact1 that fixed air not only preserves bodies from becoming septic1 but is also possessed of the power of restoring sweetness to them when actually putrid1 seemed to be established by a number of very accurate experiments adduced in support of the doctrine by its ingenious author4 ,this has1 however1 lately been controverted by a learned writer1 who has favoured the public with an ,experimental ,inquiry concerning the causes which have been generally said to produce putrid diseases1 in which he has recounted several experiments1 in direct contradiction to those of ,dr4 ,macbride4 ,the authorities of both these gentlemen deserve considerable attention1 and it might seem presumption in me to attempt to decide between them1 had ,i only my own opinion to adduce2 but as the accuracy of the following trials was witnessed by a ,physician1 well known for his medical and philosophical writings1 ,i feel the less diffidence in submitting them to the public4 ,they were made with a view1 only1 to my own information1 having in one of the former chapters recommended ,magnesia to be taken in the act of effervescence with an acid1 as a corrector and evacuant of putrid bile2 but as the event appeared to be so satisfactory1 and as a determination of this point is the more important1 from the late introduction of fixed air as an article of the materia medica1 ,i hope ,i shall not be deemed to have impertinently obtruded into the dispute by relating them1 and endeavouring to point out what1 probably1 has been the cause of ,dr4 ,alexander's drawing conclusions1 so contrary to those of the other celebrated experimentalist4 ,in the experiments which ,dr4 ,alexander has related in support of his opinion1 he has made use of the following methods4 ,he included pieces of putrid mutton in bladders1 one containing four ounces in measure of fixed air from fermenting wort2 another the same quantity from wort with a piece of putrid mutton in it2 and the third1 only about half the quantity from a mixture of bread1 water1 and saliva4 ,in another experiment1 he exposed a slice of beef that had just begun to have the putrid smell1 to a stream of air brought over from an effervescing mixture of distilled vinegar and salt of wormwood4 ,in a third1 the putrid flesh was suspended in the neck of a wide mouthed bottle1 while four ounces of distilled vinegar were made into spirit4 minderer4 ,in a fourth1 four ounces of air from bottled small beer were confined twenty-four hours with the putrid substance1 which in a fifth experiment was put into the neck of a bottle of small beer1 while it fermented before the fire for half an hour4 ,in a sixth1 the septic body was included in a bottle with eight ounces of air from an effervescing mixture of common vinegar and salt of hartshorn4 ,in one only1 out of all these experiments1 he found the beef in any-wise sweetened1 and even in that single instance1 though he at first thought the piece a little changed1 yet when washed it recovered its putrid smell4 ,however he confesses1 that by bringing over fixed air from several other fermenting and effervescing mixtures1 on pieces of meat just beginning to putrefy1 they were rendered a little sweeter1 though never to such a degree1 as entirely to lose their putrid taint4 ,so very different an account of so interesting a subject was truly mortifying3 ,the old adage1 experientia fallax1 judicium difficile1 seemed to be too applicable to the present occasion4 ,some cases1 in which fixed air used medicinally as an antiseptic1 appeared to have produced good effects1 had occurred to some of my medical friendsv1 and ,i even flattered myself that ,i had directed it to good purpose in an instance or two4 ,but if the theory on which this practice was founded should be false1 the whole superstructure seemed likely to be destroyed4 ,on revising ,dr4 ,alexander's book1 ,i imagined that ,i had discovered some thing in the conducting of his experiments1 which might account for their terminating so differently from those of ,dr4 ,macbride4 v ,see ,dr4 ,percival's ,experiments and ,observations1 p4 #gb2 ,dr4 ,priestley's papers on factitious air2 and ,mr4 ,white's ,treatise on the ,management of ,pregnant and ,lying-in ,women1 p4 #bjc4 ,the largest quantity of fixed air which ,dr4 ,alexander made use of in any of these experiments was eight ounces in measure1 and in one instance1 only two ounces were employed to sweeten the putrid substance4 ,in that where the meat was suspended in a wide mouthed bottle while the vinegar was made into spirit4 