,illustration ,,collotype ,,and ,,photo-,,lithography ,,practically ,,elaborated ,,by ,,dr4 ,,julius ,,schnauss1 ,member of the ,imperial ,german ,academy of ,naturalists1 c4 ,,translated1 ,,with ,,the ,,author',s ,,sanction ,,and ,,assistance1 ,,by ,,edwin ,c4 ,,middleton4 ,,together ,,with ,,an ,,appendix ,,on ,,steam ,,presses1 ,,by ,,the ,,translator4 ,,london3 ,,iliffe ,,and ,,son1 #c1 ,,st4 ,,bride ,,street1 ,,ludgate ,,circus1 #ahhi4 ,,printed ,,by ,,iliffe ,,and ,,son1 #c1 ,,st4 ,,bride ,,street1 ,,ludgate ,,circus1 ,,london1 ,e4,c4 ,,works3 ,,coventry4 ,,contents4 ,,chapter4 ,,page4 ,i4 ,introductory #i ,,ii4 ,bichromates in ,conjunction with ,organic ,substances #ab ,,iii4 ,summary of the more important ,printing ,processes with ,chromated ,gelatine #ah ,,iv4 ,collotype ,apparatus #be ,v4 ,chemicals and ,materials for ,collotype #df ,,vi4 ,preparation of the ,collotype ,plate #ei ,,vii4 ,negatives suitable for ,collotype #gb ,,viii4 ,printing in the ,press #hh ,,ix4 ,finishing and ,varnishing ,collotype ,prints #if ,x4 ,other ,collotype ,processes #ajb ,,xi4 ,failures in ,collotype3 ,in the ,preparation of the ,plates #ajg ,,xii4 ,investigations on ,collotype #aad ,,xiii4 ,collotype in ,natural ,colours #aai ,,xiv4 ,magic ,prints #abb ,,xv4 ,photo 8,glass0 ,printing #abd ,,xvi4 ,allgeyer's ,collotype ,process #abg ,,xvii4 ,practice of ,photo-,lithography #acj ,,xviii4 ,autography #ace ,,xix4 ,negatives for ,photo-,lithography #adi ,,xx4 ,application of the ,carbon ,process to ,photo-,lithography #aee ,,appendix4 ,steam ,presses #afb ,,translator',s ,,preface4 ,the impossibility of obtaining any work in the ,english language on the subject of ,collotype first led to my translation of the ,german work of ,dr4 ,schnauss1 and the fact that no work has hitherto appeared fully dealing with the matter is the excuse ,i offer for the present publication4 ,the translation is necessarily one of considerable freedom1 but it is offered as containing all the information to be found in the original1 and in addition1 considerable extensions1 made with the author's consent4 ,the omission of the chapter dealing at length with the steam machine was necessitated by the fact that the rotary machine there described is no longer manufactured4 ,without pointing to the frontispiece in any sense as a high-class work1 it may serve to show that ,i have made some practical acquaintance with the subject4 ,the illustration1 printed on ordinary paper1 was produced from the instructions found in this work1 and ,i may add that at the time of writing ,i have printed over #ejj impressions from the first plate1 and it still remains in fair working condition4 ,,edwin ,c4 ,,middleton4 ,,stanmore ,,road1 ,,birmingham4 ,,collotype ,,and ,,photo-,,lithography4 ,,chapter ,i4 ,,introductory4 ,the observation by ,mungo ,ponton of the sensitiveness to light of bichromate of potassium in conjunction with organic substances is but little more recent than the discovery of photography itself4 ,if sized paper is saturated with an aqueous solution of this salt and then exposed under any transparent design1 the latter will be reproduced as a negative of a brown colour on a yellow ground4 ,if the exposed paper is placed in water1 the bichromate salt will be removed from the unexposed1 and consequently unaltered portions2 the image will remain brown after this treatment1 though somewhat bleached4 ,the sensitiveness to light is proportionately increased by the addition of larger quantities of organic substances1 as starch1 paste1 glue1 sugar or gum1 as first observed by ,becquerel4 ,this arises in consequence of the organic matter being oxidised by the chromic acid1 a corresponding decomposition and reduction of the chromate salt to chromate of chromium taking place4 ,in the year #ahec an ,englishman--,fox-,talbot1 the gifted discoverer of calotype 7i4e41 the production of photographic negatives on paper by means of silver salts7--followed up the lines of these important observations1 and discovered that the mixture of bichromate of potassium and glue entirely lost its solubility and power of swelling in cold water after exposure to light1 and on this he based his process 7heliography7 of etching on metal plates4 ,the plate1 after receiving a coating of the chromated gelatine solution1 was dried1 exposed under a positive1 and afterwards developed or washed out in warm water1 all unexposed and consequently soluble portions being removed1 while the exposed and therefore insoluble portions covered as a negative,a the metal plate1 and so protected it in those parts from the etching mordant employed1 usually chloride of potassium or perchloride of iron4 ,his successor in these researches was a ,frenchman1 ,poitevin1 who invested these processes with even greater practical importance4 ,he1 however1 worked chiefly on paper with the bichromate mixed with albumen or gelatine1 and attained results which were the first practical steps towards photo-lithography and carbon or pigment printing4 ,further on we shall return with more detail to these subjects4 ,in the hands of ,tessi du ,motay and ,marechal1 of ,metz1 the discoveries of ,poitevin derived further practical value1 and to them we are indebted for the first advances in collotype1 they in their practice using metal plates as a support4 ,joseph ,albert1 of ,munich1 followed1 and introduced further and considerable modifications1 amongst others utilising glass plates as a foundation4 ,the want of adhesiveness of the chromated gelatine layer to its support was a source of great trouble to the earlier experimentalists1 and was a matter giving rise to innumerable difficulties1 which were1 however1 finally surmounted by the researches of ,husnik1 ,albert1 and ,obernetter4 ,a ,for the production of an intaglio plate the impression on the chromated gelatine must be printed from a positive1 which will naturally give a negative on the copper plate4 ,,chapter ,,ii4 ,,the ,,bichromates ,,in ,,conjunction ,,with ,,organic ,,substances4 ,chromic ,acid1 now usually known as chromium-trioxide--,cr,o#c--;is found in beautiful red needles1 which are slightly deliquescent4 ,according to the present accepted theory1 water containing such crystals in solution contains the true chromic acid1 ,h#b;,cr,o#d1 which cannot be produced as crystals4 ,both the crystals and a concentrated solution in water give up with facility a part of their oxygen1 sometimes with explosions accompanied by the appearance of fire1 and green chromium oxide1 now called sesquioxide1 ,cr#b,o#c1 is formed4 ,bichromates of alkalies act in a similar manner1 but in a lesser degree4 ,if1 for instance1 a few drops of sulphuric acid be added to a solution of potassium bichromate1 and then a little alcohol1 or1 instead of that1 a piece of sugar be added and moderate heat applied1 the solution will be violently agitated1 its yellow-red colour will disappear1 the bichromate be decomposed1 and chromium oxide be formed1 which1 combining with the sulphuric acid1 forms a solution of a violet green colour4 ,if a sufficient quantity of sulphuric acid be present1 the chromium sulphate and the potassium sulphate combine1 forming chrome alum crystals1 octahedron in form1 similar to those of ordinary alum1 but of a beautiful dark violet colour4 ,the same are used in both the carbon and collotype processes4 ,bichromate of ammonium is easily decomposed by fire by heating it in a dry state4 ,it will be understood that in consequence of the decomposition1 or rather reduction1 of chromic acid by organic matter1 the latter is also decomposed and oxidised in a corresponding degree4 ,the agent producing this effect may be either heat or light1 or both together2 but of special interest to the collotypist is the action of light upon different combinations of chromic acid1 in the shape of alkali bichromates in conjunction with organic matters4 ,glue or ,gelatine1 in a solution containing about five per cent4 of one of the bichromates spread upon glass plates1 and exposed to light1 will1 where exposed1 become dark brown1 at the same time become insoluble in water1 and also lose its power of absorbing the same4 ,according to the researches of ,dr4 ,eder1 this brown substance consists of chromium chromate and unaltered gelatine4 ,the oxidised portion of the latter remains soluble and may be entirely removed by treating with warm water4 ,during the exposure to light formic acid is undoubtedly formed4 ,ammonium bichromate1 with gelatine1 is in the dry state much more sensitive than the potassium salt2 it also decomposes more readily when heated in the gelatine solution1 a matter which must not be lost sight of in the preparation of the collotype plate4 ,isinglass--a tolerably pure glutin4 ,in conjunction with the bichromates it presents the same characteristics as gelatine4 ,albumen1 when mixed with a solution of a bichromate1 is not thereby coagulated1 as occurs upon the addition of pure chromic acid4 ,if poured upon glass and dried it also becomes insoluble in water after a sufficient exposure to light4 ,this solution is used with great advantage in photo-lithography1 as the unexposed parts are readily soluble in cold water4 ,the older method1 which consisted of using gelatine in conjunction with bichromate1 rendered hot water necessary in the development of the fatty ink image upon the transfer paper1 and as a consequence of the rubbing at times necessary1 the ink1 already softened by the warm water1 became smeared1 the resulting image considerably impaired1 and the transfer thereby rendered altogether useless4 ,in collotype a bichromated albumen substratum is still used by many operators1 this coating when dry being exposed through the glass plate1 the latter placed coated side downwards upon a flat black support1 preferably of velvet4 ,after this exposure the gelatine layer--from which the prints are produced--is applied4 ,this method was first published by ,albert1 who originated it4 ,the chromated albumen solution will not keep long even in the dark1,b as the albumen coagulates1 and on this account photo-lithographic papers coated with this solution must be used within a few hours of their preparation4 ,such papers are now conveniently prepared with the albumen1,c and sensitised as required by floating upon an aqueous solution of one of the bichromates1 to which has been added twenty-five per cent4 of methylated spirit4 ,b ,i have found this solution keep a considerable time--a month at least4--,,trans4 ,c ,i believe ,husnik has now discontinued to prepare his photo-litho transfer paper with an albumen coating4 ,recent issues of his paper have been simply coated with gelatine4--,,trans4 ,the chromated gelatine used in collotype may be kept as a jelly in the dark room1 but is better prepared fresh4 ,of carbon hydrates only gum chromate is of interest to the collotypist1 its employment being restricted to the 8dusting on0 process1 and the occasional addition of titles1 c41 to the otherwise finished plate4 ,as with all mixtures of the bichromates and organic substances1 it is only sensitive to light when in a dry condition1 and solutions of it may1 without harm1 be exposed for some time to diffused daylight4 ,aqueous solutions of gum arabic soon become sour and mouldy1 and in this condition are useless for the 8dusting on10 or1 in fact1 any other photographic process4 ,as a preventive a few grains of sulphate of quinine may be added1 which will preserve it effectually1 and is quite inert in photographic operations4 ,this solution applied to glass and dried is1 in its dry condition1 extremely sensitive to light4 ,if printed under a negative1 and then exposed to a damp atmosphere1 it absorbs moisture1 and becomes 8tacky0 upon the portions fully protected by the densest portions of the negative1 while the parts exposed under the clear glass of the negative will be free from any such tendency4 ,the gradations of the negative between these two extremes will be represented by the surface of the gum being more or less adhesive1 and it is this property which renders it valuable in various processes4 ,after exposure under a negative finely-ground colour--for instance1 graphite--is carefully dusted over the surface of the plate by means of a camel-hair brush1 and the powder will adhere in exact proportion to the protection afforded by the negative4 ,a picture is thus produced in graphite powder possessing all the gradations of the original4 ,from a negative a second negative is produced1 while from an exposure under a positive a positive will result1 each1 however1 reversed as regards left and right when compared with the original4 ,advantage is taken of this process to produce reversed negatives1 a subject more fully dealt with in another chapter4 ,bichromate and ,sugar are never used alone1 but as an addition to heighten the sensitiveness and increase the hygroscopic properties of the gelatine or gum-chromate solutions4 ,by the addition of sugar and a little ammonia to chromated gelatine the solubility of the gelatine in hot water is increased4 ,the addition of acetic acid instead of ammonia acts in a contrary direction4 ,it is advisable to become acquainted with the action of certain substances1 the application of which to the printed layer increases its solubility after exposure to light1 and of others having a contrary or hardening influence on the same1 such oft-times proving of service in the case of under or over exposure4 ,to the former class belong all alkalies1 as chloride of lime and cyanide of potassium2 while among the latter1 which have a tanning or hardening effect on gelatine1 may be particularly mentioned tannin1 alum1 chrome alum1 and chloride of zinc4 ,to remove spots1 which print dark1 from collotype plates a solution of chloride of lime is used4 ,to produce dark spots without exposure to light a solution of tannin is used1 which is also available for adding descriptive titles or other matter to the plates4 ,the ink will 8take0 as well on the spots or parts touched with the tannin solution as if exposed to light4 ,a collotype plate which has been prepared for printing from may also have writing executed upon it with a bichromated gum solution1 once more exposed to light1 the writing will then readily take the ink1 and appear in the impression as a black inscription4 ,gum chromated solutions reduced to proper proportions1 and applied to different textures and the same subsequently exposed to the light1 render them completely waterproof4 ,,chapter ,,iii4 ,,summary ,,of ,,the ,,more ,,important ,,printing ,,processes ,,with ,,chromated ,,gelatine4 ,these processes are all based upon the change in the hygroscopic properties of chromated gelatine brought about by the action of light1 which renders the parts exposed insoluble4 ,carbon or ,pigment ,printing4--,in this interesting process finely ground colouring matter is added to the solution of chromated gelatine1 and spread upon paper2 or the paper may be coated with the gelatine and pigment1 and afterwards excited by immersion in a solution or bath of one of the bichromates4 ,if1 after drying such paper or tissue1 it be exposed under a negative in an ordinary printing frame1 and then immersed in warm water 7#ij to #acj ,f471 the water will dissolve only such portions as may not have been affected or hardened by the action of light through the negative1 while the parts that have been exposed to its action will be insoluble1 and remain attached to the paper support1 forming a positive picture4 ,images produced in such a manner1 however1 are devoid of half-tone1 and this procedure is only suitable for line subjects1 while even for such the paper must have been very evenly coated1 or portions of the picture may be washed away4 ,for the production of half-tone subjects it is necessary that the picture be developed from the back4 ,this may be effected by transferring the printed tissue1 after first soaking in cold water1 to a surface1 usually either of paper or glass1 and developing it in contact with1 and allowing it to remain upon1 such surface4 ,this procedure is known in carbon printing as single transfer4 ,unless the negative be a reversed one--or a film printed from the reverse side--the resulting print will be subject to the disadvantage of being reversed as regards left and right4 ,in cases where ordinary negatives have to be used1 and this reversal cannot be tolerated1 it is overcome by the 8double transfer0 method of printing1 the print in such cases being developed upon a so-called 8temporary support10 and again transferred to its 8final support10 when it appears as a non-reversed image in permanent pigment4,d ,d ,for further details of this interesting process see the 8,autotype ,manual10 by ,j4 ,r4 ,sawyer2 or ,liesegang's 8,carbon ,process40 ,the 8,powder0 ,process4--,take1 instead of gelatine1 a solution of gum arabic and sugar1 to which is added a solution of bichromate of potassium or ammonium4 ,with this a glass plate is coated1 dried1 and exposed under a negative1 if it be desired to produce a negative2 or1 if a positive be desired1 the exposure must be made under a positive4 ,after a short exposure the plate is dusted over with a powder in an extremely fine state of division1 such as graphite if for negatives2 if for burnt-in enamels1 a specially-prepared enamel1 ground extremely fine1 must be used4 ,such powders will only adhere to the plate in exact proportion to the action of the light during the exposure in the printing frame1 and a reversed copy of the original will be produced4 ,collotype and ,glasstype4,e--,in these processes the printing depends upon the property possessed by the bichromated gelatine film1 which has been properly exposed under a negative1 of absorbing water in varying proportions1 in exact accord with1 but in inverse ratio to1 the action of the light4 ,the application of a roller charged with fatty ink of a suitable consistency1 will deposit upon the gelatine surface a layer of ink in exact proportion to the action of the light and in inverse proportion to the amount of water absorbed by the film4 ,in this manner a picture is produced in ink which by printing is transferred to paper1 and will exhibit all--even the finest--gradations of light and shade4 ,e ,glasstype1 more fully described later on1 has never been practised commercially in ,england4 ,woodburytype4--,if an especially thick film of gelatine1 containing a small proportion of pigment1 be sensitised1 exposed under a negative1 and subjected to prolonged soaking in warm water1 a picture exhibiting considerable relief will be obtained1 which1 after drying1 may1 by pressing into lead or treated by the galvanoplastic method1 yield a matrix from which casts may be produced in a coloured gelatine solution1 or ink1 which is poured into the mould2 on this is placed a waterproof paper2 the press1 which is of special construction1 is closed1 and the ink allowed to set2 the paper is then removed1 bearing upon its surface the printed ,woodburytype1 which is hardened by alum1 and then scarcely distinguishable from a silver print4 ,stannotype is a modification of the last-described process by the same inventor4 ,a positive is first produced from the original negative1 and from the positive a print is made on a thick gelatine tissue4 ,this is developed by long washing in warm water1 the resulting relief being a negative2 this is coated with tinfoil of extreme thinness1 and used as a mould for printing from with the gelatine ink1 as previously described4 ,this obviates the use of hydraulic pressure and special and expensive appliances4 ,heliogravure2 ,photogravure4--,if1 instead of printing from the ,woodbury mould in the gelatinous solution1 a fatty ink is used1 the process is known under these titles4 ,the exact methods of roughing the depths of the plates to facilitate their retention of the ink are regarded as secrets by the most successful operators4 ,photo-,lithography and ,photo-,zincography4--,in dealing with a subject in lines1 dots1 or stipple1 a paper may be coated with a solution of chromated gelatine1 dried1 exposed under a suitable negative1 coated with a film of fatty ink1 and allowed to soak in cold or tepid water2 this1 penetrating the unhardened portions of the film1 causes them readily to part with the ink1 which1 however1 adheres tenaciously upon the hardened portions1 representing the picture4 ,this image1 when properly cleared1 may be transferred to stone or zinc1 and printed from in the lithographic manner upon a suitable press1 or if the image upon the zinc be etched into relief by the process known as ,gillotage1 and mounted on a wood block of suitable height1 it presents a printing surface which may be used in conjunction with type4 ,gelatinotype4--,it has long been felt as a desideratum to make use of the photogenic properties of the gelatino-bichromate for letterpress printing1 i4e41 to find out a simple and satisfactory method by which collotype plates could be transformed in letterpress printing plates4 ,there have been made many attempts in this direction1 but hitherto without any practical results2 the difficulties seemed to be too great4 ,recently1 however1 ,professor ,j4 ,husnik1 of ,prague1 has overcome these difficulties1 his new patented process1 called by him 8,leimtypie10 that is to say1 ,gelatinotype1 being one of the greatest practical value1 quick1 cheap1 and giving most satisfactory results4 ,the process consists in the production of high relief blocks in gelatine4 ,husnik exposes a gelatino-bichromate tissue under a negative1 and then develops the relief picture in a peculiar manner4 ,the method consists in the application of a saturated solution of bichromate salts for developing1 a new and previously unknown property of the chrome salts thus coming into employment4 ,these salts1 in comparison with the acids1 have the advantage not only of dissolving all unexposed gelatine during development1 but also in hardening the already exposed parts of the picture upon the copy to be developed1 the impression received from the light being increased by contact with the chrome salt solutions4 ,in this way the relief can be developed a longer time1 and becomes deeper4 ,another new phase is the manner of the second development4 ,the first development is interrupted before the fine parts have been injured1 the relief allowed to dry1 the white parts 7the sub-ground7 covered with printing ink diluted with turpentine1 using a fine brush quite near to the lines1 and then the whole relief exposed once more to light4 ,the relief1 on account of its having taken up much chrome salt during the first development1 is very sensitive to light1 and hardens not only on the surface1 but also on the sides of the lines4 ,after removal of the black ink it can be developed to any depth1 particularly if the larger white parts have before been cut out with a knife4 ,this process has lately been further improved by the inventor1 by the use of gutta-percha films1 which are placed between the gelatine film and the zinc plate on which the gelatine relief has to be fastened4 ,this is effected as follows3--,the zinc plate1 after having been well cleaned and rubbed over with emery paper1 is coated with a gutta-percha solution and dried4 ,it is then heated to about #bab ,f41 and allowed to cool4 ,during this cooling process the bichromated gelatine film1 before being developed1 is laid on at a temperature of between #aaa and #gg ,f41 whereby the hardening gutta-percha film secures a perfect combination with the zinc plate4 ,when this has been done the gelatine film is developed in the above described manner to a relief4 ,by this improvement the gelatine blocks become so solid that they will yield more than #ej1jjj prints in the printing machine without being injured4 ,,chapter ,,iv4 ,,collotype4--,,apparatus4 ,before commencing any practical work it will1 of course1 be necessary to procure various utensils and material not usually found in the photographic studio4 ,all these should be procured from reliable dealers and of the best quality1 for the evil consequences of false economy will make themselves felt in endless failures4 ,the best to be obtained are none too good for collotype4 ,in the practice of photography the whole success depends on a series of apparent trifles1 and the same may be said to hold good1 but in a far greater degree1 in this process1 which is one in which the difficulties can scarcely be overestimated4 ,the photographer will most likely be already in possession of many pieces of apparatus he may utilise--for instance1 dishes4 ,the best and dearest are those of china2 but for many--in fact1 most--collotype purposes1 those of tin or zinc may be used4 ,for warming or cooking the gelatine solutions tin vessels are the handiest1 as they easily conduct the heat and are unbreakable4 ,although the chromated gelatine may remain in them for a short period without harm1 it is not advisable to allow it to do so for any length of time1 but to remove the solution and wash the vessel thoroughly with hot water1 and at once carefully dry1 otherwise they will soon corrode1 and contaminate the gelatine solutions4 ,the best utensils to use are wide-mouthed shallow jugs1 as they are easily kept clean1 and in them the chromated gelatine solution keeps well1 and with their use no fear of decomposition need be entertained4 ,filtering the gelatine solutions is a somewhat troublesome matter1 and should be effected at a high temperature and as quickly as possible4 ,the simplest method is to procure a piece of perfectly clean flannel of suitable size1 thoroughly moisten it1 and insert into a brass ring1 which is provided on the outside with small barbel hooks1 to which the flannel is fixed1 as in the retinaculum of the chemist4 ,the ring is provided with a clip and handle1 by the former of which it may be attached to a vessel of almost any size1 and the latter is a convenience in holding it over plates to which the gelatine has to be applied4 ,a careful filtering is obviously essential to the production of clean plates4 ,many complicated filtering appliances have been devised for gelatine and other solutions difficult of filtration1 as1 for instance1 those of albumen or gum4 ,baron ,szretter describes in the 8,photographische ,correspondenz10 #ahgh1 an apparatus constructed by him4 ,it consists of two vessels1 an upper and a lower one1 which by means of longer or shorter tubes communicate with each other in accordance to the stronger or weaker pressure required by the liquid to be filtered4 ,soldered round the upper rim of the lower vessel is a ring of sheet brass1 about two to three cm4 in width2 over this ring the filter paper is placed1 which again is covered with a piece of strong felt enveloped in flannel4 ,to prevent the liquid escaping round the sides of the ring a strong iron ring is applied1 which by means of a screw presses against the felt so that no space exists between the ring and the paper4 ,to prevent the pressure of the liquid forcing the felt out of position1 and so tearing the paper1 a metal wire gauge is used to keep the felt in place4 ,the liquid placed in the upper vessel passes through the tube into the lower vessel through the paper and felt layer4 ,when it is necessary to warm the solution to be filtered1 as in the case of gelatine1 the whole apparatus is covered with an outer covering1 and on the other side a pipe is applied for the purpose of effecting a circulation of the heated liquid1 which is thus kept constantly rising through the one pipe and returning through the other4,f ,heat is sustained at an even temperature during the whole operation by means of a small lamp4 ,a simple method of filtering such solutions is to pass them through purified sheep's wool1 or spun glass1 a quantity of which is placed in the tube of the funnel4 ,the whole apparatus may be placed in a warm oven during the process1 or the drying box may be utilised for the purpose4 ,f ,illustration3 ,fig4 #a4 ,the above description not perhaps being perfectly clear1 and having been unable to obtain any further description1 ,i give a sketch 7,fig4 #a47 of an apparatus found to answer well for the filtration of gelatine solutions and other viscid bodies4 ,a is a glass flask1 ,b a rubber stopper1 ,c a funnel containing a filtering medium of washleather1 ,d a tube attached to a three-way cock ,e2 one hand manipulates the latter1 while the other works the piston ,f of a syringe ,g4--,,trans4 ,printing ,frames of different sizes will be found to hand in the photographic studio1 and may be utilised without alteration for printing the collotype plates1 if they are deep and strong enough to bear the necessary pressure1 which is usually applied through the medium of springs2 these are better removed1 and wooden wedges inserted in their stead between the cross-bars and the loose wooden back of the frames1 as by these means far more pressure may be applied4 ,by lifting the one half of the hinged back of the printing frame an examination by transmitted light of the collotype plate may be made and an experienced operator will in this manner judge the exposure of the plate4 ,the ,actinometer is1 however1 recommended1 particularly for a beginner1 as it greatly aids in forming a correct idea of the exposure4 ,the ,drying ,box is of great importance to the successful working of the process4 ,the opinions of the various practitioners with regard to the temperature at which the drying of the plates should be effected differ as widely as upon the advisability or otherwise of admitting a current of air through the box during the operation4 ,the drying should be completed as rapidly as possible from the commencement of the operation1 care being taken that the heat never exceeds #ej;,c4 ,many plate-makers simply dry the plates in an open apartment--of course1 only illuminated by a non-actinic light--simply placing the plates on a horizontal surface1 which may be maintained at the temperature indicated by a water bath1 a lithographic stone1 or merely a cast-iron plate arranged in a suitable manner for heating from below4 ,this method of drying is open to many objections3 the surface of the plate is seldom free from dust1 and the gelatine coating is too liable to irregularities from draughts admitted to the apartment during the process4 ,they are more frequently dried in specially-constructed boxes provided with screws for accurately levelling the plates1 and through which only a small circulation of air takes place4 ,these boxes are usually rectangular in shape1 the upright sides being of wood and the bottom of sheet iron4 ,the lid is an open framework covered with a close orange or black cotton material1 the whole standing upon four iron legs over a spirit or gas flame4 ,in the upper part of the box a thermometer is fixed1 about the centre of either the side or lid1 in such a position that it may be readily observed without the necessity of opening the box4 ,strong horizontal iron bars are placed across at about the centre1 and are provided with thumbscrews1 upon which may be placed a plate of glass bearing a circular spirit level1 by which means the plates may be levelled with the greatest accuracy4 ,the sheet-iron bottom of the box being heated unevenly1 it becomes necessary to mitigate this inconvenience as far as possible1 which is easily done by covering the plate to a depth of about half-an-inch with dry river sand1 over which should be placed tissue paper to keep down any possible dust4 ,illustration3 ,fig4 #b4 ,an ,automatic ,regulator of practical value is that devised by ,ruegheimer4 ,it consists of a glass tube1 ,a1 ,a1 ,a4 ,a is closed with an indiarubber stopper1 through which passes a glass tube ,b1 the lower end of which is cut off at an angle4 ,it is attached to the gas supply pipe4 ,the tube ,c is connected to the burners4 ,to ,d is attached1 by means of rubber tubing1 a glass bulb ,f1 which is placed inside the drying-box4 ,g ,g is mercury1 and ,h a rubber stopper by which the pressure on the mercury and quantity of air in ,f may be regulated4 ,the action of the instrument is obvious4 ,the gas passes down ,b1 over the surface of the mercury and by the tube ,c to the burner4 ,on the bulb ,f reaching a certain temperature1 the mercury will allow just sufficient gas to pass from the tube ,b to maintain the box at a given heat4 ,if it should fall1 the mercury recedes from the aperture of the tube ,b1 a larger quantity of gas passes to the burner1 and the temperature is restored to a normal degree4 ,if the air in the ball ,f expands to too great an extent1 the mercury rises1 and would eventually entirely close the aperture and cut off the gas supply1 unless the tube ,b is provided with a small hole acting as a by-pass4 ,the tube ,b may be moved up and down through the rubber stopper at ,a as a means of adjustment4 ,illustration3 ,fig4 #c4 ,m4 ,thiel1 of ,paris1 uses a very convenient drying-box1 which1 with his permission1 is here explained4 ,in a brick-lined receptacle under the laboratory floor lies the water-heating apparatus1 which is constructed of sheet copper1 and is capable of containing about four litres of water1 utilised in the production of steam for heating the box4 a1 fig4 #c1 is the pipe passing through the wall into the drying-box2 b is the gas supply pipe to the two atmospheric burners4 ,fig4 #d represents a plan of the drying-box2 c c c c the perpendicular sides of the same1 a a a gives a plan and position and arrangement of the earthenware heating pipes lying in a serpentine form at the bottom of the box1 entirely covered with dry sand1 and this again covered1 as before described1 with tissue paper4 b is the outlet of the steam pipe4 d d d d are movable horizontal iron bars with adjusting screws1 on which the plates are levelled4 ,the box is covered by a hinged lid1 which is raised about a couple of inches during the drying to allow the air to circulate4 ,the dimensions of the box will be determined by the size of the plates to be used1 several of which may be placed side by side4 ,its height is about half a metre inside1 and the plates are placed about its centre4 ,illustration3 ,fig4 #d4 ,glass ,plates1 to be used for printing from1 must as a first consideration have their surfaces ground quite true and parallel4 ,since the introduction of special collotype presses requiring less pressure1 the thickness is of less consequence than formerly1 but for convenience of handling and to withstand the necessary pressure1 in the printing frames1 plates of at least four millimetres in thickness are desirable4 ,many use them from #h to #aj millimetres in thickness2 this1 in the larger sizes1 means a weight both inconvenient and difficult to handle4 ,it is probably easier to work upon plain glass surfaces1 and since means have been discovered of causing the chromated gelatine to adhere to polished glass with sufficient tenacity to produce several hundred impressions1 the employment of ground glass plates is much more a matter of choice than formerly4 ,the ground surface1 however1 assists the formation of a grain in the case of thin layers1 and the operation of grinding serves to remove accidental scratches from the surface of the plates4 ,as in practice these damages constantly arise1 it will in the long run be found both desirable and economical to employ the ground plates4 ,ink ,rollers are also of great consequence in both collotype and lithographic operations4 ,for printing from stone leather rollers have always been exclusively employed1 and they are still used in some collotype establishments1 more particularly where hand presses are yet worked4 ,the ,leather ,roller consists of a wooden cylinder or stock of about #ba to #db cm4 in length and #i to #aa cm4 in diameter1 with handles at either end1 usually turned in one piece with the cylinder4 ,boxwood handles are sometimes let into the ends of the cylinder1 but although smoother to work1 they not infrequently work loose4 ,in using these rollers the handles do not come in direct contact with the hands1 but are covered with a protection of stout leather1 which not only protects the printer's hands from heating1 but enables him by a heavier or lighter grip of the handles to apply a heavier or lighter pressure of the roller--a point of great value in inking the plate4 ,the wooden stock of the roller is first covered with a double thickness of woollen material--flannel or ,melton cloth--and over this is drawn the cover of calf-skin1 flesh side outwards4 ,the manipulation of the seam must be managed with extreme care1 as any unevenness would render the roller useless4 ,at both ends of the cylinder the leather projects1 and is usually drawn tight with string or nailed on4 ,there are two descriptions of leather rollers--smooth and coarse4 ,the latter are only used to apply ink to the stone or plate1 and then1 with the smooth roller1 the proper distribution of the ink is effected4 ,for the latter purpose1 in collotype1 hard glue or indiarubber rollers are employed1 being considered far preferable4 ,when a leather roller is in good order1 and its use has been thoroughly mastered1 it is looked upon by many printers as indispensable4 ,a serious disadvantage is that when new they are almost unusable for collotype1 and after prolonged use the leather stretches1 they become wrinkled1 and this1 of course1 affects the even distribution of the ink4 ,a new leather roller needs a special preparation or 8breaking in0 before it may be considered fit for use4 ,it should be well saturated with a fatty matter1 a very effectual way of doing which is to roll it well at intervals in a moderate supply of thin varnish as used for thinning printing ink1 this process being persevered with so long as the roller continues capable of absorption4 ,a better but more troublesome method is to roll the rollers twice daily in thin varnish1 continuing the operation for a week1 at the end of which time the roller may be well rolled upon the inking slab in stiff black printing ink1 the superfluous ink being occasionally removed from both the roller and slab by scraping with a blunt knife1 and a fresh supply of ink applied4 ,this troublesome and tedious operation should be continued for a period extending over several weeks until it has become quite smooth and even1 though it will still be found better to use it only for common work1 or1 if possible1 on stone4 ,to keep the roller in good condition it should1 on each occasion after use1 be carefully scraped with a clean1 smooth-edged knife--not too sharp4 ,some practice in this operation is required to avoid cutting the leather4 ,great care should be taken to avoid this1 the blade of the knife being held almost flat upon the roller during the process4 ,the scraping should always be in one direction1 to ensure which it is advisable to place a mark upon one of the handles4 ,unless these precautions be observed the ink will dry in1 and completely spoil the leather4 ,if not to be used again for some time tallow should be carefully and thoroughly rubbed into the surface of the roller as a preservative1 but before again using this coating must be removed either by means of a knife or washing with turpentine4 ,glue ,rollers have long been in use1 but chiefly for letterpress work and steam machines in general4 ,a soft composition of a very elastic nature is quite useless for collotype2 its substance must1 on the contrary1 be tolerably hard1 and of a brown colour1 as usually employed on the steam letterpress jobbing machines4 ,for hand rollers for collotype it is preferable to have a strong iron frame with double handles1 as used by letterpress printers4 ,such rollers are preferable to those of leather1 and will answer perfectly for laying on the first stiff ink1 and also for rolling up the half-tones4 ,to clean they should on no account be scraped1 but simply washed with turpentine1 and on this account are much easier cleaned than leather rollers4 ,schaarwchter gives the following as an excellent composition for collotype rollers3 ,brown glue1 three parts1 steeped for two days in cold water4 ,the pieces should then be dried in a cloth1 and afterwards dissolved4 ,when melted add1 with constant stirring1 one part of treacle1 which has been previously boiled1 allow the whole to boil1 and skim4 ,the composition is then run into a thin copper cylinder or mould1 which must be polished smooth1 clean1 and well oiled2 and in the centre of which has been placed the wooden cylinder or stock4 ,after cooling1 the roller is pushed out of the mould1 and washed with alcohol or turpentine to remove any trace of greasiness due to oiling the mould1 placed in a bath of tannic acid1 washed with water1 and dried4 ,the composition rollers1 as used in typographic printing1 are made with glycerine instead of treacle1 and may be used for collotype if not too soft4 ,indiarubber ,rollers are more expensive1 but possess special properties rendering them particularly suitable for photo-lithography4 ,in construction a wooden stock with suitable handles is covered with very thick well-vulcanised indiarubber1 which has a fine smooth surface1 rendering it easy to clean by means of turpentine4 ,if it becomes 8tacky0 on the surface it should be well rubbed with ,french chalk1 or soap-stone1 which will readily absorb the turpentine1 but this coating must be thoroughly removed before again using the roller4 ,an excellent suggestion appeared in one of the polytechnical periodicals1 that the rollers should before use be coated with a solution of pure or bottle rubber in benzole or bisulphide of carbon after having been well washed with turpentine4 ,these indiarubber rollers are not suited for the first inking of the plate1 but are invaluable for rolling up the half-tints of the collotype plate4 ,as they somewhat readily take colour off the plate they must be first rolled up in a thinner ink and a separate slab4 ,according to 8,lithographia0 these indiarubber rollers may be cleaned with lye1 or strong alcoholic spirit4 ,if cleaned with turpentine it may be advantageously followed by rinsing with soap and water2 by so doing the application of ,french chalk is unnecessary4 ,these rollers are1 by comparison with others1 nearly indestructible1 and therefore cheap1 notwithstanding their high first cost4 ,illustration3 ,fig4 #e4 ,velvet ,rollers have latterly come much into use1 and are very successfully used for inking-up the transfers in photo-lithography4 ,they may be also used in photo-xylography and photo-ceramic processes1 and also for certain purposes in collotype4 ,a necessary precaution is that the seam of the velvet should always be kept off the surface subjected to the rolling1 and this may be carried out if the roller is1 say1 #aj-a_/b centimetres in diameter1 a length of #cab centimetres may then be rolled without using the seam4 ,the sketch will explain the construction4 ,the cylinder or stock is of pear-wood1 and the handles of box2 first covering serge1 which before sewing on should be well shrunk in hot water2 over this comes the velvet1 the edges of which must not overlap1 but must be drawn together as close as possible by means of thread4 ,one advantage of this roller is that it is ready for immediate use2 it must1 after use1 be carefully cleaned before being placed aside2 this is best done by repeated rollings on a clean slab1 and the judicious application of a little turpentine4 ,turpentine only may be used to thin ink for use with this roller4 ,drying ,rollers4--,in addition to those already enumerated1 all of which are intended for the application of the ink to the plate1 other rollers are required1 similar in construction1 but covered with wash-leather or cloth1 and used for the purpose of absorbing superfluous moisture4 ,for these it is necessary1 or at least advisable1 that the frames be so constructed that the rollers may be readily removed when by continued use they have become too damp4 ,this method of drying the plates is far preferable to the customary one of wiping with a cloth1 for even with the greatest care1 if the printing should extend over hundreds of copies1 the layer upon the plate will inevitably get scratched when wiping or rubbing is resorted to1 especially if isinglass--which tends to soften the film--be present4 ,palette ,knife or ,spatula4--,it is unnecessary to describe2 they are used for mixing the ink and applying it to the slab and rollers1 and for cleaning the latter4 ,they may be either of hard wood or metal4 ,the ,ink ,slab may be either of slate1 a lithographic stone1 or a sheet of strong zinc securely attached to a block of wood truly planed4 ,the ,press is an indispensable requisite for printing operations4 ,there are small wooden hand-presses1 especially constructed for collotype1 which may be purchased at a very low price--#d to #e2 but the more economical way is to procure a small lithographic press constructed of iron4 ,this will not only be found more durable1 but it may1 if occasion arise1 be used either for lithographic or zincographic printing1 as it will bear the necessary pressure1 which is greatly in excess of that applied in collotype printing4 ,the hand-press constructed by ,sutter is a form that may be strongly recommended4 ,if the output of prints is to be large1 a steam machine will be necessary1 the cost of which will be not less than #bjj to #bej4 ,fig4 #f represents a press which has been largely used for collotype4 ,d is the bed or carriage upon which the plate is fixed in the manner described further on4 ,by turning the crank handle ,c the bed is carried under the scraper1 which is secured in the scraper-box ,a4 ,the scraper is kept in position by the lever ,b4 ,the scraper-box is represented as closed down in the illustration1 but in actual practice it would not be in the position shown until the tympan-frame ,e had been lowered4 ,the ,tympan1 of either leather or thin sheet zinc or brass1 is marked ,f in the illustration4 ,all iron portions of the press subject to friction should be frequently cleaned and carefully oiled with a good machine-oil4 ,illustration3 ,fig4 #f4 ,the ,scrapers should be of either pear tree1 lime1 maple1 or preferably box1 with a blunt bottom edge1 which should be planed true1 and finally finished by rubbing on a sheet of glass-paper placed upon a perfectly flat surface4 ,they must be adjusted with even more precision than is necessary in lithography1 as owing to the difference in the printing surface1 the same pressure cannot with safety be applied4 ,with plates or stones of large size it will be found that the pressure of the scraper will be unequal1 greater pressure being exerted in the centre than upon the edges of the printing surface4 ,many printers1 to counteract this tendency1 slightly scrape away or hollow out by means of a piece of glass the centre of the scraper4 ,with sufficient pressure and plenty of elastic packing between the printing paper and the tympan1 this slight difference may be easily overcome4 ,several scrapers should be provided of various lengths1 so that one of suitable size may be always available to suit the particular work in hand4 ,it should always be slightly longer than the width of the picture1 but shorter than the width of the stone or plate4 ,by pressing the edge of the scraper to the surface of the latter and looking towards a window no light should be visible between the two surfaces4 ,if the edges of the scraper are carefully rounded1 it may be covered with a strip of wash-leather1,g smooth side outwards1 and secured by means of tacks1 by which arrangement the pull will be easier1 the impression more even1 and the tympan and scraper will last longer4 ,the accompanying sketch represents one of ,poirier's special collotype presses1 