minderer4 no method seems to have been taken to retard the too rapid flight of the fixed air1 which1 from the quick distribution of the salt1 would be soon dissipated4 ,from hence ,i suspected1 that a larger atmosphere1 or a longer continued stream of fixed air might be requisite to restore septic bodies to perfect sweetness2 and in order to decide this point1 the following experiments were instituted1 having previously obtained some slices of beef so exceedingly putrefied as to render the foetor of them scarcely tolerable4 ,,experiment ,,xxix4 ,a bottle capable of containing three pints was filled with water1 and inverted into a bason of the same2 a tube which communicated with another bottle1 in which was an effervescing mixture of chalk and oil of vitriol1 was then introduced into the mouth of the former1 and a stream of fixed air continued1 till the whole of the water was driven out by it4 ,a piece of the above-mentioned putrid beef1 fastened by a string to a cork1 was conveyed into the bottle1 which was corked before it was taken out of the water4 ,the beef1 after having been suspended in this atmosphere of fixed air for thirteen hours1 was very considerably1 though not entirely sweetened4 ,but the air in the bottle seemed to have acquired all the putrid smell of which the flesh had been deprived4 ,another slice of the same beef was not at all sweetened by exposure1 during the same time1 to the open air4 ,,experiment ,,xxx4 ,a piece of this beef suspended all night in the neck of a bottle of artificial ,pyrmont waterw1 was rendered less putrid1 though not near so much altered as that in the foregoing experiment4 ,the water was strongly impregnated with the putrid effluvia4 w ,see ,dr4 ,priestley's ,directions for impregnating ,water with fixed ,air4 ,,experiment ,,xxxi4 ,two drachms of ,magnesia ,alba diluted with two ounces of water were placed in a quart bottle1 to which was added a sufficient quantity of the strong spirit of vitriol to let loose all the fixed air from the ,magnesia1 during the separation of which1 another equally putrid piece of beef was suspended in the bottle1 which was so corked as to retard1 though not totally prevent the escape of the air4 ,another piece of the same beef1 was exposed in like manner to the vapour arising from the addition of oil of vitriol to two drachms of chalk diluted with water4 ,they were suffered to remain for twenty two minutes1 and being then examined were absolutely free from any putrid foetor1 and though well washed in water continued quite sweet4 ,,experiment ,,xxxii4 ,air expelled from ,magnesia by the nitrous acid1 sweetened a piece of the same putrid flesh suspended in the neck of the bottle during the effervescence4 ,the beef smelled of the nitrous acid1 but remained equally sweet when washed from it in water4 ,very little change was produced in another piece exposed to the smoaking spirit of nitre4 ,it may be some additional evidence in support of the sweetening properties of fixed air1 to declare that the highly offensive1 sanious discharge of a cancer has been rendered considerably sweeter by itx2 and that ,i have seen a case of a dysenteric fever1 attended with extremely foetid and bloody stools1 in which fixed air was directed1 by the ,physician who attended1 to be thrown into the intestinal tube by way of clyster2 the consequences of which were the correction of the putrid smell of the discharges1 and the reduction of the inflation of the abdomen1 together with contributing considerably to the ease of the patient after each injection of airy4 ,a third case of this kind has very lately occurred to ,dr4 ,percival1 in which the injection of fixed air removed the foetor of the stools1 and the patient recovered without the assistance of any other medicine1 except the moderate use of wine as a cordial1 and of a decoction of ,peruvian bark during the convalescent state4 ,i have also experienced the removal of a very large and deep slough1 and the healing of the ulcer in the putrid sore throat1 more expeditiously by the inspiration of fixed air than by any other method4z x ,directions for impregnating ,water with ,fixed ,air1 by ,joseph ,priestley1 ,l4,l4,d4 ,f4,r4,s4 y ,this case1 together with another similar to it1 will probably appear more fully in the next volume of the ,philosophical ,transactions1 with ,dr4 ,priestley's papers on factitious air4 z ,the patient in this last case being a lady in the country1 at such a distance that ,i could not frequently visit her2 by continuing to inspire the fixed air1 after