constructed entirely of iron4 ,the details are so clearly shown in the engraving that after the description already given it will be unnecessary to point out further details4 ,g ,this is necessary only with metal tympans4 ,white ,margins to ,pictures4--,to facilitate the production of pictures with white margins1 instead of using a mask of paper either oiled or treated with a varnish1 an arrangement has been introduced1 as represented in fig4 #g1 the design of which is due to ,mr4 ,raph4 ,schlegel4 ,the drawing is not perspectively correct1 but is made to show as clearly as possible the arrangement and manner of working4 ,the scraper--not shown in the illustration--works on the tympan ,o4 ,a1 carriage or bed of the press1 carrying the printing plate4 ,b1 a slide of light wood4 ,this prevents the frame ,d and the printing paper ,m coming in contact with the plate before the impression is actually being taken by the scraper4 ,the wooden slide bridges over the plate1 and may be #ae to #be millimetres higher than the plate itself4 ,when the rolling up or inking of the plate has taken place the slide is pushed so far forwards as to allow only just sufficient room for the scraper to rest upon the plate4 ,the action of the scraper during the taking of the impression causes the slide to work out1 and allows the paper to come in contact with the print layer4 ,e ,e are adjustable buttons to regulate the traverse of the carriage when printing4 ,d is a second frame necessary to carry the strips of thin zinc1 ,ef ,ef1 ,eg ,eg1 which entirely protect the edges of the paper to be printed upon1 and so produce an impression with a white margin4 ,these strips may be almost instantly adjusted to give any required size4 ,the frame ,d must be so much smaller than the frame ,l as to be easily covered by the latter1 allowing for the projecting screws and nuts of the clamps f4 ,the zinc strips should be reduced to a feather edge on the sides next the picture1 and should have secured to them strips of fine paper 7foreign letter-paper71 which should extend over the edges about three millimetres1 to prevent damage to the gelatine layer4 f f are clamps for the zinc strips ,ef4 ,they are put through the slots1 and the tension adjusted by the nuts4 ,the zinc strips are perforated by two holes at each end1 and secured to the clamps by means of screws4 ,eg are also zinc strips2 g clamps provided with two holes1 in each of which a hook is inserted4 ,corresponding with these a second pair of hooks are inserted in holes in the frame ,i1 the hooks being connected together by the strong indiarubber bands h4 ,this gives to the strips ,eg a certain amount of elastic tension4 ,the clamps ,k are also adjustable in slots1 and similar to f2 ,l1 frame for the reception of the tympan2 ,m1 large clamp for stretching the elastic sheet ,o2 ,n1 zinc tympan1 greased to facilitate its movement under the scraper1 it also prevents grease penetrating the sheet ,o2 ,p1 a bracket on bed ,a1 against which the tympan frame rests when raised and thrown back4 ,the arrangement is used as follows3 ,when the plate has been satisfactorily inked or rolled in1 the slide or bridge ,b is adjusted over the plate1 leaving a strip of about three mm4 uncovered to allow of adjustment of the scraper4 ,lower the frame ,d in which the zinc strips have been adjusted to the size of picture2 the printing paper is placed over this slide1 and covered with a few sheets of paper backing4 ,the tympan frame ,l1 together with the sheeting and greased zinc plate1 are lowered upon the work1 the scraper adjusted1 and an impression taken4 ,illustration3 ,fig4 #g4 ,,chapter ,v4 ,,chemicals ,,and ,,materials ,,for ,,collotype4 ,gelatine4--,the basis of the ,collotype process is gelatine--the finest purified animal glue--and the important part it plays in the process demands an acquaintance with its properties1 which are found to differ widely1 according to its origin and method of preparation4 ,gelatine suitable for ,collotype should be free from all impurities--particularly alum1 which is not infrequently added in small quantities during manufacture4 ,dr4 ,eder1 in particular1 has made most minute examinations of various samples1 more especially with regard to their suitability for ,collotype1 ,carbon1 and the ,galvanographic processes1 and his opinion1 agreeing with that of other experimentalists1 is here quoted3-- ,the two principal modifications of gelatine are those produced from bones1 sinews and skins of animals1 and from the air bladder of the sturgeon1 the latter variety1 better known under the name of isinglass1 represents1 from a chemical point of view1 glue in the purest form4 ,on account of its high price and ever-varying quality as found in commerce1 it must in practice give place to a glue or size containing chondrin1 and prepared from bone and gristle4 ,another objection is1 that plates prepared with an admixture of isinglass are less durable than those containing gelatine only4 ,on the other hand1 it certainly possesses advantages of its own1 which will be more fully considered hereafter4 ,a gelatine suitable for collotype must absorb plenty of water and swell out1 but not liquefy after having been soaked in cold water for twenty-four hours4 ,gelatine or isinglass prepared from the bladder will not stand this test1 but1 on the contrary1 partially disintegrate4 ,the consistency and bearing capacity of a jelly formed by dissolving gelatine in water by means of heat and allowing it to cool1 form1 in the opinion of ,lipowitz1 a safe and reliable means of forming a judgment as to its suitability for collotype4 ,dissolve by first soaking five grammes in #de cm4 of distilled water for several hours1 afterwards apply heat1 and allow to stand twelve hours to set4 ,for purposes of comparison this should always be done in a glass of the same diameter4 ,a small tin or zinc slip is placed across the top of the glass vessel containing the jelly2 through the centre of the tin a hole is pierced1 through which a wire moves easily up and down4 ,to its bottom end is soldered a piece of tin1 of about #ae cm4 diameter1 the convex side lying upon the surface of the gelatine4 ,on the other or upper end a small funnel is placed1 large enough to contain #a-a_/b kilo4 of small shot4 ,the weight of the wire and funnel being ascertained1 it will be a simple matter1 by also weighing the shot1 to calculate the weight required to sink the instrument into the jelly1 and to ascertain with accuracy its weight-bearing capacity and proof of the relative value of various samples for ,collotype printing4 ,if otherwise suitable1 the variety capable of supporting the greatest weight before yielding will be the one to select4 ,the power of absorption of different samples varies considerably2 for example1 the ,collotype gelatine of ,creutz absorbs in two hours #cj parts of cold water poured over it4 ,nelson's patent opaque1 in the meantime1 only absorbs five parts1 but after a further period of #d-a_/b hours the difference is equalised1 as it will absorb #be parts more of water1 making altogether exactly #cj parts4 ,this experiment proves the latter to be a harder quality than that of ,creutz1 and it necessarily requires a somewhat different treatment for the production of the best results4 ,isinglass or fish glue1 although1 as before stated1 a finer quality of glutin than the ordinary gelatine of commerce1 is1 on account of its high price and varying quality1 comparatively little used4 ,the addition of this substance also softens the gelatine layer4 ,on the other hand1 it possesses certain properties which render its use at times desirable2 for instance1 it does not dry so completely as gelatine1 the layer prepared with it consequently gives cleaner and more even proofs1 a point particularly noticeable in the earlier impressions4 ,such prints will also exhibit greater brilliancy1 and this is of especial consequence in work produced from photographs from nature1 in which class of work the half-tones are too often wanting4 ,some operators take even equal parts of isinglass and gelatine1 but such layers must be very thin1 and dried quickly4 ,thick layers are liable to crack or fly1 and in use to refuse to take the ink1 which must for such film be used in greater quantity and thinner than when gelatine alone is employed4 ,a solution of isinglass is not so readily prepared as one of gelatine4 ,it is necessary to allow it to soak in cold water for from twelve to twenty hours1 and the temperature then gradually raised to nearly boiling point1 at which heat it should be maintained for some time longer1 and then filtered through flannel into the gelatine solution4 ,in printing from these plates1 particularly when the proportion of isinglass exceeds one-third the amount of gelatine1 there is a disagreeable tendency of the printing paper to adhere in the high lights--that is1 in those parts of the print layer which are represented in the negative by entire opacity--as in the sky of a landscape or a background which has been 8stopped out0 on the negative4 ,on other portions of the plate where the light has more fully acted--during the printing in the printing frame--this troublesome defect will not be observed4 ,the fault is more noticeable when the dull enamel paper is used1 while a hard1 well-sized letter paper presents the other extreme4 ,further details of printing papers will be found in another chapter4 ,in the introductory chapter of this work the photo-chemical qualifications of the bichromates of ammonium and potassium with regard to collotype are considered4 ,bichromate of ,potassium is found in the well-known rich orange-red crystals4 ,it is readily soluble in cold water 7#a4aj74 ,it may be easily recrystallised and purified readily out of either a hot1 warm1 or cold solution1 and forms in thin layers of fine crystals4 ,therefore1 in using it for collotype1 care is needed not to exceed the strictly necessary proportion1 as the plate may be hopelessly spoiled by the partial crystallisation of the salt1 which will probably show during the process of drying4 ,the maximum addition of bichromate of potassium in proportion to the weight of the gelatine may differ according to the peculiarities of the latter4 ,dr4 ,eder considers about #c_/aj to #d_/aj by weight of this salt in a dry state may be added to a gelatine1 which will absorb from six to ten times its weight of water1 without fear of crystallisation4 ,there are1 however1 many gelatines that are incapable of working with more than #b_/aj4 ,rapid drying of the plate in a current of air1 and at a temperature of #dj ,c41 will1 to some extent1 obviate this objectionable feature4 ,by reason of its comparative insensitiveness to light and this facility of crystallisation1 and notwithstanding its comparative low price1 it is now far less used in collotype than ,bichromate of ammonium1 the crystals of which somewhat resemble those of the potassium salt4 ,in colour they are of a browner hue1 and readily distinguishable1 since when heated on platinum deflagrates1 emitting sparks and leaving a residuum of very finely-divided oxide of chromium4 ,the ammonium salt does not1 however1 so readily crystallise on account of its considerably greater solubility in water compared with bichromate of potassium4 ,by comparison1 #ab parts of the ammonium salt are equal to #ae parts of that of potassium4 ,at least #a_/c to #a_/d more of the former may be used without disadvantage or fear of it crystallising out2 it will1 on the contrary1 improve the quality of the film or layer4 ,the ammonium salt will also be found comparatively more soluble in hot water1 but care must be exercised that the solution never reaches the boiling point1 neither should the heat of the drying box ever exceed #ej to #fj ,c41 or the films will present a pale brown appearance1 and will prove alike insensitive and partially insoluble4 ,the single and tri-salts1 offering no advantages over those already described1 may be dismissed without further consideration4 ,it may be remarked for non-chemists that the addition of any acid to the chromated gelatine solutions inclines to the formation of trichromates of the alkalis2 and1 on the contrary1 the addition of free ammonia1 or any other free alkali1 produces simple chromates4 ,the addition of ammonia to the chromated solution has been strongly advocated in many quarters1 but as the result of numerous experiments1 it may be definitely stated that the supposed advantages are more than counter-balanced by the numerous disadvantages arising from such addition4 ,the mixing1 in equal or other proportions1 of the potassium and ammonium salts has been recommended1 but there is no real gain or sufficient reason for preferring any of these combinations to the ammonium salt alone4 ,besides the chromates of the alkalis1 several other salts as well as acids are used in ,collotype printing1 although seldom1 and then only in small quantities and for special purposes1 such1 for instance1 as hardening the print layer1 or for the purpose of facilitating the retention of moisture in the film4 ,for the former purpose small quantities of chrome alum are sometimes added2 while for the latter chloride of sodium or chloride of calcium are sometimes added to the chromated gelatine solution at the time of coating the plates1 or are added as ingredients to the so-called etching or damping solution which is frequently applied to the plates during the printing4 ,glycerine answers for this purpose1 and is to be preferred4 ,it should be borne in mind that all additions to the film to facilitate its retention of moisture lessen its adhesiveness to its support4 ,and with regard to the direct addition of the substances mentioned to the film during the preparation of the plates1 it is not very apparent how such readily-soluble matters can remain in the film after the prolonged and careful washing the plates should be subjected to after exposure in the printing frame4 ,on these grounds the addition of such substances to the damping solution is more rational and certainly more effective4 ,alum and ,chrome-,alum causes the gelatine to set sooner without precipitation1 and harden the layer considerably after drying1 and although gelatine1 as well as glue1 always contains more or less chondrin1 which is precipitated by alum1 great care is necessary in the addition of the latter2 and it is better that such addition should be made immediately before the hot solution be poured upon the plates1 otherwise a precipitation will ensue1 which1 although very finely divided and at first scarcely visible1 will become more apparent during the drying of the plates1 and finally show in the picture in innumerable white spots4 ,silicate of ,soda is almost indispensable as a substratum in the preparation of collotype plates1 although many practical workers still adhere to the method originally proposed and practised by ,j4 ,albert1 of ,munich1 who used as a substratum a chromated solution of gelatine and albumen1 rendered either partially or wholly insoluble by exposure to light4 ,the silicate is here considered as having about the consistency of syrup4 ,if more fluid the adhesive power of the substratum will not realise expectations1 and the plates will require very careful handling if even a few hundred impressions are required4 ,the composition of the film1 the exposure of the plate through the back1 and the careful treatment of the layer in the actual printing operations are all matters which considerably affect the 8life0 of the plate1 and to which we shall again return4 ,chloride of ,zinc is used for hardening special parts of the collotype plate1 and is easily prepared by dissolving--to saturation--sheet zinc in hydrochloric acid1 filtering1 and reducing as circumstances may demand4 ,tannin and ,tannic ,acid in strong solution harden the film1 and may be applied to certain parts to cause it to 8take0 the ink4 ,for instance1 to remove1 or rather harden1 spots which refuse the ink and consequently show upon a dark ground2 and also to write names or titles to the plates4 ,written additions of this character must1 of course1 be reversed1 as in lithography4 ,the addition of tannin to the chromated gelatine before coating the plate is recommended by ,waterhouse1 he considering such addition confers greater lasting power to the films so treated4 ,cyanide of ,potassium and ,ammonia4--,all alkalis or carbonates of the alkalis have a directly opposite effect upon the printed layer to that last referred to4 ,by the judicious use of one or the other of these agents spots printing light or dark may be either removed or considerably modified4 ,glycerine and ,sugar and similar easily soluble organic substances1 added to the chromated gelatine1 would assist the easier and evener damping of the plate1 but render it more susceptible to damage1 and the desired effect is better attained by suitable additions to the damping water4 ,organic ,acids4--,citric acid and tartaric acid are recommended as additions to the chromated gelatine1 partially as influencing the so-called 8grain10 and also as additions to the damping solution to facilitate the production of cleaner prints4 ,experience with these substances shows that the print layer suffers from their use1 and for clearing up a plate inclined to yield dirty impressions a weak solution of ammonia is far preferable4 ,nitric ,acid has even been recommended for occasionally damping the plate in certain cases1 after which the most delicate half-tones should be reproducible4 ,an experienced collotypist ought never to be under the necessity of adopting such desperate remedies1 which more often than not rapidly and entirely spoil the plate1 and it is better to at once prepare a new one4 ,ox ,gall remains to be mentioned as exercising a beneficial influence upon the print layer under certain circumstances4 ,it considerably hardens the gelatine1 and tends to reduce the annoying tendency of the film to adhere to the paper in the high lights4 ,ox gall was first used at the ,royal ,printing ,works in the 8glass0 printing process there utilised for the reproduction of line subjects4 ,some operators of eminence consider that in collotype its use should be strictly confined to lineal representations1 as by its continued use the half-tones are partially lost4 ,,ink ,,and ,,paper4 ,of great importance is the careful selection of the materials for the printing proper--i4e41 the printing inks and papers1 and the sometimes necessary admixtures of the former4 ,printing ,ink4--,the most simple and suitable of all greasy or oily printing ink is the best chalk ink1 as used in lithography4 ,it is composed of finest lamp black thoroughly incorporated with boiled linseed oil 7varnish74 ,the collotypist must1 in addition to different coloured ink for mixing with the black1 be provided with thin boiled oil 7middle varnish71 and also turpentine and olive oil1 the latter being used to thin or reduce the printing inks1 which1 as usually supplied to the trade1 are too stiff for immediate use4 ,when in printing it is necessary or intended to use an admixture of several colours1 they must be first well ground in turpentine and the latter allowed to evaporate4 ,a small addition to the chalk ink of indigo or ,prussian blue greatly improves its colour and printing power1 but may be considered more suitable for the reproduction of line or stipple subjects4 ,a dash of ,venetian red or carmine imparts to the chalk ink a warmer tone1 resembling the colour of an ordinary silver print4 ,whoever ventures on colour printing must be able to prepare all the necessary combinations with the greatest exactness1 and should use for each a special inking slab and roller4 ,in the chapter dealing with the printing1 further particulars will be given as to the mixing and thinning of the colours4 ,the ,quality of ,paper suitable for collotype may be next considered4 ,without doubt the best is that known as dull enamel1 or chalk paper1 which is now supplied of a pink tone as well as of the ordinary white quality4 ,it should not be glossy or adhere too strongly to the printing surface1 as the enamel will1 under such circumstances1 be partially or wholly torn from the paper1 a difficulty equally observable whether the paper be used damp or dry4 ,as previously observed1 the adhesive power of the printing surface increases with the softness of the same4 ,this may arise from using a small percentage of bichromate or a short exposure to light1 in which cases it is always more apparent in such parts1 as the densest portion of the negative may have been entirely protected during the copying in the printing frame1 or it may arise from the addition of too great a proportion of isinglass4 ,on the other hand1 a gelatine film strongly chromated1 proportionately longer exposed1 and in which there is no isinglass1 will be less likely to exhibit this annoying tendency4 ,well-sized fine glazed papers generally adhere least1 and are usually laid on dry4 ,when the impressions are to be issued without glaze very thin fine-surfaced cardboard--not enamelled--is frequently used1 and the margin of the printing plate covered with a suitable mask4 ,any well-sized paper possessing a fine surface may be used4 ,impressions on such paper may be passed through a weak solution of gelatine1 and after drying1 rolled1 varnished1 mounted and again rolled4 ,any retouching must be done immediately after the sizing1 and before the application of the varnish4 ,enamelled papers require a special glaze1 not a lacquer1 or are finished without glaze at all4 ,,chapter ,,vi4 ,,preparation ,,of ,,the ,,collotype ,,plate4 ,the well-polished glass plate must be thoroughly cleaned with alcohol and ammonia1 and it should be ascertained that the surface is entirely free from scratches4 ,it is then coated with the substratum1 consisting of a dilute solution of silicate of soda and albumen4 ,the following formula is in constant use by many practical workers of experience1 and answers every requirement3-- ,distilled water #h parts4 ,white of egg--whisked #g 0 ,silicate of soda 7of the consistency of syrup7 #c 0 ,this mixture should be well beaten to a froth or put in a bottle with pieces of broken glass1 well shaken1 and placed aside to settle for half-a-day4 ,then filter through paper1 which should be replaced so soon as the pores become choked4 ,to facilitate the operation the filter paper should before use be moistened with distilled water4 ,the surface of the plate should be flooded with water1 and coated as evenly as possible with the above solution1 a small glass rod being made use of to assist the flow4 ,air bubbles must be removed1 and by quickly tilting the plate the superfluous solution run off2 this should not be used to coat other plates without being again carefully filtered4 ,if the substratum be thin1 it is not necessary to wash the plate after drying1 but after standing aside two days to harden1 with dusting and warming1 they may be coated with the chromated solution of gelatine4 ,if small crystal formations appear on the surface the plate should be well washed and again dried before proceeding further4 ,the following formula for substratum is due to ,m4 ,thiel1 senior2 it contains less silicate1 and the washing before applying the sensitive coating is never necessary3-- ,distilled water #cf parts4 ,white of egg #bj 0 ,silicate of soda #fb 0 ,stale ,beer4--,albumen is sometimes replaced by beer1 from which by frequent outpourings the carbonic acid has been removed1 and to which caustic potash has been added until it fails to show an acid reaction when tested with blue litmus paper 7about three to five grammes of caustic potash to the litre of beer will be necessary74 ,to a litre of beer so prepared is added #a_/c kilo4 of silicate of soda4 ,the main points in this and also the following operations are