the ulcer was cleansed1 and in a healing state1 brought on a considerable inflammation of the fauces4 ,one circumstance in the twenty ninth experiment peculiarly attracted my attention1 viz4 that the air in the bottle was so very putrid1 though the beef exposed to it was restored to sweetness4 ,the septic effluvium therefore did not appear to be destroyed1 but to have changed place4 ,from this fact it occurred to me that there might possibly be an affinity between the fixed air and the septic particles1 and that this air might act as a menstruum on the effluvia emitted by putrid bodies4 ,i have since had the pleasure to see that ,dr4 ,priestley1 whose investigation into the nature of factitious air has lately been laid before the ,royal ,society1 and must contribute to exalt him to a still higher rank as a ,philosopher1 has taken notice of something similar hereto4 ,i am sensible that difficulties attend this theory4 ,doctor ,percival1 in the second volume of his ,essays1 which is now in the press1 has offered some ingenious conjectures on the subject1 and to them ,i refer the reader4 ,i shall only mention one experiment which seems to give some force to this doctrine4 ,,experiment ,,xxxiii4 ,slips of linen cloth dipped in very rancid oil1 had their rancidity much diminished by exposure to a stream of fixed air from an effervescent mixture of chalk and spirit of vitriol4 ,but a pint bottle of the same oil being saturated with this vapour1 was equally offensive as before the air was thrown into it1 though the oil appeared to absorb a considerable quantity of air4 ,dr4 ,macbride exposed a piece of rag dipped in lixivium tartari1 and another tinged blue by the scrapings of raddishes1 to the vapour arising from a large vat of melasses wash in high fermentation1 without any change being effected in either1 which could be supposed to proceed from an acid vapour4 ,but as water impregnated with fixed air has evidently an acidulous taste1 and it seemed probable that some of the vitriolic acid might be volatilized during the effervescence which proceeds from its admixture with the alkaline body1 when the air is procured from these substances1 it was apprehended that the antiseptic and sweetening powers of air thus obtained1 might depend on the acid contained in it4 ,in order to evince how far this conjecture was just1 ,doctor ,percival was so obliging to assist me in suggesting and making the following experiments4 ,,experiment ,,xxxiv4 ,twenty drops of syrup of violets mixed with a glass-full of water were changed into a lively red by the addition of one drop of dilute spirit of vitriol4 ,the season of the year did not allow us to use the fresh juices of vegetables1 but this trial shews the genuineness of the syrup of violets1 and that it was a sufficiently delicate test of acidity4 ,,experiment ,,xxxv4 ,a paper besmeared with this syrup1 was placed over a vessel which contained an effervescing mixture of chalk and oil of vitriol4 ,no change of colour took place except in one small pointaa1 which had probably been accidentally touched by the vitriolic acid4 aa ,in making this experiment1 if the vegetable juice be placed too near to the effervescing mixture1 some particles of the acid will be forced up to it1 together with the air1 and may occasion an erroneous conclusion to be drawn from it4 ,,experiment ,,xxxvi4 ,twenty drops of the syrup of violets were added to a glass-full of water strongly impregnated with fixed air1 after the method directed by ,dr4 ,priestleyab1 but without any variation in the colour of the violets4 ab ,directions for impregnating water with fixed air1 c4 by ,joseph ,priestley1 ,l4,l4,d4 ,,experiment ,,xxxvii4 ,a few drachms of the syrup of violets were dissolved in half a pint of water1 which was afterwards impregnated with air from an effervescing mixture of chalk and the smoaking spirit of nitre2 but the syrup of violets suffered no change of colour4 ,,experiment ,,xxxviii4 ,a piece of putrid flesh which had been sweetened by the vapours of iron filings and the nitrous acid1 had a pungent1 acidulous smell4 ,it was carefully washed in water1 and still remained free from putridity4 ,a few drops of lixivium tartari were instilled into this water without producing any sensible effervescence4 ,may we not infer from these experiments1 that if fixed air be an acid1 it is an extremely weak one1 and not sufficient1 as such1 to sweeten putrid bodies2 which effect must consequently be owing to some other mode of action1 the principles of which are not as as yet positively defined8 ,,chap4 ,,xi4 ,a ,,review ,,of ,,the ,,general ,,conclusions ,,deducible ,,from ,,the ,,foregoing ,,observations ,,and ,,experiments4 #a4 ,the due preparation of ,,magnesia ,,alba depends on the proper mixture of the alkaline lixivium with the solution of the sal catharticus amarus2 on the precipitated powder being immediately thrown into a very large quantity of boiling water2 on the purity of the water used in the process2 on the expeditious drying of the medicine1 and on an exact attention to cleanliness4 #b4 ,the artificial ,epsom salt1 or sal catharticus amarus1 affords ,magnesia1 at least1 equally pure with that obtained from the ,epsom waters2 and as the writersac on mineral waters mention those of ,epsom to contain besides their salt1 a considerable quantity of unneutralized earth1 which appears1 from ,dr4 ,rutty's experiments1 to be calcareous1 they should seem peculiarly unfit for the purpose of preparing ,magnesia4 ,some of the ,epsom ,magnesia being calcined1 impregnated distilled water with a calcareous earth4 ac ,allen1 ,lucas1 ,rutty1 ,monro1 c4 #c4 ,a sufficiently strong and well purified lixivium of potashes is equally adapted to procure the precipitation of ,magnesia1 as a ley made with salt of tartar1 or any other fixed alkali4 #d4 ,,magnesia ,,alba differs essentially in its chemical and medicinal properties from every other known absorbent earth2 and when mixed with an acid1 either before or after its admission into the stomach1 is purgative in a much smaller quantity than chalk1 crab's eyes1 or any of the calcareous or testaceous earths4 #e4 ,the calcination of ,magnesia divests it of those disagreeable properties complained of by ,hoffman1 and other practitioners2 the fixed air which constitutes so great a share of its composition1 and is the cause of the uneasy sensation produced by this powder1 being expelled in the process4 ,but depriving the ,magnesia of its air does not render it caustic or unfit for internal uses4 #f4 ,it is a common1 but unchemical practice1 to mix acid and alkaline substances in the same composition1 without attending to the changes which will be produced in their nature by being united4 ,among other instances of this kind which might be pointed out1 we often meet with lenitive electuary1 cream of tartar and ,magnesia ,alba prescribed together in one medicine1 the consequence of which is1 that the ,magnesia is not only unintentionally neutralized1 but the effervescence produced in it by the acid occasions the electuary to swell and renders it unsightly1 besides altering the nature of the pulps and syrup which enter the composition1 by inducing a vinous fermentation in them4 ,the calcined ,magnesia being a non-effervescent may be united with acids under this form without any other inconvenience than their producing a neutral salt1 and the propriety of this change must depend on the intention of the prescriber4 #g4 ,it appears that ,magnesia ,alba1 though remarkably septic to animal flesh1 retards the putrefaction of bile1 and restores sweetness to it when actually putrid3 ,that these last effects are still more strongly produced by the calcined ,magnesia1 which also powerfully resists the corruption of flesh3 ,that some of the other absorbents prove antiseptic to bile2 and consequently that the opinion of the universal septic property of the absorbent class of medicines1 and of the impropriety of prescribing them in bilious diseases1 may admit of some exceptions4 #h4 ,magnesia1 when calcined1 has the same property as quick-lime of promoting the solution of resinous gums in water4 #i4 ,the increased power of water as a menstruum to vegetable astringents1 depends on only such a quantity of lime being employed as can be saturated with air by the solvend2 but if a larger proportion be used1 the action of the water on the vegetable is rather prevented than promoted4 #aj4 ,though lime water in several instances appears to be a more powerful menstruum to vegetables than distilled water2 yet the latter is sometimes preferable1 and acts more efficaciously than when impregnated with lime4 #aa4 ,antiseptic vegetables yield tinctures to lime water1 which resist putrefaction more powerfully than those prepared from the same drugs with distilled water1 without lessening the cohesion of animal fibres4 #ab4 ,waters which contain a large quantity of calcareous earth1 either simply suspended1 or in a neutralized state1 are highly improper for pharmaceutical purposes in general1 and especially for the preparation of extracts1 