careful filtration1 even coating and drying in a clean place entirely free from dust4 ,plates previously used or somewhat scratched must before further use be thoroughly cleaned and the face reground with the finest emery powder4 ,the ,sensitising ,solution4--,this is manifestly the most important matter in the ,collotype process1 for on it depends not only the durability of the printing plate1 but also the method of procedure in the subsequent operations4 ,it may be here intimated that plates prepared by the very best formula cannot be expected to yield good impressions if the whole of the manipulations are not carried out with the greatest care1 and it should be noted #a4 ,that neither too much nor too little of the chromated gelatine should be allowed to remain upon the plate4 ,it is impossible to lay down a hard and fast rule1 and the exact amount must be determined by the experience of the operator4 ,of equal importance1 and naturally connected with this operation1 is #b4 ,the even distribution of the solution1 the flow of which may be assisted or directed by the aid of a small glass rod1 and by allowing it to run off more or less at each of the four corners of the plate4 ,considerable experience has demonstrated that the coating is applied most easily and in the evenest manner by resting the plate--previously warmed to about #de ,c4--as horizontally as possible on the cork of a heavy bottle1 the latter standing in the centre of an earthenware dish4 ,a sufficient quantity of the solution1 carefully filtered1 and heated to #de to #ej ,c41 is then poured on to the centre of the plate and rapidly spread over it with a glass rod1 previously well warmed4 ,so soon as the surface of the plate has been entirely covered a further supply of the hot gelatine solution is quickly poured on and partially run off at each corner4 ,a scarcely perceptible inclination should be given to the plate1 otherwise the layer will be too thin2 it ought to be about the thickness of four or five sheets of ,rive paper of #h kilo4 per ream4 ,it should be borne in mind that the addition of isinglass will necessitate a comparatively thinner layer than when gelatine is used alone4 ,to obviate the gelatine coating becoming uneven great care must be exercised in removing the plates--when coated--to the drying-box1 the levelling screws of which have been adjusted with great accuracy4 ,the box should be heated to a temperature not exceeding #ej ,c4 ,to satisfy the adherents of isinglass1 two eminently satisfactory formul are here given-- ,,with ,,gelatine ,,only4 ,collotype gelatine #f grams4 ,water #gjj ccm4 ,the gelatine is first soaked in the water for one hour1 and then complete solution effected at a moderate temperature1 and the solution filtered through best filter paper4 ,boiling heat is never required4 ,japanese filter paper is the very best4 ,heat will be necessary during the operation1 which may be conducted either in the drying box or a warm oven4 ,when filtered1 add1 with constant stirring1 #h ccm4 of a solution of bichromate of ammonium in water 7#a in #h1 so that #h ccm4 solution contains #a gramme of the ammonium salt71 which should also be thoroughly filtered before addition to the gelatine4 ,the combined solutions being well incorporated1 clear and free from air bubbles1 should1 as previously described1 be heated to #dj or #ej ,c41 poured upon the warmed plate1 and at once conveyed to the drying box1 the temperature of which has been slightly raised4 ,the box should be closed1 and gradually increased to #ej ,c41 at which heat it should be steadily maintained until the drying is complete1 which usually occupies one to one and a-half hours1 varying somewhat according to the thickness of the coating and the strength of air current1 which is necessary to the proper and rapid drying of the films4 ,it may1 under some circumstances1 be necessary to augment the admission of air2 this may be done by slightly raising the lid of the drying box4 ,the current must freely circulate in all parts of the box1 and remain as constant as possible4 ,if subjected to sudden fluctuations in the air current or temperature1 the plates will dry unevenly1 and endless troubles ensue4 ,the ,grain4--,the so-called grain which is necessary for the printing first shows itself on the completion of the washing of the plates after printing in the copying frame4 ,it is a peculiar1 net-like formation1 varying in fineness1 and similar in character to the unwelcome appearance known to carbon printers as reticulation4 ,it arises in consequence of the uneven distribution of the soluble layer in comparison to the substratum4 ,in ,collotype1 its production is promoted by thicker layers and slower drying at a temperature of #de to #ej ,c4 ,the addition of isinglass also seems to aid the production of grain4 ,certain varieties of gelatine which possess great power of absorption give a smaller grain4 ,creutz's gelatine may be mentioned as an example of this class4 ,an addition in small quantities of dilute acid1 particularly those of organic origin1 as acetic or tartaric1 tend likewise to the production of grain4 ,insoluble powders1 as of glass or flint stone1 may be added1 but only in the very finest state of division1 and in very small quantities4 ,,formula ,,with ,,isinglass4 ,two grammes of the best ,russian isinglass are cut up into the smallest possible pieces with a pair of sharp scissors1 soaked in #be cc4 of water for #ab hours1 heated nearly to boiling point until solution is effected1 and then filtered while hot through close flannel4 ,cover six grammes of good ,collotype gelatine with #ej ccm4 of water and allow to stand1 heat nearly to boiling point and thoroughly incorporate the two solutions1 again1 while hot1 filter through paper or close flannel4 ,to this is added #aa cc4 of the filtered solution 7#ah7 of bichromate of ammonium1 as previously referred to4 ,the complete solution is then heated to #ej ,c41 or should it exceed that temperature it is allowed to cool to it1 and the plates warmed1 coated1 and dried in the manner previously described4 ,it is not advisable to overcrowd the drying-box by attempting to dry too many plates at the same time3 it necessitates a too frequent examination of the contents and so interferes with the evenness of the drying1 and as this is a point of even vital importance no risk should be incurred4 ,the plates being properly dried allow them to remain in the box for some time longer1 the source of heat being either removed or extinguished1 and the whole allowed to cool gradually4 ,if the plates are removed too quickly in their fully-heated condition--particularly when thickly coated--the too rapid contraction of the glass will crack and destroy the film2 by gradual cooling such accidents are avoided4 ,when finished the plates may be kept in a cool1 dry place for two or three days4 ,many operators keep them this length of time purposely1 believing they thereby obtain finer results4 ,the plates so kept must1 of course1 be thoroughly shielded from actinic light4 ,negatives1 with regard to their suitability for ,collotype1 may here be considered1 as the after result naturally depends considerably on their adaptability to the process4 ,they should be quite free from fog or yellow stain1 and for half-tone subjects not too intense4 ,the greatest difficulties will present themselves in the production of portraits or such work from nature by the ,collotype process4 ,photographer and printer ought1 so to speak1 to work hand-in-hand4 ,the negative must show the finest gradation from clear glass in the shadows to the necessary density in the high lights1 quite free from veil or fog1 and intensified very little1 if at all4 ,they should be produced in a studio where the light is thoroughly under control4 ,if not to be stripped all negatives should be taken on patent plate and protected by a coat of varnish1 sufficiently thin to offer no obstacle to the production of sharp prints1 and yet sufficient to obviate in a great measure the risk of damage by the pressure it is subjected to in the pressure frame in contact with the unyielding surface of the ,collotype plate4 ,the risk of breakage at this stage always renders stripped films preferable1 their elasticity better enabling them to withstand the pressure4 ,the gelatine layer applied to the negative before stripping must be as thin and even as possible1 as from thick or uneven films it is almost impossible to produce a sharp print4 ,if the negative is of a line subject1 and it is desirable to have clear whites that the impressions may resemble as much as possible the original1 the lines in the negative must be clear1 but the remaining portions of great density4 ,the ink for such work should consist only of pure chalk printing ink1 which will be generally found to give stronger contrasts than the usual mixed ,collotype inks4 ,retouching ,negatives and ,plates4--,the negatives must have all defects made good by the retoucher1 all blemishes being moderated as far as possible4 ,retouching on the ,collotype plate or print should not be required2 but this is seldom so1 as during the printing the negatives frequently sustain slight damages4 ,retouching the printing surface is seldom very successful4 ,the alteration easiest effected is the removal of small light spots which refuse to take the ink1 and such may be removed by touching with a fine brush dipped in a strong aqueous solution of tannin1 this alteration being made upon the finished plate after it has been washed and dried4 ,with this tannin solution inscriptions may be inserted which have to appear black in the print4 ,or a solution of gum arabic1 to which has been added a solution of bichromate of potassium1 may be used1 and after such addition the plate is once again exposed to light4 ,writing which has received too much exposure1 and which should appear in the finished print black on a white or light ground1 often appears white4 ,this defect arises from the gelatine on which the light has had little or no action swelling to such an extent that the letters are buried or sunk into the plate too deep to be touched by the roller when the plate is inked4 ,it may be rectified by further thinning the ink with varnish4 ,the removal of dark spots from the print layer can never be completely effected4 ,ammonia1 cyanide of potassium1 oxalic and other acids have from time to time been recommended1 but this treatment will prove effective for only a few impressions4 ,negatives should therefore be very carefully and systematically retouched and carefully preserved from damage during the printing4 ,another method of applying writing1 such as the names of firms1 c41 is to get them printed from small type on thin gelatine films and attach them to a clear or erased portion of the negative during the printing in the pressure frame4 ,writing so added will appear as white letters on a black ground4 ,it will often be found practicable to attach the written or printed matter to the original while photographing1 and so include it in the negative at one operation4 ,printing under the ,negative4--,the printing of half-tone plates is best performed in diffused light2 to hit the exact exposure is as important as it is difficult1 and depends not only on the actinic power of the prevailing light1 but also on the quality of the negative and the sensitiveness of the layer4 ,the greater the amount of bichromate the latter contains1 the greater its sensitiveness1 and consequently the exposure is shorter than for one containing less of the sensitising salt4 ,a thinner layer must not be printed so long as a thicker one1 or dark prints1 lacking in contrast1 will result4 ,on the other hand1 a thicker layer may be submitted to a comparatively longer exposure without harm2 the exact time must not be greatly exceeded or it will happen that the blackest portions1 written titles for instance1 will not take the ink4 ,during printing1 one may with advantage shade such portions a little4 ,the examination of the back of the ,collotype plate is the safest method of judging the correct exposure during the copying1 but every precaution must be observed during such examinations that neither the plate nor negative be moved from their original position4 ,only when the negative is very clear may the picture be seen by reflected light as a positive2 it will in such cases appear on a dark ground4 ,it will be found difficult1 particularly for a beginner1 when making an examination in the copying frame1 to distinguish between the dark original picture and the pale brown image of the ,collotype plate1 as they naturally completely cover each other4 ,by the dark brown tone of the uncovered margin of the print layer a certain indication is afforded of the completion of the copying4 ,an ,actinometer may be used as an exposure gauge1 as in carbon printing1 and as a slight indication of the necessary exposure4 ,when using the small cube,h photometer with chloride of silver paper1 five to seven tints may be printed1 but the different modifying circumstances previously referred to must all be duly considered4 ,under a clouded sky in winter1 using a dense negative1 it may take a whole day to complete the copying1 while in clear direct sunlight1 perhaps1 from the same negative1 a quarter of an hour would suffice4 ,h ,the scale actinometer is one requiring less attention4--,,trans4 ,masking should be resorted to to form a margin at least an inch wide round the four sides of the negative1 either by painting round the same with ,indian ink1 or by attaching to the negative strips of opaque paper1 or1 better still1 thin tinfoil4 ,sunning4--,when sufficiently exposed1 i4e41 when the brown picture with all its half-tones and details is complete1 the plate is removed from the copying frame and placed1 face downwards1 upon a piece of black velvet1 and exposed for a short time--five to ten minutes--to a good but not direct sunlight1 so that it may pass through the glass plate and harden the back of the print layer4 ,a sheet of ground glass may be placed over the plate to thoroughly diffuse the light1 and prevent any scratches or damages to the back of the glass plate producing any detrimental effect upon the printing surface4 ,washing the ,plate is the next operation4 ,the plate is removed into the dark room and placed in clean cold water1 which should be often changed--every half-hour--unless an automatic washing apparatus,i is used2 this is continued until the plate no longer has a yellow appearance1 and the picture is visible only as a slight brown image4 ,i ,jefferies's ,patent 8,perfect0 ,washer is a very suitable appliance1 and may be used for ,collotype plates1 negatives1 or paper prints4--,,trans4 ,hardening the ,film is effected by soaking it for a quarter of an hour in a one per cent4 solution of alum4 ,the plate is again washed1 and the surface evenly dried with fine tissue paper1 and placed aside for at least two days that it may thoroughly dry4 ,an ,alcohol ,bath is used by many operators to immerse the plate in for half an hour after drying it with paper1 perhaps with the intention of drying the film quicker1 or to strengthen the layer and assist the formation of the grain1 but there is no gain by this procedure1 and1 as the bath is an expense1 it may be omitted4 ,the ,damping ,solution1 or so-called etching fluid1 is of much greater importance1 and it is necessary that the plate be submitted to it before printing be attempted4 ,tinted ,grounds often enhance the appearance of prints1 and may be imparted to them by the addition of an aqueous solution of red1 yellow1 or other suitable colour1 to the damping solution1 which is applied in the ordinary manner4 ,the plate is superficially dried1 inked up1 and printed from in the usual way4 ,,chapter ,,vii4 ,,negatives ,,suitable ,,for ,,collotype4 ,a ,collotype plate may be readily produced from any negative1 but the highest results are naturally only obtained when the negative is prepared with a view to its special use4 ,first should be considered the question--,may the negative1 without detriment to the finished print1 be utilised without a reversal8 ,in the not very frequent case of this important point being immaterial1 it is simply necessary to produce the negative on patent plate1 and it is at once available for printing from4 ,as the negative may easily sustain damage in any of the various operations1 it should be thinly and evenly varnished2 this1 while affording protection1 does not mar the sharpness of the resulting print to any appreciable extent4 ,reversed ,negatives4--,in the majority of cases1 the resulting copy has to exactly correspond with the original as regards the position left and right1 and in such cases the negatives will have to be reversed4 ,this is usually effected in one of four different ways-- #a4 ,reversal of the image by reflection with a prism or mirror1 or reversing the plate4 #b4 ,stripping the negative from the glass4 #c4 ,by the dusting on or powder process4 #d4 ,by the use of negative films4 ,the second is that usually adopted4 ,with regard to the special features desirable in negatives for ,collotype1 one giving a good silver print will answer equally well for ,collotype--they should incline rather to softness than the other extreme4 ,it has been remarked that they should be as free from veil or fog as possible1 and may be intensified or not according to the judgment of the operator4 ,portraits from ,nature1 with their fine half-tone1 and at the same time necessary contrast of light and shade1 are the most difficult to reproduce in ,collotype4 ,the negatives should be perfect in gradation1 and such as are usually only obtainable from a talented operator who has the lighting of his studio entirely under his control4 ,black and ,white subjects1 on the contrary1 for their satisfactory reproduction1 require a negative of the utmost density1 but perfectly clear in the lines4 ,such are better produced by the collodion process1 as directed for photo-lithography4 ,for subjects in lines or dots entirely free from half-tone1 photo-lithography is more suitable for reproduction than ,collotype1 where price is a consideration4 ,reversal by ,reflection1 by means of a mirror or prism1 necessitates a special and rather expensive apparatus1 and the exposure being somewhat lengthened1 it is1 although quite successful1 more suitable for lifeless objects4 ,stripping the ,collodion ,film is a safe and cheap procedure for producing the necessary reversal1 and in the subsequent printing operations the danger of breakage1 when compared with glass1 is reduced to a minimum4 ,the glass plate1 free from defects1 must be well cleaned1 and it is safer1 and renders the stripping more certain1 if it be covered with a fine film of pure beeswax4 ,this is best applied by rubbing over the surface a few drops of a solution of beeswax in benzole and carefully polishing1 at the same time avoiding the entire removal of the wax4 ,the piece of linen used in the operation should be rubbed upon a lump of wax previous to the polishing4 ,the plate must on no account be gelatinised or albumenised1 except round the edge only1 as a precaution against premature slipping4,j ,use a tough collodion1 and otherwise proceed as usual for the wet process4 ,after the negative is finally washed and dried it should be varnished with a thin solution of gum arabic1 to which has been added a few drops of a solution of chrome alum4 ,after complete drying the margin or edges of the plate are rubbed with a little tallow4 ,to prevent overflow the plate is accurately levelled and flooded with a solution of #aj parts gelatine soaked in #fj parts of water and dissolved by heat1 to which is added #bj parts of alcohol and #f parts of glycerine1 using #a dram of the solution to each four square inches4 ,a few drops of phenyl1 carbolic or salicylic acid may be added to the solution as a preservative1 and the whole before use well filtered1 while hot1 through linen4 ,the hotter the solution during the pouring on the more evenly the coating will run upon the glass1 and it may be assisted in its flow by careful tilting of the plate4 ,the use of paper strips is dangerous1 and1 notwithstanding the gum1 extremely liable to damage the negative4 ,j ,instead of wax the plate may be dusted over with powdered ,french chalk1 all traces of which are removed before applying the collodion4 ,after such treatment the film is scarcely likely to leave the plate before required4 ,but as a further precaution1 if the edges of two plates be drawn across each other a rough edge will be produced1 to which the collodion coating will adhere tenaciously4--,,trans4 ,reversal of the ,plate1 either collodion or gelatine1 is another method of securing reversed negatives1 and consists simply in inserting the sensitised plate in the dark slide with the uncoated side towards the interior of the camera4 ,a modification of the dark slide may be necessary1 and it will be obvious that the ground glass focussing screen must be reversed1 or the focus corrected after the insertion of the dark slide by shortening the camera a distance equal to the thickness of the sensitive plate4 ,dry plates present great advantages in this method1 but1 in development1 density must be judged entirely by transmitted light1 as the image is formed in1 not upon1 the film4 ,as the rays of light pass through the glass to the sensitive surface1 it is necessary that the uncoated surface be quite clean1 and the glass itself should be perfectly free from bubbles1 scratches1 or other marks4 ,the plate should remain in its levelled position for about fifteen minutes to set and then be carefully removed to a safe and airy position1 gelatine side outwards1 and allowed to dry4 ,this operation will probably take two days2 the hot gelatine layer should be about #c mm4 thick4 ,the negative may then be coated with a toughened collodion 7one or two per cent4 of castor oil added to plain collodion74 ,the plate is placed aside1 and in an hour will probably be dry and ready for the next and final operation4 ,cut with a knife through the film1 take it by one corner1 and1 without pause or hesitation1 strip it from the glass4 ,any necessary retouching should be done upon the gelatine surface after roughing it sufficiently with pumice powder to enable it to take the pencil1 and all such work must be completed before removing the film1 particularly if it has been damaged1 as in such places the colour used in retouching would cause an adherence1 and the film would almost assuredly tear in stripping4 ,upon the quantity of gelatine solution used the nature of the film depends4 ,it should be entirely free from air bubbles4 ,too thick a layer almost always cockles1 and does not lie flat during printing1 in consequence of which portions of the picture will not be sharp in the print4 ,on the other hand1 too thin a layer is extremely awkward to handle in the larger sizes1 and it is preferable to transfer it in a reversed position to a sheet of plate glass coated with indiarubber solution4 ,gelatine ,plates for ,stripping are in the market4 ,in their preparation it is necessary to first coat the glass with a solution of yellow wax in benzole1 or an indiarubber solution1 before coating with emulsion1 such plates being known as strippers in ,america and ,germany4 ,when finished1 the negative is placed1 together with a gelatine film--or 8skin0--in a solution of glycerine and water1 both are withdrawn together1 a squeegee applied to remove the superfluous solution1 and the negative1 with its adhering skin1 placed aside to dry4 ,afterwards the edges of the film are cut through1 and the negative removed from the glass4 ,,stripping ,,the ,,film ,,off ,,gelatine ,,negatives ,,for ,,collotype4 ,in the ,photographisches ,archiv1 ,mr4 ,wilh4 ,otto1 a well-known ,german ,collotype printer1 describes the