where much water and long continued boiling are requisite4 #ac4 ,the power of fixed air to restore sweetness to putrid bodies1 is1 it is hoped1 clearly established3 and there appears to be some degree of probability1 that fixed air produces this effect by acting as a menstruum to the putrid effluvia3 ,it seems also to be proved1 that its antiseptic quality is not owing to any acidity which it carries off with it from the effervescing mixture4 ,,the ,,end4 ,illustration3 ,decorative ,band ,,an ,,appendix ,,to ,experiments and ,observations ,on the ,,preparation of ,,magnesia1 c4 ,,containing ,strictures on ,mr4 ,,glass',s ,,magnesia4 ,by ,,thomas ,,henry1 ,apothecary4 ,manchester1 ,march #h1 #aggc4 ,,it is with the utmost reluctance ,i find myself indispensibly obliged to address the public on a subject1 from the nature of which ,i may perhaps incur the suspicion of acting from interested views3 should ,i be so unhappy1 my friends who know me will1 ,i trust1 do me the justice to acquit me of the charge of being influenced by any improper motives2 and ,i shall hope for the candid indulgence of those persons to whom ,i am a stranger4 ,about a year and half since ,i transmitted to the ,college of ,physicians an account of a method of preparing ,magnesia ,alba1 equal to that which had been long sold by ,mr4 ,glass of ,oxford1 and which was generally and deservedly esteemed by others1 as well as by myself1 to be the standard of purity4 ,though that gentleman carefully concealed the minuti on which the success of his process depended1 he had always prepared it with the most laudable attention4 ,my process was received by the ,college1 and published in the second volume of the ,transactions of that truly respectable society1 and has since been reprinted in a pamphlet which ,i lately published1 and in which1 among other subjects1 ,i have recommended ,calcined ,magnesia to the attention of the faculty1 as a medicine of considerable importance4 ,notwithstanding ,i had been informed1 by a relation of ,mr4 ,glass1 that he had disposed of his name in the ,magnesia business to some persons1 for a very valuable consideration1 yet ,i doubted not their adhering to the proper manner of preparing it2 but as ,i have since had occasion to change my opinion1 and as the credit of the ,calcined ,magnesia depends so much on its purity before calcination1 ,i am necessitated to take this method of informing the public of my reasons for declaring that sold under the name of ,mr4 ,glass to be impure1 calcareous1 and improper for the purpose of calcining4 ,two or three years had elapsed since ,i had seen any of ,mr4 ,glass's ,magnesia1 except a small quantity which ,i had preserved1 as a standard for the levity of what ,i prepared myself4 ,but having a mind to calcine some of his1 in order to compare it with my own1 ,i sent for a box from ,mr4 ,harrop1 an agent of the proprietors in this town4 ,i was surprized1 on opening if1 to find the ,magnesia specifically lighter1 to an amazing degree1 than any ,i had formerly seen1 insomuch that the six shillings box1 which used to contain about four ounces1 now only contained an ounce and half1 ,troy weight3 so that this medicine is sold at the rate of two pounds eight shillings the ,troy pound1 which is not fourteen ounces ,avoirdupois4 ,on attempting to dissolve it in the vitriolic acid1 ,i found the solution very imperfect2 and on calcining half of the contents of the box1 it was with indignation that ,i discovered this ,magnesia1 so extolled1 so puffed in every newspaper1 for its superior purity and goodness1 to contain no inconsiderable quantity of calcareous earth2 for the pungency of it was very disagreeable in the mouth1 and one scruple of it impregnated an ounce of water almost as strongly as so much lime would have done4 ,these are tests1 which1 tho' much stronger than that of levity which the proprietors have artfully placed as the principal one1 they have avoided mentioning1 being sensible of its deficient solubility1 and that it would not stand the ,,fiery ,,ordeal4 ,willing1 however1 to believe that this impurity might be accidental1 though ,i had reason to think1 from the artful conduct above alluded to1 that it was not so1 ,i sent for a box of ,magnesia1 from the agent for the sale of ,mr4 ,glass's ,magnesia at ,preston4 ,this likewise proved calcareous1 though ,i thought the lime1 produced by calcining it1 not quite so pungent as the other2 it1 however1 made a strong lime-water4 ,that ,i might avoid drawing too hasty conclusions1 ,i procured