following process3-- 8,the glass plates are first cleaned by being well rubbed with a solution of caustic potash1 after which they are thoroughly rinsed and polished with tripoli4 ,the next proceeding is to wax them by rubbing one face over with a solution of #ab grains of beeswax to one ounce of ether1 this being applied by means of a piece of cotton or linen cloth saturated with the solution4 ,in polishing off the excess of waxing solution1 care must be taken not to destroy the continuity of the extremely thin and almost invisible film of wax which it is necessary to leave on the glass to ensure the easy and complete separation of the film4 ,some operators prefer to wax the plates by warming them to a temperature somewhat over the melting point of wax1 then rubbing one face over with a lump of the article1 the excess being now polished off with a piece of flannel before the temperature of the glass falls below the melting point of the wax4 ,it may be mentioned that1 before waxing1 it is as well to mark the working surface of each plate by making a diamond scratch in one corner4 8,a small piece of cloth1 moistened with ether or benzole1 is now used to remove all traces of wax from the edges of the plates1 a margin of the width of an inch being sufficient2 and it is well to paint this margin with albumen and to allow it to dry4 ,unless the edges of the plate are entirely free from all traces of wax1 there will be a great probability of the film separating from the glasses at too early a stage1 and adhesion at the edges is made more certain by the use of albumen4 ,a moderately diluted solution of silicate of soda may be used instead of albumen4 8,the waxed side of each glass is now coated with collodion containing a little castor oil2 eight grains of tough pyroxyline and three drops of castor oil to each ounce of mixed solvents 7equal volume of alcohol and ether7 being a convenient preparation4 8,the collodion being dry1 the plates are coated with emulsion4 ,the emulsion flows very badly on the collodionised surface1 but by using a bow made of a piece of sewing cotton stretched across an arc of thin iron wire the difficulty may be readily overcome4 ,the thread is to be drawn over the surface of the plate after the required quantity of emulsion has been poured on1 and it is scarcely necessary to say that the glass should be supported on a levelling stand4 8,plates prepared in this way are developed and fixed in the ordinary manner1 and when a plate is dry it is sufficient to cut through the film inside the edge which has been cleaned of wax1 when the film negative can be easily stripped off4 ,in this case1 however1 the film is very thin1 and it is often desirable to thicken it somewhat before stripping4 ,for this purpose a piece of thin commercial sheet gelatine is taken1 and soaked in water till it becomes quite flaccid1 and this is laid on the negative1 care being taken that no air is enclosed between them4 ,a sheet of wet paper1 or of mackintosh1 is now laid on the gelatine film1 and all excess of water expelled from between the negative and the soft gelatine film by stroking the upper surface of the paper1 or of the mackintosh cloth1 with a squeegee--that is to say1 with a strip of indiarubber set in a wooden handle4 8,it is now easy to remove the paper or the indiarubber cloth which was used to protect the soft gelatine from the action of the squeegee1 and the plate can be set up to dry4 ,when dry1 the film is cut through within the border from which the wax was cleared off1 and the film will separate readily2 but should there be any tendency towards a too early separation1 owing to the contractile force of the fresh thickness of gelatine1 the edges of the plate may be bound with strips of gummed paper40 7,photographic ,news47 ,stripping ,ordinary ,gelatine ,plates4--,any make of dry plate may be stripped by the following method3--,the plate is coated with strong tough collodion upon the gelatine side2 as soon as the collodion has set1 it is plunged into cold water and washed until all greasiness disappears4 ,in the meantime1 a piece of 8flexible support10 as used in carbon printing1 is carefully waxed by rubbing upon its surface a solution of turpentine #adj cc41 beeswax #b gm41 resin #f4e gm4 ,this should be applied evenly by means of a piece of flannel1 the solvent allowed to evaporate1 and the waxed surface polished with a second piece of flannel4 ,the support should then be placed in cold water and allowed to become quite flexible1 in which state it may be used at any time4 ,remove the negative from the clean water1 and place in a bath of methylated spirits #aej cc41 glycerine #c cc41 water #cj cc41 hydrofluoric acid #c cc4 ,an ebonite1 guttapercha1 or lead dish should be used to contain this solution1 with which the fingers should come in contact as little as possible4 ,the film should be watched narrowly1 and when loose upon the glass--but not actually detached--the plate1 still bearing the film1 should be placed in a bath of clean water1 well washed1 and all surface moisture absorbed by careful blotting4 ,take the flexible support from the water in which it has been standing1 and without removing any adherent moisture1 carefully lower it upon the film1 which is still resting upon its original glass plate1 squeegee it into contact with the negative film1 avoiding air bubbles1 place under a weight1 and allow to stand for ten minutes or a quarter of an hour4 ,the film will then be found to adhere to the flexible support1 and may be readily removed from the glass4 ,it should be allowed to dry spontaneously upon the support1 no attempt being made to remove the film until it is 8bone0 dry1 when it will readily part with the temporary support1 remain perfectly flat1 and may be printed from either side with perfectly satisfactory results4 ,should any of the waxing solution remain on the surface of the film1 it may be removed by the careful application of a little turpentine applied on a small linen pad4 ,do not use methylated spirit for this purpose1 as it may cause the film to 8buckle40 ,any stripped films may be conveniently preserved and kept flat between the leaves of a book4 ,the ,powder ,process is one of importance for reproducing and1 at the same time and at one operation1 reversing negatives1 but for some reason is far more resorted to upon the ,continent than in ,england1 where few only have been able to thoroughly master it4 ,failures are usually attributed to changeability in the climate1 but1 although success is by no means uniform1 it is a thoroughly workable process4 ,the basis is a chromated solution of gum arabic1 with which a plate is coated1 dried1 and in a thoroughly dry condition exposed to the light under a negative4 ,the greater the extent to which the light acts1 the smaller will be the amount of moisture the coating of the plate will absorb when exposed to a damp atmosphere4 ,if the surface of the plate be now dusted over with a fine powder1 as drop black1 or graphite1 the greater the amount of moisture certain parts of the film have absorbed1 the greater will be the amount of colour such parts will retain1 and so exactly reproduce the light and shade of the original negative4 ,simple as this process reads1 the difficulties must not be underrated1 and the operator will probably find plenty of opportunity for the exercise of his patience and ingenuity4 ,a consideration of the process as just described will show that a plate which has only been subjected to a short exposure will1 on dusting over and development1 be found to exhibit greater density than one that has received a longer exposure1 a careful adjustment of which will give to the operator great control over the density and characteristics of the reproduced negative1 a power certainly too important to be overlooked4 ,a reliable formula for the preparation of a gum-chromate solution for this process is due to ,dr4 ,leisegang3-- ,rain water #a litre4 ,dextrin or glucose #ej gr4 ,gum arabic #ej gr4 ,honey #aj gr4 ,white sugar #bj gr4 ,glycerine #e gr4 ,cold saturate solution of bichromate of ammonia #ajj gr4 which1 after careful filtration1 is poured over a well cleaned and dusted glass plate4 ,after draining a little by standing on blotting paper1 dry over a spirit lamp1 and place1 while still warm1 under a negative in the printing frame--one minute in the sun1 #aj to #bj minutes in the shade1 is about the necessary exposure4 ,as previously mentioned1 the shorter the exposure1 the denser will be the resulting negative1 a result at variance to any other photographic printing operation4 ,to develop the picture the glass plate is placed1 coated side upwards1 upon a sheet of clean white paper1 then1 with a soft camel-hair brush1 dust over the picture some very finely-ground ,siberian graphite1 working the same backwards and forwards over the plate until the necessary strength is attained4 ,if the picture should develop too quickly1 and take the colour all over1 the cause is under exposure2 should the powder adhere unevenly1 or the picture present a smudgy appearance1 the coating must have absorbed too much moisture1 and must be again warmed before further development4 ,this precaution is particularly necessary during the winter months4 ,if a prolonged development be necessary1 and after continuous dusting a picture lacking in contrast be the result1 it is occasioned by over exposure4 ,on completion of the development the picture should be finally and carefully dusted with a soft brush to remove the superfluous powder1 coated with a thin plain collodion1 and placed in water1 which should be frequently changed1 until it fails to show any trace of yellowness4 ,the plate should be afterwards retouched and varnished4 ,negative ,films have now been before the public some time1 and have been considerably used as reversed negatives by printing with the back of the film in contact with the plate4 ,the four principal varieties are1 in the order of their introduction--#ast1 ,eastman's2 #bnd1 ,froedman's2 #crd1 ,pumphrey's4 ,eastman's ,stripping ,film consists of a substantial paper coated with a layer of soluble gelatine1 upon which is spread a coating of insoluble gelatine emulsion2 they may be exposed in contact with a sheet of glass in an ordinary dark slide in the film carriers or on the roller slide4 ,there are no special precautions necessary in the development1 except that no alum may be used previous to stripping4 ,for use as reversed negatives the ordinary operations are greatly shortened and simplified4 ,a sheet of plate glass is coated with collodion1 allowed to set1 and then placed in a dish of cold water until all greasiness has disappeared4 ,after fixing and washing1 the negative1 still supported upon the paper1 is placed over the collodionised plate in the same dish1 and the two brought out face to face4 ,upon the back of the negative paper place a piece of blotting paper1 cover it with a sheet of oiled paper--as used in copying letters--and apply the squeegee2 place a dry sheet of blotting paper upon the back of the film1 cover it with a sheet of glass or other flat surface1 upon which place a weight4 ,in fifteen minutes the plate may be placed in warm water--about #acj ,f4--and in a short time the paper backing will float off4 ,by gentle washing with hot water remove the soluble gelatine from the film resting upon the glass1 and place the negative aside to dry4 ,it is then complete1 and reversed4 ,froedman's ,films consist entirely of gelatine1 require no stripping1 and may be printed from either side4 ,the film is somewhat difficult to handle in the developer1 and has to be dried by spirit4 ,one feature against their employment in ,collotype is a yellow stain1 which probably arises from the bichromate with which the film is hardened1 and although more apparent where the negative is protected by the rebate of the dark slide1 it undoubtedly pervades the whole picture4 ,pumphrey's ,lifting ,films are the latest and best of a series of films introduced by the same maker4 ,they consist of a basis of paper coated with a waterproof varnish on one side1 upon the other being spread an indiarubber coating possessing considerable adhesive power2 to this is attached the gelatine film proper1 which consists of two layers1 one of plain gelatine1 and the other the sensitive emulsion4 ,the films should be exposed in the camera between two glass plates1 and the spring of the dark slide should be of considerable strength to insure flatness of the film1 and consequent sharpness of the image4 ,the films during development may be treated exactly as an ordinary plate1 the manufacturer recommending ,beach's developer4 ,when in the bath they seem little liable to damage1 and may be handled with great freedom and facility4 ,upon completion of the development1 fixing1 and washing1 the paper backing or support is attached by means of paste to a substantial and smooth card4 ,as a precaution1 not always necessary1 but usually advisable1 against the film prematurely separating from its support1 around the edges gummed paper strips may be attached to the card1 and allowed to extend over the edges of the gelatine film to the extent of #c mm4 ,when dry the film may be varnished1 and afterwards lifted from its support by first cutting through the gelatine and passing the blade of the knife round the edges between the film and the temporary paper backing1 the latter remaining attached to the card4 ,the two are by these means readily separated1 and the resulting negative film may be printed from either side without disadvantage1 and is of sufficient strength to withstand a considerable amount of rough handling4 ,other ,methods of ,reversal4--,there are processes of copying1 usually by first producing a transparency and from that again a negative4 ,if the wet process is used throughout1 a copying camera is essential in both stages4 ,should dry plates1 however1 be used1 the transparency may be produced in the camera and the negative by contact in a printing frame1 or vice versa1 or both may be produced by means of the camera4 ,if the transparency be produced by the carbon process a negative may then be made from it by contact1 and the necessary reversal will be brought about without the use of the copying camera4 ,,chapter ,,viii4 ,,printing ,,in ,,the ,,press4 ,the etching or damping and rolling-up of the ,collotype plate presents difficulties which are greater even than those met with in the preparation of the plate4 ,these remarks also apply with equal force in photo-lithography1 and whoever stops at the preparation of the plates or the photo-lithographic transfer1 and leaves the subsequent operations to be performed by another1 should not be considered either as a collotypist or photo-lithographer4 ,the whole success depends upon a succession of apparent trifles2 many errors it is impossible1 or at any rate difficult1 to rectify1 and great care should be taken that nothing is overlooked1 or from some trivial cause the whole may result in failure4 ,firstly1 remove all adherent matter from the back of the plate1 as the smallest amount of dried gelatine1 particle of grit or other hard matter will suffice to cause the fracture of the strongest glass plate on the first application of pressure4 ,the ,etching or ,damping ,solution in most common use consists of a stock solution of five parts water1 one part liquid ammonia1 three parts glycerine1 and one-tenth part of nitrate of lime4 ,for use add five or six parts of this solution to #ajj parts of water1 sufficient of this being used to well cover the plate when placed in a clean dish4 ,another reliable formula is one litre glycerine1 #fjj cc4 water1 chloride of sodium three grammes4 ,plates may be immersed in these solutions for a time extending from ten minutes to five hours1 or they may be well flooded with it1 wiped off1 and dried with blotting paper4 ,the press having been examined1 oiled1 and put in thorough working order1 the next consideration will be ,fixing the ,collotype ,plate1 which may be performed in several ways4 ,immersing the plate in the etching fluid precludes the old method of cementing it on with plaster of ,paris1 or glue and whitening1 but it may be fixed by adhesion to a bed of glass or a polished iron plate1 or a special and somewhat complicated frame may be procured for securing the thick printing plate by means of adjustable clips secured by screws4 ,should the printing surface be upon a thin glass adhesion alone will be found sufficient1 a few drops of water causing the printing plate to adhere to the thicker glass plate underneath4 ,this method has the disadvantage that it is most difficult to ensure the position of the plate being in keeping with the mask on the frame4 ,should the mask be placed directly upon the gelatine surface of the plate it will not last many impressions without either tearing or causing damage to the surface through the formation of creases or wrinkles4 ,if the picture has to be trimmed without margin1 and mounted--either with or without varnish--the masking is altogether unnecessary4 ,the preparation of the ink and rollers should next be proceeded with4 ,supposing the work in hand to be one of a simple character--say the reproduction of an impression from a copperplate in black--take a piece of the best chalk ink about the size of a hazel nut1 in an unthinned condition1 as supplied to the printing trade1 and with an iron spatula or palette knife spread it upon the inking slab4 ,add one-quarter the amount of middle varnish 7refined and odourless71 one drop of olive oil1 and one or two drops of best ,french turpentine1 incorporate thoroughly by means of the palette knife1 divide1 and apply one-half to the roller4 ,the next operation is the important one of ,distributing the ,ink4--,a really good leather roller1 the handles of which should be encased with easy fitting leather covers1 is most suitable for the purpose4 ,the ink1 by careful manipulation of the roller1 should be gradually distributed over the entire surface of both roller and slab in a perfectly even and regular manner4 ,should any small lumps be observable upon either surface they should be carefully removed with the palette knife and the rolling and distributing again proceeded with1 as on careful attention to this matter the excellence of the resulting print greatly depends4 ,the printing plate being well secured1 its moistened surface should be very evenly dried4 ,this is best effected by means of a roller covered either with fine cloth or washleather1 or a fine soft linen cloth may be used as a substitute4 ,rolling up4--,apply the inking roller with light pressure to the nearest edge of the plate1 and roll backwards and forwards over its surface several times2 an experienced printer will at once perceive the condition of the surface4 ,for the first inking a stiffish ink should be used1 as the plate will not then so readily become dirty4 ,by repeated rolling in different directions1 and what is of equal importance1 with varying pressure1 endeavour to distribute the ink with perfect evenness1 and with a view of producing a clear and vigorous inking1 which will yield a similar perfect impression4 ,it should be remembered that #a4 ,a slow rolling with heavy pressure deposits ink on the plate2 and #b4 ,light and quick rolling removes the ink from the print layer4 ,by modifying the treatment of the plate1 and varying the application of the roller and damping solution1 an experienced printer will demonstrate his power of producing from the same plate flat1 weak1 and unsatisfactory impressions1 or prints as clear and vigorous as may be desired4 ,the first application of the ink having been made with a leather roller1 it should be distributed1 and the half-tones improved by the application of a smooth roller1 preferably of glue composition4 ,without this second inking1 it will be found impossible to produce the highest results in half-tone4 ,the ,second1 or ,composition ,roller1 must be lightly charged with ink considerably thinner than that applied in the first instance1 the remarks concerning the pressure applied to the leather roller applying with equal force in this case4 ,by light1 quick rolling1 the ink is partially removed from the plate1 while heavier pressure and slower movement will deposit ink and strengthen the shadows4 ,when the inking is complete1 the frame with the mask is placed in position4 ,the printing paper1 which may be either strong1 well-sized letter-paper1 thin cardboard1 or the paper known in the trade as 8dull enamel10 cut to a suitable size1 is adjusted over the mask1 and backed with a couple of thicknesses of smooth paper4 ,this again is covered1 with the tympan attached to its frame4 ,push the bed of the press so far under the scraper that the latter1 when pressure is applied1 will nip the plate about one centimetre from the commencement of the picture4 ,this position has to be ascertained by trial before covering with the second or tympan frame4 ,the ,scraper being regulated so that it will give a sufficient pressure1 pass the bed quickly through the press to the extent necessary to produce a complete impression4 ,the length of traverse of the bed during printing can on most presses be regulated by side screws1 or the tympan may be lightly marked4 ,after releasing the pressure1 the bed is withdrawn1 the tympan and masking frames thrown back1 and the printing paper cautiously raised by one corner4 ,it often adheres slightly to the printing surface1 and this is usually an indication of a good plate4 ,the adhesion may1 however1 at times be so strong as to tear the paper1 or1 in the case of enamel paper1 remove the chalk coating4 ,as previously mentioned1 the scraper should be selected of a width somewhat exceeding that of the picture1 but never exceeding that of the glass plate4 ,it may be left plain and moderately sharp1 or covered with leather4 ,damping the ,plate between each impression will usually be unnecessary1 providing a good sample of gelatine is used1 and the damping solution contain a sufficient quantity of glycerine4 ,in cases where the ,collotype plate has been over exposed1 or the subject be one which requires an absolutely white background1 damping between each impression will be absolutely essential4 ,where it is omitted for any length of time1 the whites of the pictures will always be more or less degraded or tinted4 ,should the early impressions not be satisfactory1 patience should be exercised1 and by careful treatment with the roller or rollers1 and care in the damping1 favourable results will often ensue after the first few impressions have been pulled4 ,only from actual damage to the print layer1 or excessive over exposure in the copying frame1 need the plate be placed aside as in a hopeless condition4 ,the beginner should guard particularly against mechanical damages in damping2 drying and rolling4 ,lithographers are inclined to treat the delicate printing surface with the same vigour and energy that they would apply to the more substantial lithographic stone to which they are accustomed4 ,the following directions from 8,kleffel's ,manual of ,photography0 are to be recommended in printing line subjects1 particularly in 8glass0 printing direct from the negative3--8,the chromated layer of gelatine must have been submitted to a sufficiently long exposure to ensure it taking the ink over the whole surface4 ,for the first rolling in of the plate1 the ink should be composed as follows3 ,white wax1 #de parts2 middle varnish1 #e parts2 gum elemi1 #ae parts2 litho ink 7about #es4 per lb471 #bj parts4 8,after the plate has been thoroughly rolled in and blackened1 it must be rubbed with a piece of unbleached muslin1 previously saturated with the following solution3 #cj parts of ammonia and oxgall 7about equal parts71 #cj parts gum arabic1 #ij parts water1 until the picture