a third box from ,chester1 which being subjected to the same trials1 seemed more impure than either of the other two4 ,this ,magnesia formed a very imperfect solution in the vitriolic acid2 and the taste of the lime1 after calcination1 was so very disagreeable1 that ,i was not free from it for some hours4 ,the water impregnated with it was as strong to the taste as common lime-water1 and the precipitate which fell from it1 on blowing air into it1 was as copious as ,i ever observed from that prepared with stone or oyster-shell lime4 ,the boxes were all purchased from the agents for the sale of ,glass's ,magnesia1 and every box was sealed with his arms1 and had every other mark of authenticity4 ,i have retained samples of each in both states4 ,i have since repeated the above experiments on the contents of two boxes of ,glass's ,magnesia1 the one of which was purchased of ,mr4 ,r4 ,davis1 in ,sackville-street1 ,piccadilly1 the other of ,mr4 ,william ,nicoll1 in ,st4 ,paul's ,church-yard4 ,the ,magnesia in each proved to be calcareous1 and acquired the properties of quick-lime by calcination4 ,it would be natural for every person1 who might wish to give the ,calcined ,magnesia a fair trial1 to obtain ,mr4 ,glass's for that purpose1 on the supposition of its being superior to any other2 and as the very first taste of it1 in that state1 would be sufficient to prejudice any one against the farther use of it1 ,i am necessitated1 in justice to my own reputation1 and to the public1 who may otherwise be deprived of a very valuable medicine1 to enter this protest against the use of it4 ,i have fairly and candidly given up to the public what ,i have found to be the best method of preparing ,magnesia1 sufficiently pure for every medical and chemical purpose2 and ,i sincerely wish that every apothecary1 who has opportunity and leisure1 would prepare it himself4 ,but as1 from various reasons1 there are1 ,i am convinced1 too many who omit to do it1 and that too little attention is paid to examining into the purity of what is used2 and as it also appears the public have been imposed on1 where they had reason to think themselves most secure1 ,i have sent to ,mr4 ,,johnson1 ,no4 #gb1 ,st4 ,paul's ,church-yard1 and ,mr4 ,,ridley in ,st4 ,james's-street1 a quantity of ,magnesia1 both in a calcined and uncalcined state1 which1 though not ,,equal ,,in ,,levity1 nor quite so costly1 even when calcined1 as that sold as ,mr4 ,glass's1 will1 ,i doubt not1 prove to be non-calcareous1 and superior to it in every other respect4 ,and if it should appear so to the gentlemen of the faculty1 ,i wish for no preference to those apothecaries who prepare the medicine faithfully2 but flatter myself that ,i have a superior title to the favour of physicians1 of my brethren1 and of the community1 than those persons can claim1 who have meanly stooped to secrete a process1 the knowledge of which must be beneficial to mankind1 and have abused the public confidence4 ,i shall only add1 that so far was ,i from expecting to find ,mr4 ,glass's ,magnesia impure1 that ,i bought it as a standard2 that1 as ,i am informed that ,gentleman is dead since this inquiry was finished1 nothing1 less than the reasons ,i have adduced1 could have prevailed on me to have published this ,appendix at this season2 and that ,i do not consider him1 but the present preparers of the ,medicine1 as culpable for the adulteration4 ,that ,i have been favoured with an account of some experiments made by a ,physician of considerable eminence1 on that ,magnesia1 the result of which was similar to what ,i have here recited2 and ,i appeal for proof of the truth of what ,i have asserted1 to every reputable person who may now have any of it in his possession1 and will make the experiment2 and that having rested my cause on that issue1 ,i mean not to enter into any controversy on the subject4 ,n4 ,b4 ,calcareous ,magnesia is neither so absorbent1 nor so purgative as the pure4 ,,finis4 99 99 99 99 99 ,transcriber's ,notes ,obvious typographical errors have been corrected1 but variations in spelling1 punctuation and hyphenation have been retained4 ,in particular1 the phrase head achs in ,chapter ,,iii4 has been retained4 ,experiment ,i was erroneously numbered ,,ii4 ,this has been corrected4 ,footnote identifiers are italic in the book4 ,the italic markers have been omitted for the sake of clarity4 ,the reference to ,,an ,,appendix has been added to the ,table of ,contents4 ,the ,errata listed have been corrected in the text4 ,italics are shown thus italic4