develops perfectly clear4 ,dry with a clean piece of muslin1 and roll in for the printing proper with ordinary thin copper plate printing ink4 ,plate paper1 similar to that used in printing from the copper plate1 is most suitable40 ,when printing operations are complete1 the rollers1 printing plates1 and inking slabs should be at once cleaned1 as the varnish colours soon harden and create difficulties4 ,cleaning ,leather ,rollers without damaging them requires considerable practice4 ,they are always scraped with a clean knife1 and the operation should be performed in one direction1 to ensure which it is advisable to mark one of the roller handles4 ,leather rollers not in constant use1 before being put aside1 should have their surfaces carefully and thoroughly rubbed over with tallow1 which must1 of course1 be scraped off before the roller is again used4 ,cleaning ,composition and ,indiarubber ,rollers should not be effected by means of scraping1 but their surfaces should be cleaned with turpentine1 applied with a linen rag free from lint4 ,cleaning the ,plates4--,turpentine is used to free the surface from every particle of ink1 and after the thorough evaporation of the spirit1 the plates should be well washed in water to remove all trace of the damping solution1 dried1 and stored in a cool place4 ,it is sometimes a matter of difficulty to remove ink from ,collotype plates that have been printed from1 but a simple method is to pour over the plate--as in developing a collodion picture--some lukewarm water4 ,this will dissolve a thin layer of gelatine1 and enable one to at once proceed with the work4 ,,chapter ,,ix4 ,,finishing ,,and ,,varnishing ,,collotype ,,prints4 ,retouching ,prints4--,under the above heading ,leon ,vidal1 in his work 8,trait ,pratique le ,phototypie10 gives the following directions1 which ,i reproduce from the 8,photographic ,archives40 ,even with the utmost possible care in the preparation of the printing surfaces there will be required in most impressions a little retouching1 if only to hide a few white spots4 ,in large orders this cannot be carried to the extent it is in silver prints4 ,it happens in printing that particles of dust find their way to the plate1 and cause either light or dark spots in the impressions2 the former are covered by touching with ink1 the latter are removed with the erasing knife1 and the white spot resulting from the operation is toned down with ink4 ,this spotting is quickly performed4 ,the paper being dull a colour should be used containing only a small proportion of gum2 it will then be invisible4 ,prints which it is intended to varnish should not be spotted until they have been sized1 unless printed upon a paper already impervious to the varnish4 ,the colour most suitable of all is the actual printing ink thinned with turpentine1 by using which the trouble is avoided of mixing any special colour to match the tone of the impression1 as the two colours are necessarily identical4 ,another advantage gained by adopting this method is that the spotting may be completed before sizing1 as the aqueous solution of gelatine will not cause it to run4 ,for impressions in pure black the lithographic chalk is probably the best medium for correcting proofs1 as the colouring matter will be found to well harmonise with the general appearance of the picture4 ,a blacklead pencil1 on the other hand1 is quite unsuited for the purpose on account of the highly metallic appearance visible wherever the pencil has been applied to the print4 ,retouching or spotting should not extend beyond the removal of light and dark spots2 the correction of larger faults should not be entertained1 but a fresh printing surface produced4 ,faults present in the original negative should be carefully retouched and removed or reduced as far as possible4 ,should the white margins of the picture become soiled by contact with the inky mask or by finger marks1 they may be cleaned with indiarubber ink eraser4 ,the backs of impressions may also be cleaned in the same manner4 ,when copies have to be mounted on cardboard they may be either left with a matt surface or varnished4 ,in the first case1 the edges are trimmed1 and they are then mounted upon the cardboard mounts4 ,if the latter have been previously damped they will retain their flatness4 ,rolling or ,burnishing must not be done until the prints have completely dried1 or the picture may be torn from the mount4 ,sizing and ,varnishing4--,prints to be varnished may be printed on prepared or sized paper1 and in such cases may be at once varnished4 ,if1 on the contrary1 the paper is not sized1 they require a special preparation1 as follows3--,a #aj per cent4 solution of gelatine is laid on with a broad camel-hair brush1 avoiding air bubbles and streaks4 ,after a little practice this operation will be found both easy and rapid4 ,the sized pictures are pinned in pairs back to back on a wooden frame1 to which strips of cork are attached2 when the prints are quite dry the operation of varnishing may be proceeded with4 ,a good varnish1 probably the best for the purpose1 which possesses the double advantage of remaining colourless and setting very hard1 consists of a solution of #ae parts of white 7bleached7 lac in #ajj parts of wood spirit 7vegetable or wood naphtha74 ,on dissolving the shellac it will be found that the solution is clouded on account of the suspended fatty matter1 the removal of which is always desirable2 the varnish will then filter more rapidly and give a more glossy coating4 ,by adding powdered lime three parts of the solution may be decanted clear1 and the remainder may also be used after filtration through felt4 ,or if to three parts of varnish one part of benzine or petroleum ether be added1 the solution will resolve itself into two layers1 and the upper one1 which will contain the fatty matter1 may be poured off4 ,the varnish is best applied by means of a ball or dabber1 care being exercised to avoid air bubbles2 the print is next placed in ,the ,drying-box 7see fig4 #h71 which is a four-sided tin box #a m4 long by #jbe m4 high4 ,a gas-pipe1 perforated with small holes drilled about #f to #h cm4 apart1 runs through the upper part of the box1 the front of which is open to two-thirds its height4 ,a plate1 finely perforated1 divides the upper third from the lower two-thirds1 and forms an inner division1 through the upper of which the gas-pipe passes4 ,the flat perforated division is hinged to allow of being opened for the purpose of igniting the gas4 ,the pictures placed on the bottom of the box dry very rapidly1 while the perforated division prevents the possibility of the ignition of the vapour of the spirit employed4 ,with such an apparatus it is possible to varnish and dry a large number of prints in a very short time4 ,illustration3 ,fig4 #h4 ,sizing may be ,avoided if each picture1 after well drying1 be dipped into the following solution3 ,water #ejj g41 borax #acj g41 white shellac #ajj g41 carbonate of soda #f;g4 ,the borax and carbonate of soda are dissolved in boiling water1 and the powdered shellac then added in small quantities2 when solution is complete carefully filter and allow to cool4 ,the impressions1 two and two1 back to back1 are pinned on frames1 dipped in the varnish1 and afterwards dried4 ,by this procedure a shellac coating is given to the surface only of the print2 there is no gelatine substratum to soften through atmospheric influences1 and so crack and destroy the layer of varnish4 ,in winter the temperature must be kept high1 and the solution should be heated #ae to #bj ,c4 ,parchmentising to a slight degree may also be adopted to close the pores of the paper4 ,add one part by volume of water to two parts of sulphuric acid1 allow it to become quite cold1 immerse the pictures for one second only1 and at once wash in a copious supply of clean water to which has been added a small quantity of ammonia to effectually neutralise the acid4 ,the action of the acid must not be carried too far1 as it is merely necessary to act on the surface4 ,to prevent paper so treated from cockling while drying1 it must be put under pressure or stretched upon a frame2 when quite dry it has to be varnished and dried by heat4 ,varnishing ,enamel ,paper without previous sizing is best done by means of an alkaline solution of shellac prepared as follows3 ,place in a six litre tin flask #a_/b kilo of bleached and powdered shellac1 pour over it #a-a_/b kilo of alcohol and #a-a_/d kilo of strongest ammonia4 ,in the course of a few days the solution of the shellac will be complete1 then add1 with constant stirring1 #b-a_/b kilo of hot water1 and when cold filter4 ,it may be applied to the print with a broad ,blanchard brush1,k and left to dry in a horizontal position4 ,the prints may also be floated on the varnish for about half a minute1 and then suspended to dry by means of clips4 ,after a few minutes have elapsed a piece of blotting paper should be applied to the bottom edge to absorb the superfluous varnish4 ,k ,made as follows3 ,take a piece of glass1 say #bj cm4 long by #f or #g cm4 wide1 and a piece of swansdown calico the same width as the glass but only #f cm4 long1 fold this over the one end of the glass1 #c cm4 being on each side1 and bind round with thread or spring on a rubber band4 ,rolling or ,burnishing must on no account be attempted until the mounted prints are perfectly dry1 otherwise they may be seriously damaged or even completely torn from the mounts4 ,,chapter ,x4 ,,other ,,collotype ,,processes4 ,the ,artotype ,company1 of ,new ,york1 which has acquired ,obernetter's process1 proceed on somewhat different lines to those laid down in this work1 and an abstract of their proceedings is here given as interesting to those about to experiment4 ,according to ,bachrach1 8,photographic ,archives1 #ahgi10 p4 #ff1 they proceed as follows3-- ,illustration3 ,fig4 #i4 ,plates coated with ,husnik's silicate of soda substratum are dried rapidly in a box heated to #fe ,c4 ,this causes the solution to coagulate1 the plates are dried in half-an-hour1 and as it adheres with great tenacity to the glass plate1 the latter may be at once coated with the chromated gelatine solution1 or it may be kept till the next day4 ,before the second coating is applied the plate is well washed and allowed to dry spontaneously4 ,the drying-box is of wood1 #b-a_/b feet square and #e feet high1 the entire front being a large door1 as shown in the sketch 7fig4 #i71 and the bottom a flat water tank about four inches deep fitted with two pipes1 one to allow the escape of steam1 and the other of use in filling the tank with water4 ,it may be heated by means of gas or a petroleum lamp4 ,after the bottom of the box has been accurately levelled1 it is covered with a few sheets of blotting paper1 on which are placed the albumenised plates4 ,occupying the upper part of the box are adjustable racks1 on which other plates are dried4 ,the box is heated to #hb ,c41 the plates are levelled in their places1 and just sufficient hot chromatised gelatine solution poured on each to spread up to the edges--not more4 ,the ,artotype ,co4 takes one-third each of gelatine1 isinglass1 and the so-called ,magdebourg isinglass4 ,plates are allowed to remain in the drying-box about #bj to #cj minutes1 during which time the door must not be opened1 and particular importance is attached to the high temperature1 reaching even to #ic ,c41 at which the drying is completed1 as it is considered by these means printing plates of much finer grain are obtained4 7,the ,author believes the temperature given is much too high1 as it would be sufficient1 without exposure to light1 to bring about a partial decomposition47 ,when dry1 the plates may at once be printed under the negative4 ,to etch the plate it is immersed in a solution of #e gr4 alum in #a litre of water1 rinsed1 allowed to dry1 and put in a bath consisting of #aej ccm4 of water1 #a litre of glycerine1 #cjj ccm4 of ammonia1 #cj g4 nitrate of lime4 ,plates that have been exposed under the negative too long are treated with a solution of #bj parts of ammonia1 #bj parts of glycerine1 and one part of ,venetian turpentine2 with this they are flooded4 ,the remainder of the process is very similar to that already described4 ,seignior ,carlos ,relvas4--,vidal publishes the following method of procedure as that adopted in the studio of this eminent ,portuguese amateur collotypist1 where it was introduced by ,jacobi3--,very thick glass plates1 finely ground on one side1 are used2 they are cleaned with nitric acid1 and rinsed in distilled water4 ,the drying box used is provided with iron bars1 fitted with adjustable screws for the purpose of accurately levelling the plates4 ,midway between the top and bottom of the box is an iron plate1 underneath which are fitted gas jets4 ,the doors by which access to the box is gained for the plates consists of very fine wire gauze1 allowing the escape of steam1 but preventing the access of insects4 ,after a thorough cleansing1 the plates are levelled on the adjusting screws1 allowed to thoroughly dry1 and then coated on the ground side with the following solution-- ,white of egg #afj ccm4 ,bichromate of potassium #h g4 ,distilled water #dhj ccm4 ,glycerine #af drops4 ,to which is added sufficient ammonia to give the liquid a pale yellow tint1 somewhat less being used where a hard negative is to be employed4 ,this substratum is filtered1 and the plates afterwards coated and placed upon the levelling screws in the drying box1 which is heated to a regular temperature of #dj ,c4 ,in about two hours the plates will be dry1 and are then placed1 coated side downwards1 upon a black cloth1 the back of the plate being exposed to diffused light for half-an-hour4 ,it is again placed in the drying box1 and the second coating1 as follows1 applied-- ,gelatine #bg g4 ,water #djj ccm4 ,bichromate of potassium #i g4 ,preparation ,a #ae ccm4 ,preparation ,b #ae ccm4 ,ammonia a few drops4 ,the preparations ,a and ,b are as follow3 ,a4--,chloride of sodium #a g4 ,water #ejj ccm4 ,b4--,sulphate of alumina #a g4 ,water #ajj ccm4 ,to each square decimetre of surface should be allowed #b ccm4 of the above solution4 ,the plates are replaced in the drying box1 which is heated to #de or #ej ,c4 ,they should be dry in three hours1 and are then ready for printing under a negative in the copying frame4 ,they are afterwards well washed in filtered water1 and allowed to dry spontaneously in a dust-proof situation4 ,in two or three days the printing may be proceeded with1 the surface having been softened by allowing the plate to stand for seven hours in the following solution-- ,glycerine #ejj ccm4 ,distilled water #bjj ccm4 ,preparation ,c #ajj ccm4 ,,preparation ,c4--,sulphate of magnesia #ej g4 ,distilled water #ejj ccm4 ,all solutions are filtered through flannel4 ,from the face of the plate the superfluous moisture should be removed with a sponge4 ,a very thick glass plate is fixed to the face of a lithographic stone by means of glue and whiting1 and adhesion is secured between the face of the thick glass plate so fixed and the back of the ,collotype plate by means of a few drops of water4 ,the whole1 so arranged1 is placed upon the bed of the press4 ,should the prints lose their contrast while the printing is in progress1 they are lightly sponged over with a sponge dipped in the last-mentioned solution4 ,if this fails to produce sufficient effect1 the plate is first washed with turpentine1 and then with the glycerine solution4 ,care should be taken to prevent the two liquids becoming mixed on the plate1 to prevent which different sponges and drying cloths should be used4 ,,chapter ,,xi4 ,,failures ,,in ,,collotype4 ,,in ,,the ,,preparation ,,of ,,the ,,plates4 ,air bubbles in the albumen substratum4 ,these must either by filtration or by the aid of a piece of paper be carefully removed from the solution before it is applied to the plates4 ,the latter must be well cleaned and dusted1 and freed of emery powder if they have been re-ground4 ,to ,prevent ,dust or other matter rising from the edge of the plates by capillary attraction while standing1 they should be allowed to rest on clean blotting paper1 and preferably on one corner only4 ,coating ,plates4--,great difficulties are experienced by the beginner in coating the plates with the chromated gelatine4 ,he seldom knows beforehand the exact quantity required1 or the temperature of the solution4 ,the latter ought to be ascertained1 as it is an important factor in the thickness and flow of the coating2 with a solution only just warm it is impossible to apply a very thin coating1 while the hotter the gelatine the thinner the layer4 ,considerable dexterity and judgment are necessary to spread an even layer of the requisite thickness1 which is a matter most essential to success1 but1 unfortunately1 only to be mastered by actual experience4 ,plates are not unfrequently spoiled by inclining them while conveying them to the drying box1 as in this way the coating is frequently rendered uneven4 ,all solutions must be carefully filtered1 and the plates freed entirely from dust4 ,the drying box1 particularly the lid1 must be carefully dusted and cleaned1 but not immediately before use4 ,other necessary precautions have been pointed out while describing the preparation of the plates4 ,by strictly adhering to the rules laid down it will be found possible1 after a certain amount of practice1 to avoid the pitfalls here enumerated1 while with regard to faults in the plates1 there only remain to be mentioned the consequences of drying at too high a temperature4 ,thick ,films are extremely liable to fly off the glass and damage its surface1 if dried at too great a heat4 ,the thicker the film the lower should be the temperature of the drying box4 ,thin ,films1 dried at too high a temperature1 even without exposure to light1 present a brown appearance1 their sensitiveness is impaired1 and they take too much ink over their entire surface4 ,,failures ,,in ,,printing4 ,it is generally an advantage to work the press in a cool and somewhat damp apartment4 ,breakage of the ,plate4--,notwithstanding its thickness1 the glass plate sometimes flies to pieces on pulling the first impression4 ,if the plate and its foundation are perfectly level the breakage must arise from the presence of some foreign substance having found its way between the two surfaces4 ,this may occur from such a trivial matter as a grain of sand1 perhaps introduced between when moistening the under side of the plate to secure adhesion4 ,or traces of chromated gelatine may be found attached to the under surface of the plate1 either of which causes is quite sufficient to account for a breakage with even moderate pressure4 ,in ,collotype the pressure need not be by any means so heavy as in lithographic printing2 it should be evenly distributed1 and may be moderated by placing the stone or glass plate1 or whatever the ,collotype plate may be attached to1 on some comparatively elastic bedding1 which may consist of several layers of printing paper1 thin felt1 thick indiarubber sheeting1 or linoleum1 any of which may be used4 ,spotted ,impressions4--,the plate yields unsatisfactory copies covered with white spots resembling drops of water4 ,this most frequently occurs at the commencement of the printing1 and is nearly always caused by uneven damping of the surface4 ,old plates which have been dried very often give perfect negative impressions at first4 ,in such cases1 after the removal of the ink by turpentine1 soak the plate for a quarter of an hour in water1 to which has been added a little glycerine and ammonia 7see 8,etching ,fluid074 ,dry the plate with a clean roller covered with cloth or chamois leather--or1 as a substitute for the roller1 a soft linen cloth may be used--and again roll in with ink which has been thoroughly well distributed on the inking slab4 ,too ,much ,ink is taken by the plate over the whole surface1 and notwithstanding slow or rapid rolling1 it refuses to leave the high lights4 ,cause--over-exposure in proportion to the thickness of the layer1 which is probably too thin4 ,in such cases washing with dilute solution of ammonia will often improve matters4 ,another proceeding to be recommended in the case of a plate taking too much ink is to remove all ink by means of a sponge damped in water containing a little petroleum--not benzine or turpentine--and afterwards wash the plate with a sponge containing glycerine and water4 ,it is then ready for immediate printing from1 and ought to give about #bjj copies without further damping if the press be in a moist situation4 ,loss of ,half-tone arises from the print layer becoming too moist1 when the more delicate half-tones fail to print4 ,dry with blotting paper1 and immerse for five minutes in a bath of alcohol2 this will take up the water1 and the succeeding impressions will be greatly improved4 ,uneven ,inking4--,it sometimes occurs1 particularly in pictures which should show a white ground1 that the latter takes more ink in one part than another4 ,this usually arises from an unequal thickness of the sensitive coating4 ,the plate will take most ink where the coating is thinnest1 and for this fault there is no remedy4 ,ink ,refused by the ,plate4--,sometimes1 after a few impressions have been pulled1 the plate refuses to properly take the ink1 from the layer being too thick and having been too freely moistened4 ,further damping should be discontinued and a thinner ink used1 which will better take upon the deep-lying shades4 ,this fault will be found most pronounced in the cases of written or printed titles to pictures1 and other cases exhibiting extremely disproportionate action of light4 ,therefore1 when there is writing to a picture1 it should be shaded somewhat during printing in the printing frame1 or if the contrast be very violent it may fail to print entirely4 ,flat ,prints4--,after a number of satisfactory prints have been produced the succeeding ones become flat1 this fault will be especially noticeable with thin layers devoid of isinglass1 and in cases where the negative has been too flat and lacked contrast4 ,dampen more frequently with dilute ammonia and glycerine4 ,paper ,adhering to the ,gelatine--,those layers which yield the best and most brilliant impressions1 showing plenty of contrast1 which have been fully printed under a vigorous negative1 most often exhibit a disagreeable tendency to adhere to the paper in the high lights4 ,the greater the proportion of isinglass present in the film the more will this fault manifest itself1 particularly with an enamel paper4 ,an application of a diluted solution of ox-gall to the film1 the use of a thick well-sized or glazed paper1 lighter pressure while printing1 and less frequent damping will all tend to diminish this evil4 ,layers of this nature are extremely liable to damage1 and the adhesive portions will soon suffer unless the greatest care is exercised4 ,ink ,remains upon the ,plate4--,through too light or uneven pressure it sometimes happens1 especially when using a stiff ink1 that the latter will1 after the impression has been pulled1 partially adhere to the darkest portions of the printing surface1 particularly on the edges of plates deeply copied4 ,if this fault is not corrected at once1 and the printing allowed to proceed1 these portions giving a light1 faulty impression will gradually increase in size1 and the corresponding portions of the ,collotype plate gradually darken4 ,when first observed the whole plate must at once be cleaned with turpentine and again rolled up with thinner ink1 a greater and perfectly even pressure being applied4 ,small faults of this nature occurring on the edges of the plate can be corrected after each faulty impression by means of a small piece of sponge moistened with gum water or with a turpentine rag4 ,displacement of the ,paper under the scraper will create a double impression1 and sometimes wrinkles1 the latter invariably leading to the destruction of the plate4 ,by adopting the use of the bridge now used in conjunction with most ,collotype hand presses1 this fault is avoided1 as the paper is only in contact with the printing surface immediately under the scraper4 ,,chapter ,,xii4 ,,investigations ,,on ,,collotype4 ,august ,albert,l is of opinion that it is by no means a matter of indifference whether bichromate of potassium or bichromate of ammonia is used in the preparation of the ,collotype plates2 on the contrary1 he believes that the latter salt materially conduces to interruptions in printing1 especially in unsettled weather4 ,the results of his experiments with the two salts in the ,collotype process1 and of their behaviour in combination with different sorts of gelatine1 are as follows3-- ,to #ajjj cc4 of water are added ten drops of a saturated solution of chrome alum2 this mixture1 after having stood for a quarter of an hour1 must1 if shaken up1 show an opalescent appearance1 and a slight milky turbidity2 if too much chrome alum has been added1 the water acquires a greenish colour4 ,the gelatine is now added1 and1 for about fifteen minutes1 kept at a temperature of #acd1 when the chrome salt is added1 stirring all the while1 and the temperature of the water bath raised to #aej to #afj4 ,the temperature and time must strictly be adhered to4 ,the jelly thus prepared should be kept at least ten hours in a solidified state previous to using4 ,l ,this experimentalist has evidently been confused with the late ,joseph ,albert1 of ,munich1 by some writers4 ,it may be mentioned that ,joseph ,albert1 whose business is still carried on by his widow1 was father of ,dr4 ,eugene ,albert1 known in the photographic world for his orthochromatic collodion emulsion4 ,august ,albert1 of ,vienna1 is of another family4 ,hard ,gelatine4--,plates prepared with this1 show after drying1 a shiny1 transparent film1 more or less according to the quality4 ,such plates give hard prints1 and are soon used up in printing1 the finest and even the middle tints becoming weaker1 and the shadows gradually coalescing1 specially in the case of short exposure and very dense negatives1 and they are generally useless after a few impressions have been taken4 ,if ammonium bichromate is used1 together with hard gelatine1 then1 as a general rule1 it is impossible to obtain more than one or two prints from each plate4 ,by washing the gelatine1 these inconveniences are not at all removed1 no matter which of the two salts has been used4 ,soft ,gelatine4--,if this is prepared with potassium bichromate1 then the plates will have a dull but rough and untransparent film1 which will be found very unserviceable for printing1 as the prints will lack vigour2 the high lights will tone1 and the whole picture appear blurred4 ,if1 however1 ammonium bichromate is used in conjunction with soft gelatine1 the plates will also have a dull appearance1 but though they work somewhat better than those prepared with potassium bichromate1 they will not be of sufficient durability1 the finer tones soon disappearing during printing4 ,therefore1 neither hard nor soft gelatine are suitable for ,collotype work1 as the printing operations are rendered more difficult4 ,if both sorts are mixed1 the results will be somewhat better1 but not like those obtainable with middle hard gelatine1 which must be accepted as the most suitable kind for ,collotype work4 ,middle ,hard ,gelatine1 manufactured by ,ferd4 ,friedr4 ,creutz1 absorbs five times its own weight of water at #ff1 without signs of disintegration after standing therein for thirty-six hours4 ,if prepared with it and with chemically pure potassium bichromate1 the plates after drying have a beautiful matt surface1 from which long numbers can be printed without any falling off of the half tints1 and1 if the printing is done carefully1 even the details in the shadows will be maintained to the last4 ,this bichromated gelatine requires also only a very small amount of re-damping1 reproduces faithfully the character of the negative1 and the jelly can be used even after a period of four days4 ,if1 however1 the work in hand requires a harder bichromated gelatine--as1 for instance1 reproductions of black and white--then the addition of a small quantity of ammonium bichromate will have the desired effect2 in some cases equal quantities of the bichromates of potassium and ammonium4 ,if ammonium bichromate is used instead of potassium in conjunction with middle hard gelatine1 then the plates will acquire a shining1 transparent coating1 the manipulation of which is very difficult in printing1 and which work too hard1 being serviceable1 at any rate1 for reproductions without half-tint4 ,if1 however1 the middle hard gelatine is washed before use1 it will give1 when mixed with the chromic salt1 transparent films of insufficient durability4 ,middle hard gelatine should therefore be used unwashed for ,collotype work1 and mixed with chemically pure potassium bichromate4 ,the ,production of ,grain in ,collotype plates takes place in the last instant of drying the plates in the drying-cupboard2 it depends entirely upon the larger or smaller quantity1 and the consistency of the bichromated gelatine used4 ,if the latter is of good quality1 all artificial means for the production of grain are not only superfluous1 but also disadvantageous4 ,a larger addition of chrome salt generally gives rise to the crystallisation of the salt2 chloride of sodium produces plates highly sensitive to moisture1 but no grain2 a larger addition of chrome alum gives plates which will lack vigour1 and the manipulation of which1 during printing1 will be difficult1 as they often will require an 8after-etching10 so that even printing is made impossible4 ,to test the suitability of gelatine for ,collotype work1 two small portions of the gelatine to be tested may be made up1 adding chemically pure potassium bichromate to the one1 and ammonia bichromate to the other1 and a plate prepared with each solution4 ,if both plates show a dull and untransparent coating1 this indicates that it is a soft gelatine2 if1 on the contrary1 both plates appear glossy and transparent1 then the gelatine is hard4 ,should it1 however1 be middle hard1 then the dried film prepared with potassium will be dull1 but not rough2 that with ammonia1 however1 shiny and transparent4 ,,chapter ,,xiii4 ,,collotype ,,in ,,natural ,,colours4 ,a short chapter may be devoted to the various suggested processes for producing ,collotype in natural colours1 with which are associated the names of ,vidal1 ,albert1 and ,obernetter4 ,to give a complete resume is altogether impossible1 as up to the present time the inventors have only published their method of procedure with very considerable reservations1 and notwithstanding the fact that a great deal has been written and published in current literature on the subject1 little is actually known4 ,the methods of ,vidal and ,albert are essentially alike1 both being founded upon an opti-chemical basis4 ,by careful registration and printing from three ,collotype plates1 representing fragments of the same subject upon one sheet of paper1 and making use of inks corresponding with the three primary colours1 a total effect should be produced which ought1 theoretically1 to resemble the coloured original4 ,in preparing the three negatives for reproducing the three colour plates a special mode of procedure must be adopted4 ,each of the three negatives must give a resulting ,collotype plate capable of retaining varying amounts of ink when rolled up1 according to the predomination in the original of one or the other of the primary colours--red1 blue1 or yellow4,m ,this is effected in the production of the negative for the red plate1 by making the exposure through a green glass screen1 while the negative intended to produce the plate from which the yellow is to be printed is exposed through a screen of violet4 ,m ,pictures produced in the three primary colours are extremely crude4 ,dr4 ,vogel has proposed a large number of negatives1 using for their production sensitisers corresponding with every region of the spectrum4 ,for example--,napthol blue for red1 cyanin for orange1 rozin for yellow1 and fluorescein for bluish green1 the ordinary sensitiveness of the plate being sufficient for blue and violet1 the latter1 however1 being exposed through a yellow screen4 ,the images thus obtained are printed from lithographic stones or ,collotype plates1 each of which is printed in a colour complimentary to that part of the spectrum to which the particular plate was sensitive4 ,the greater the number of separate images produced in this way the more complete will be the reproduction of the various shades in the original1 and the more pleasing the resulting print4 ,the green screen allowing to pass so few chemically active rays the exposure has to be prolonged to such an extent that gelatine bromide dry plates stained with eosine must of necessity be used4 ,obernetter's method is entirely different1 depending more upon mechanical assistance of a non-photographic character in the production of the unlimited number of negatives he uses for producing his printing surfaces1 and the results more closely resemble those of chromo-lithography4 ,what particulars ,obernetter himself has from time to time communicated are here given4 ,he first produces1 by the dusting-on process1 as many copies of the original negatives as there are colours to be reproduced4 ,the negative intended to produce the plate from which the blue will be printed is obtained by a long exposure and only slight dusting of the reproduced negative4 ,that intended to reproduce the plate for the non-actinic colours--yellow or brown--should be correctly exposed and dusted in2 while that intended for the red should be subjected to a shorter exposure and more vigorous dusting4 ,by retouching1 the densities of the various negatives may be modified by strengthening them in parts1 other portions are stopped out1 and the negatives so manipulated that they will produce plates capable of giving impressions--when printed in their proper colours--giving a facsimile reproduction of the original work4 ,much will depend upon the artistic qualifications of the operator1 who may1 by extending the number of plates1 finally produce copies of considerable artistic value4 ,hsch1 of ,munich1 has patented a process in which the same result is attained in a somewhat different manner4 ,a negative is produced1 and from that a ,collotype plate from which a number of impressions are taken equal to the number of printing desired or necessary in the finished chromo-collotype picture4 ,each print has certain portions painted over in a neutral tint1 such portions depending upon the colour of the ink in which it is intended to print the corresponding plate4 ,other portions are stopped out white in the print1 or black in the negative1 and from the prints so treated a set of negatives are taken2 these are utilised for the production of a set of ,collotype plates1 which1 printed from in suitable colours1 yield impressions of great excellence4 ,,chapter ,,xiv4 ,,magic ,,prints4 ,to ,professor ,husnik 7to whom collotypists are greatly indebted for so many unselfish publications71 we owe the origination of this interesting method of producing 8magic0 prints4 ,it is founded on the reaction well known to chemists that two substances1 each colourless in itself1 when mixed1 enter into fresh chemical combinations and produce other substances of intense colour4 ,herschel and ,hunt made use of many of these reactions1 both to develop the invisible image1 and to give to others1 already visible a more agreeable colour or tone4 ,impressions other than those in fatty ink may be obtained from the ,collotype plate--as in the process patented by ,edwards--by means of colour1 soluble in water1 to which the addition of a small amount of gum has been made4 ,in such cases it will not be those portions of the layer which have been rendered insoluble by the action of light which will give the impression 7as it would if ink were used7 but on the contrary1 the unexposed parts1 or those which remain soluble4 ,on this account the resulting print will be a negative1 and to obtain a positive1 the printing must take place under a positive4 ,if a ,collotype plate so produced be damped with a linen rag which has been moistened with an aqueous solution of a salt readily absorbed by gelatine1 and which will produce in combination with a second solution an intensely coloured compound 7the use of the ink roller being entirely omitted71 the impression on the printing paper will be almost or even entirely invisible until brought in contact with the second solution1 when the picture will be immediately developed and rendered visible4 ,for instance1 dampen the plate with an aqueous solution of red prussiate of potash1 surface dry it1 print upon paper1 allow to dry thoroughly1 and place upon a solution of protosulphate of iron1 when the picture will immediately appear of an intense blue colour4 ,solutions of bichromate of potassium or nitrate of silver will produce brown images2 the former developed with extract of logwood1 alazarine or sugar of lead1 all produce different colours4 ,not only is this process interesting1 applied in the manner already described1 but it is of use in calico printing4 ,care must however be exercised in the selection of a suitable solution for damping the plate1 as many salts would tan the gelatine layer1 and such are of course utterly unsuited for the purpose4 ,among the mordants in common use1 salts of tin1 alum1 iron1 c41 may be mentioned as exercising a hardening influence upon gelatine1 and therefore useless for moistening the layer4 ,there remain1 however1 many others which produce no damaging effect upon the plate1 and at the same time produce useful colours4 ,,chapter ,,xv4 ,,photo 8,,glass0 ,,printing4,n ,n ,this process has never been practised in this country so far as ,i am aware4--,,trans4 ,there remains to be mentioned another variation of the ,collotype process known under the above vague title1 the distinctive characteristic of which method of preparing the plate is that the negative is taken upon a sheet of glass sufficiently thick to stand the necessary pressure in printing when converted direct into a ,collotype plate4 ,after the completion and drying of the collodion negative it is coated upon the film side with the chromated gelatine solution1 dried in the drying-box1 laid face downwards upon a black velvet surface1 and exposed through the back of the glass4 ,the first publication of this method of preparing plates emanated from the ,state ,printing ,works at ,berlin1 and the following is an outline of the method there practised2 it is scarcely necessary to state that it is only available for line subjects4 ,the collodion used in the preparation of the negative should be one capable of producing clear1 hard negatives entirely free from fog2 probably some modification of the dark slide may be necessary to enable it to receive a plate of sufficient strength to stand printing from4 ,the collodion negative being completed it is flooded with the chromated gelatine as applied to ,collotype plates1 dried1 and exposed through the negative until the print layer has assumed a dark brown colour2 it is well washed in cold water and damped before printing by an application of gum water containing a little ox-gall2 this is done to facilitate the production of perfectly clear impressions4 ,the same end may be attained by the application of dilute ammonia and glycerine4 ,the author has experimented for several years in the same direction with the object of producing heliographic printing plates in copper1 for which purpose this method of producing reliefs in gelatine is well suited4 ,from the negative printing plate described1 which is treated in all respects as a ,collotype plate1 impressions may be taken upon transfer paper1 and transferred to stone or zinc4 ,before coating the negative with the chromated gelatine the plate should be allowed to dry4 ,in consequence of printing from the back the lines will always be slightly wider than the original1 to meet which difficulty ,brandt has proposed putting the negative1 when fixed and washed1 but still wet1 into a weak solution of chromated gelatine1 which will1 if a suitable collodion has been employed1 entirely penetrate the latter4 ,this variation appears worthy of commendation2 it is1 therefore1 here given in the abstract3--8,having produced a negative in the usual manner1 on a plate which has been lightly but carefully albumenised1 and having fixed and washed the same1 it is placed for five minutes in a solution prepared as follows3 ,allow #de parts of gelatine to swell in water1 and pour off the surplus1 add #ej parts of distilled water1 and apply sufficient heat to completely liquify the gelatine1 adding a solution of #ee parts of bichromate of ammonium in #ajj parts of water1 and heat again to #fj ,ramur4 ,with plates of large size the solution may be poured over the plate1 and it may be necessary to repeat this operation several times to ensure an even and sufficient coating4 ,immediately previous to the application of the chromated layer the negative should be rapidly washed over with warm water4 ,a sufficient quantity of the chromated solution must be allowed to remain upon the plate1 and the latter warmed in a horizontal position over a spirit lamp4 ,when steam arises the plate has to be held in a perpendicular position for a minute1 restored to its horizontal state1 and again warmed until the coating of the plate is quite dry1 care being taken that at no time the plate is so heated that it becomes unpleasant when placed upon the hand4 ,place the plate face downwards upon a black support1 print until the fine lines are plainly visible1 when the plate may be washed and further treated as in ,collotype40 ,,chapter ,,xvi4 ,,allgeyer',s ,,collotype ,,process4 ,half-tone ,negatives must be softer1 and possess more half-tone than requisite for silver printing4 ,when examined by transmitted light1 they should appear clear in the shadows1 and not too dense in the half-tones4 ,line ,negatives4--,negatives for the reproduction of line subjects need not possess the absolute opacity requisite for silver printing1 but the lines should be clear glass1 entirely free from fog or deposit4 ,stripping the ,negative4--,the fixed and washed negative is flooded over with a solution of gum arabic in water 7#a to #bj71 to which has been added a few drops of a solution of chrome alum 7#a to #fj74 ,allow to dry1 retouch with lead pencil1 and edge with tallow to prevent overflow1 place upon a levelling stand1 warm moderately1 and coat with a solution of gelatine #ajj parts1 glycerine #ae parts1 alcohol #ajj parts1 water #djj parts1 allow to set1 and place against a wall to dry1 the coated side outwards1 the plate standing upon clean blotting paper4 ,the operation of drying will probably take a day or two1 and when quite complete1 it is again coated with collodion1 and again dried4 ,after allowing to remain in a damp place for two or three hours1 cut around the edges with a knife1 and strip off the film1 which may then be printed from either side1 and after use may be stored in a book1 the leaves of which consist of smooth paper4 ,reproduced ,negatives4--,coat a plate with a solution of gum arabic #ej parts1 dextrine #ej parts1 honey #aj parts1 sugar #be parts1 glycerine #e parts1 bichromate of ammonium #ae parts1 ammonia #ej parts1 water #a1jjj parts4 ,after drying1 expose under a negative1 dust over with graphite1 coat with plain collodion1 and wash in clean water until all yellowness disappears4 ,substratum4--7#a47 ,water #cjj parts1 white of egg #cjj parts1 ammonia #ej parts4 7#b47 ,water #cjj parts1 gelatine #aj parts1 bichromate of potassium #aj parts4 ,filter both solutions1 and mix1 taking care that the temperature never exceeds #cb ,c42 pour upon glass plates heated to #cj ,c41 and dry at a temperature of #bb ,c4 ,after thoroughly cleaning the back of the plate1 place1 face downwards1 upon a black cloth1 and expose to light through the glass till the coating becomes brownish4 ,to test if sufficiently exposed1 dampen a portion of the film with the finger1 scratch with the nail1 and the scratch should stand out perfectly sharp4 ,the intermediate layer is to ensure the better adhesion to the glass of the print layer proper1 and to facilitate the retention of moisture while printing4 ,it consists of gelatine #ajj parts1 water #a1ejj to #a1hjj parts1 alcohol #aej parts1 glycerine #e parts1 bichromate of potassium #e parts4 ,this is spread over the substratum1 allowed to dry1 and exposed to diffused light1 or allowed to stand for twenty-four hours1 well washed1 and allowed to dry spontaneously1 after which it may be kept for weeks4 ,the ,print ,layer consists of water #a1ejj parts1 gelatine #ajj parts1 bichromate of ammonium #cj parts1 complete solution being effected by means of a water bath2 the drying box heated to #de to #ej ,c4 ,place the levelling stand upon a sheet of white paper1 carefully dust and accurately level the glass plate1 and coat1 using #cj ccm4 of solution to cover #be #ce cm4 of surface1 avoiding any overflow of solution4 ,the ,washing ,water used after printing in the copying frame should not exceed #bb ,c4 in the summer1 or fall below #aj to #aa ,c4 in the winter4 ,washing should be continued until the film is free from colour1 and a final rinse should be given under a rose4 ,allow to dry slowly4 ,etching ,solution4--,water #ejj parts1 glycerine #ejj parts1 chloride of sodium #ae parts1 or hyposulphite of soda #ae parts4 ,rolling ,up4--,if the picture take too much ink1 wash off with turpentine1 carefully wipe with a cloth1 and continue the etching4 ,if it take little1 wash off the ink with etching fluid1 and place in a hardening solution of chrome alum #a part1 water #f parts1 wash1 dry1 and once more etch for a quarter of an hour4 ,varnish for ,prints4--,bleached shellac #ajj parts1 dissolved in alcohol #cjj parts1 adding ammonia #cjj parts1 further adding1 with constant agitation1 #fjj parts of boiling water4 ,,chapter ,,xvii4 ,,practice ,,of ,,photo-,,lithography4 ,in photo-lithographic operations1 quite a different set of conditions has to be considered as compared with ,collotype4 ,an explanation is1 of course1 not far to seek1 as both the chemical and physical properties of the lithographic stone and the exposed chromated gelatine layer are so extremely different4 ,to the better understanding of the operations1 the composition of the lithographic stone and the principles underlying the process may be first considered4 ,senefelder is a name inseparably connected with lithography1 as it was he who1 after a continuous and laborious research1 discovered the remarkable properties of the ,solenhofen limestone1 who thoroughly worked out the conditions under which printing with fatty inks could be carried out1 and so thorough and conclusive were whose researches that the process as now practised may be said to be actually identical with those of the discoverer4 ,he was by inclination a dramatic author1 but failing to find a publisher for the productions of his brain1 he conceived the idea of publishing his own works4 ,at a printer's he acquired the necessary knowledge to perform the work1 but lacked the funds to purchase press or type4 ,he then turned his attention to copperplate1 made many unsuccessful attempts with an old one he possessed1 and when that was unfit for further experiment1 extended his operations to the pewter plates of his mother's dining service1 but still without success4 ,by accident1 his next experiments were made upon a stone procured from ,cellheim 7,solenhofen71 and which up to the present had served him as a slab for his ink4 ,for want of paper and ink to write a domestic account for his mother1 he casually used the surface of this stone in lieu of paper1 using as an ink a mixture of soap1 wax1 and soot1 with the intention of copying upon paper later on4 ,when about to clean the slab1 the thought flashed across his mind why not etch the stone with a dilute solution of nitric acid8 ,the experiment was tried1 and succeeded beyond expectation4 ,upon this simple accident has been built up the whole process of lithography4 ,it was only in #agii1 after a prolonged and severe struggle1 that he was granted protection for his art in ,bavaria4 ,the acid etches away a very thin layer of the unprotected stone1 while the writing is not attacked1 but left slightly in relief4 ,senefelder--first with a dabber1 and later with a piece of wood covered with cloth--inked in the writing1 and so produced impressions1 the earliest of which were sheets of music4 ,the etching of a lithographic stone bearing a drawing or transfer in lithographic ink has a twofold action1 each of which facilitates the printing4 ,in addition to the slight relief already mentioned1 as resulting from the application of the acid1 the latter forms upon the surface of the stone1 where attacked1 nitrate of calcium1 which resists and refuses the fatty ink upon the surface of the roller1 and if the surface of the stone be kept constantly damp it becomes possible to roll up the drawing1 to which alone the ink adheres4 ,lithographic stones do not consist merely of carbonate of lime1 but contain also silica1 alumina1 and some iron2 the colour is a useful indication of quality1 those presenting a bluish grey appearance being most highly prized1 while those of a yellow colour are somewhat inferior4 ,the stone may be split into various thicknesses1 and prepared for use by grinding either one or both surfaces4 ,they are placed face to face1 and the first grinding is completed with coarse sand1 for the second grinding a finer sand is employed between the two surfaces1 and this is succeeded by a grinding with pumice stone and water1 the stone being finally polished with snake stone4 ,the so-called lithographic chalk1 with which the drawing on stone is sometimes executed1 is composed of finest lamp black 7merely added for colour71 soap1 wax1 tallow1 and shellac2 during the etching1 these ingredients undergo a change1 and form with the stone a chemical compound of great stability4 ,since the fatty acids of the soap and tallow-namely1 oleic and margaric acid--set free by the nitric acid1 combine in the nascent state with the lime to form oleo-margarate of lime4 ,this adheres tenaciously to the stone1 and the whole picture may1 by the application of turpentine1 to all appearances be completely removed from the stone4 ,if the ink roller be again applied1 it will be found that even the finest details remain intact1 and will reappear of their original strength1 the ink only adhering to the oleo-margarate of lime1 and not to the surface of the stone1 which owing to the etching is wet with nitrate of calcium4 ,this is the theory of lithographic etching and printing1 to which it has only to be added that soap and tallow must always be present in the inks or chalks used in drawing to produce the combinations referred to4 ,wax and shellac are only present as binding material4 ,transfer ink1 as used in photo-lithography1 must be slightly thinned1 and this is best done by means of turpentine1 and1 if necessary1 the occasional addition of a few drops of olive oil4 ,should the ink be too stiff1 or be allowed to dry too much upon the transfer paper1 the transfer will probably be faulty1 as the ink will only partially leave the paper4 ,if the ink remains in a soft condition it will be absorbed very readily by the clean dry litho stone 7not etched74 ,owing to the avidity with which all grease is absorbed by the stone1 it is necessary to keep it perfectly free from all such contaminations4 ,to keep the stone in a clean condition while printing it must be etched1 kept damp during working1 and1 on completion or suspension of work1 the surface should be coated with a thick solution of gum arabic4 ,before resuming printing operations1 it is of course necessary to remove the gum from the surface of the stone1 which is done with a damp sponge4 ,as an introduction to the practical work of lithographic transferring and printing the following description of the autographic method will be found of interest1 especially as it bears some similarity to the more difficult process of photo-lithography1 and enables everyone possessing a lithographic press and stones to print their own circulars1 price lists1 c4 ,,chapter ,,xviii4 ,,autography4 ,there are several methods of transferring from specially prepared1 or even any strong well-sized paper4,o ,as the latter may be most convenient1 proceed as follows3 ,write with autographic transfer ink1 readily procurable from dealers in litho requisites2 this will keep for years1 and may be used with any clean steel pen4 ,after the writing has dried1 damp the back of the paper with dilute nitric acid--#a to #c of water4 ,when the writing is visible through the back of the paper1 the sizing has been acted upon sufficiently2 the sheet should be placed in a porcelain dish1 washed in several changes of water1 and blotted off1 leaving it evenly damp without being exactly wet4 ,in the meantime a stone should be adjusted upon the bed of the press1 rubbed over with pumice powder1 and warmed--this may be easily effected by pouring spirits over the stone and igniting it4 ,a suitable scraper--one which1 when pressed against the stone1 allows no light to pass between1 and which should not be wider than the stone--is adjusted in the scraper box4 ,the screw or other appliance for regulating the pressure is then adjusted4 ,the transfer is carefully and accurately placed upon the warm dry stone1 with the writing or drawing face downwards in contact with the polished surface1 a few sheets of waste paper are placed over the whole1 the tympan 7the upper surface of which has been freely rubbed with tallow7 is lowered into position1 the bed is then pushed1 with the stone so covered1 under the scraper box1 so that the scraper may come down1 not upon the extreme edge of the stone1 but about four or five cm4 from the end1 lower the scraper 7or1 according to the construction of the press1 raise the bed7 and pull through under gentle pressure4 ,release the pressure of the scraper1 withdraw the bed1 and raising the corners of the waste sheets used as backing paper1 convince yourself that the transfer is in a proper position and has not moved2 replace the covering paper1 change the position of the stone so that it passes under the scraper in a reversed position1 pass through the press again1 this time with greater pressure4 ,repeat these operations three or four times1 on each occasion under steadily increasing pressure2 remove the transfer carefully by one corner1 and allow the stone to become cold2 sponge over with thick gum solution1 and in this condition it may be left for any length of time4 ,great care must be taken that none of the tallow used on the tympan1 or other grease1 comes in contact with the stone1 either by the hand1 covering paper1 or other means4 ,o ,transfer paper is more reliable4 ,if the transfer should exhibit any signs of weakness while the stone is still covered with plain gum water1 take1 upon a small linen pad1 a little ink thinned either with tallow or a few drops of turpentine2 by careful rubbing in different directions the lines will be considerably strengthened4 ,plenty of gum must be kept upon the surface of the stone during this operation1 at the completion of which it may be removed with a sponge and water1 and the inking-up completed with the roller and the stone gummed in4 ,before printing1 the gum has to be removed by water1 and the stone rolled up with a moderately stiff ink2 it is then etched with gum water rendered slightly acid by a few drops of nitric acid4 ,the best test for the acidity of this solution is to add just so much acid to the gum water that1 after its application to the edge of the stone for two or three seconds1 scarcely perceptible bubbles of carbonic acid gas will show4 ,this is applied evenly to the drawing with a sponge1 and allowed to act for a few seconds4 ,should the ink 8take0 to the stone in places other than the design or writing1 rub the spot at once with woollen material moistened with gum water2 this will clear away the superfluous ink1 but the part should be carefully watched during the printing for any recurrence4 ,after the removal of each impression the stone is damped over the whole surface with a damping cloth before another application of the inking roller4 ,for the production of perfect impressions avoid contact of the hands with the face of the paper or stone1 and care must be exercised that all matters connected with the printing are kept scrupulously clean1 any contamination of a fatty or greasy nature especially being strenuously avoided4 ,the paper used in lithographic printing is usually slightly damped by placing between sheets of damp blotting paper2 such proceeding is not absolutely necessary1 as dry sized paper may also be used4 ,the above detailed description of the necessary sequence of operations in the ,autographic transfer process will assist in understanding that of photo-lithographic transfer1 which requires still more care1 and the use of a special transfer paper so prepared that it is sensitive to light4 ,,the ,,bitumen ,,method4 ,this1 the earliest photographic process1 was discovered and described by ,niepee even before the discovery of photography or silvered plates4 ,it depends on the peculiar property asphalt possesses of losing its solubility in ether1 benzine1 or turpentine after prolonged exposure to light4 ,if it be dissolved in turpentine in a photographically dark room and the solution poured upon a well-polished metal plate or lithographic stone1 dried1 and exposed under a reversed negative 7otherwise the impression yielded in printing will be reversed7 for two or three days,p in sunlight1 the picture may be developed with turpentine or benzine1 either of which solvents will remove the layer from such portions as have been unexposed to the light and reveal a picture in asphalt that may be rolled or inked-in and capable of withstanding etching4 ,this direct process1 as applied to photo-lithography1 is now of little practical value owing to the introduction and perfection of the transfer process4 ,it is1 however1 most valuable in heliographic engraving or etching and for the production of zinc and copper printing plates4 ,p ,the bitumen most suitable is that variously known as ,syrian asphalt1 ,jew's pitch and bitumen of ,judea4 ,this is finely powdered and placed in a bottle with twice the bulk of ether and occasionally agitated for five hours1 at the end of which time the ether may be poured off and fresh supplies added so long as any portion soluble in the ether remains4 ,the purified residuum maybe dried and dissolved in benzole or chloroform2 this will yield a solution which may be used as above1 but poisoning1 perhaps1 twenty times its sensitiveness4 ,the picture is developed with turpentine4 ,,direct ,,photo-,,lithography4 ,this method is little known1 and it may be said that it has never been developed to a practical issue4 ,it is here only incidentally referred to1 but at the same time the fact may be pointed out that these two direct photo-lithographic processes possess a value1 inasmuch as they may be utilised in a comparatively easy manner for the production of grained or half-toned pictures1 presenting less difficulties than by the transfer process4 ,on to a well-cleaned stone1 the surface of which may be either finely grained or polished1 a solution of gum arabic and bichromate is spread1 dried in the dark1 and exposed for a sufficiently long time under a negative2 if the latter be a film it will facilitate the examination from time to time of the progress of the copying4 ,on completion of the exposure the stone should be well washed with water and rolled in with ink4 ,morvan's process is of a similar nature2 a stone is coated with an admixture of albumen #bjj g41 water #cjj g41 bichromate of potassium #ej g41 dried and exposed under a stripped or paper negative4 ,the stone is then first washed with soap1 and afterwards distilled water1 and then rolled up1 gummed1 and the ink allowed to set awhile1 after which printing may be at once commenced4 ,in none of these methods is mention made of etching the stone after inking-in1 as is usual in lithography2 it may be here noted that photo transfers will not withstand so vigorous an etching as drawings executed upon stone in the usual manner4 ,a photo-lithographic transfer may be quite ruined1 even entirely destroyed1 by careless etching2 this is therefore a point of great moment1 and one which has not usually been considered or dealt with in published methods of procedure4 ,we shall have occasion to again refer to it4 ,,photo ,,transfer ,,from ,,paper4 ,in this method1 now universally employed1 success may be said to depend more particularly upon two points4 7#a47 ,the paper for the transfer4 7#b47 ,the suitability of the negative for the purpose in view4 ,the properties and preparation of a suitable transfer paper demand a few words4 ,it should be of substantial body1 smooth and well sized2 that known as bank post is usually employed in this country4 ,professor ,husnik in his patented process proceeds as follows3 #a part of finest gelatine is swelled1 and then dissolved in #bd parts of water a solution of chrome alum #a-ajj in water is added1 and the solution while still warm is poured into a large zinc dish heated to #cd ,r4 by means of a petroleum or spirit lamp4 ,remove any scum from the surface of the solution1 float the paper one sheet at a time1 and suspend to dry4 ,the sheet is floated upon the gelatine solution a second time1 and once more suspended1 this time by the diagonal corner to that by which it was previously hung4 ,prepare a solution of white of egg #a part1 water #b parts1 and on this float the paper on one side4 ,after again drying it is ready for sensitising1 for which operation prepare a bath of water #ad parts1 bichromate of potassium #a part1 methylated spirits #d parts1 adding sufficient ammonia to turn the reddish solution a bright yellow4 ,if the paper is not prepared in large quantities1 but only for immediate use1 the ordinary gelatine paper of commerce,q may be employed with advantage1 if further prepared by floating upon a bath of albumen 7beaten to a froth and allowed to stand7 #ej parts1 water #ej parts1 bichromate of potassium or ammonium #g parts 7,mrkl71 upon which bath the paper should be floated for five minutes4 ,this solution is subject to the disadvantage that even in the dark it will not keep for more than a day or two1 therefore it must be used at once4 ,all photo-lithographic transfer papers1 after sensitising1 should be used within a few hours of their preparation or their good qualities are partially sacrificed1 the solubility of the albumen layer in cold water being impaired4 ,photo-lithographic transfer paper prepared as above described has been for some time in the market1 and may be procured as an article of commerce1 in an unsensitised condition2 it will keep indefinitely in this state1 and may be sensitised as required4 ,the surface should not be allowed to remain in contact with the bath1 neither should the immersion be lengthy1 as in either case the surface of the paper would probably suffer4 ,after drying by suspending by one corner in the dark1 the chromated paper is exposed under a suitable negative--if possible to the sun--for a few minutes only2 it may be examined by non-actinic light1 and when the image appears brown or grey upon a yellow ground1 and all details are visible1 it is removed from the copying frame and entirely covered with a thin coating of transfer ink4 ,this as purchased is much too stiff for use1 and must be reduced by means of turpentine to such a consistency that it is possible to distribute an even and quite thin layer upon the surface of the print1 without its penetrating to the paper4 ,the ink should be so thin that it presents a grey1 not black1 appearance4 ,q ,for instance1 the double transfer paper as used in the carbon process4--,,trans4 ,those who may find it necessary1 or who care to prepare their own ink1 should take--chalk ink 7printing7 #d parts1 beeswax #aj parts1 resin #g parts1 turpentine #dj parts1 tallow #h parts1 ,prussian blue #f parts1 ground and mixed in a paste4 ,the chalk printing ink should be melted by gentle heat1 then add the wax and resin in a molten condition1 then the tallow1 and lastly the ,prussian blue and turpentine2 on account of the inflammable nature of the latter these operations should not be conducted at an open fire4 ,if1 after prolonged keeping1 this ink becomes tough1 and does not readily leave the transfer paper when transferring to stone1 the addition of a few drops of olive oil will restore it to a usable condition4 ,the ink is best applied by means of a fine1 dry sponge1,r with which it should be spread on the transfer as evenly as possible1 during which operation the print must be protected from actinic light2 on its completion the print is placed aside to allow the turpentine to evaporate4 ,this in a warm room will be about ten to fifteen minutes2 the print is then placed in cold water1 care being taken to remove any air-bubbles from its surface4 ,after remaining for about half an hour the uppermost layer will have become sufficiently loose to allow of its removal1 together with the adherent ink not forming part of the picture1 upon the application of slight friction4 ,r ,a smooth composition roller answers equally well4--,,trans4 ,the ,development is readily effected by means of a small1 fine wet sponge1 or a pad of cotton wool well moistened1 which is passed over the print a few times with gentle pressure2 it will be found convenient during these operations to place the transfer face upwards upon a sheet of glass4 ,judgment may be formed at this stage as to the suitability of the negative1 and also as to the correctness or otherwise of the exposure under it of the sensitised paper2 if it should have been too short the finest lines will not be firm1 but appear broken or 8rotten10 as it is technically termed4 ,on the contrary1 should the exposure have been too long1 the spaces between the lines1 which should be quite free from ink1 will retain a certain amount1 in attempting to remove which the transfer will be damaged4 ,washing4--,exposure1 inking1 and development being satisfactory1 the print is thoroughly washed to remove the chrome salt4 ,dry the transfer by means of repeated applications of blotting-paper1 and it is then ready for transferring4 ,transferring4--,the print should retain a little moisture1 but be by no means wet4 ,it should adhere to the warmed stone to prevent any probability of it moving while passing through the press4 ,transfer too ,adhesive4--,should the gelatine surface1 in the judgment of the operator1 appear likely to prove too adhesive1 it may be further dried before use1 or placed for two minutes in a one per cent4 solution of tannin1 and again dried between blotting-paper4 ,preparation of ,gelatine ,transfer ,paper1 as used in the ,imperial ,military ,geographical ,institute in ,vienna1 is described as follows in the 8,photographic ,correspondence03--,a sheet of well-sized paper is soaked in a dish of water1 and when thoroughly limp is allowed to drain1 and then placed on a horizontal glass plate4 ,all air bubbles and superfluous moisture are removed by blotting-paper and a squeegee1 the edges of the paper are turned up to the depth of about #b cm41 and a warm gelatine solution 7#a to #cj7 poured upon the paper4 ,it sets in a few minutes1 and the sheets are placed upon wire gauze to dry1 this operation usually occupying about two days4 ,a day before using the gelatine paper is sensitised by immersing for three minutes in a cold bath of bichromate of potassium 7#a to #ae74 ,on removal from the bath it is allowed to drain1 and the gelatine side placed upon a glass plate4 ,the back is dried with blotting-paper1 and all air bubbles removed4 ,these operations and the subsequent drying must be performed in a non-actinic light4 ,it may occur that after these operations the sheets when dry adhere partially or wholly to the glass plate4 ,to prevent such an occurrence it is well to wax the plate1 as in the carbon process1 or to apply to the surface a weak solution of ox-gall4,s ,when dry the sheets are cut to the required size and printed under the negative4 ,on removal from the printing frame they are placed in cold water until quite limp1 removed1 placed face upwards upon a glass plate1 and surface dried with blotting-paper4 ,should the gelatine swell too much the sheet is placed for two minutes in a chrome-alum solution 7#a to #bjj7 and again blotted4 ,ordinary transfer ink1 thinned with turpentine1 is now thoroughly rolled up on the inking slab by means of a leather roller 7as previously described in the instructions under ,collotype72 a fine velvet roller1 lightly charged with ink1 is then passed over the still moist transfer4 ,should the latter become dry in places it is again passed through the water bath1 and the inking is again proceeded with4 ,if the ink adhere to other parts than the design it is easily removed by the application of a damp sponge or the tip of the finger4 ,the process of transferring to stone is as previously described4 ,the stone itself is prepared in the manner described for the autographic process 7see page #ace74 ,damp the back of the transfer with water only1 and after passing through the press several times1 remove the paper from the stone2 if of good quality this may be done without tearing4 ,the transferred impression being still easily obliterated1 it is better to let the stone stand for a few hours without gumming2 this will allow the ink to dry deeper into it4 ,coat the whole of the surface with a moderately thick solution of gum1 and again allow to dry4 ,in this condition it may remain indefinitely1 but under any circumstances it is advisable to allow it to remain a day before etching and printing4 ,the gum solution used should be freshly prepared1 as when old it becomes acid and acts as a mild etching medium4 ,remove the gum with a clean sponge previously to printing1 and while the stone is evenly damp with gum solution the picture may be either rolled up with stiff chalk ink1 applied by means of a leather roller1 or1 as preferred by many1 rubbed in with a sponge containing thinned transfer ink4 ,when the drawing appears clean and perfect the stone is washed with a wet sponge1 coated with gum1 placed aside to dry1 and allowed to stand for a day4 ,after the removal of the gum proceed as previously described1 viz41 roll up with stiffish ink1 nowhere allowing the stone to become dry1 and etch4 ,this operation must be conducted with care and judgment1 or there will be a probability of losing the finer lines of the drawing4 ,the best mordant to use is nitric acid1 so dilute as to taste no stronger than lemon juice1 and which1 placed upon the edge of the stone for a few seconds1 will show only slight effervescence4 ,to this is added a little gum-water1 and it is then evenly and quickly spread over the stone4 ,after being allowed to act a few seconds1 the stone is sponged over with clean water1 and is then ready for printing from4,t ,there are many practical lithographers who prefer to entirely remove the visible image from the stone by means of turpentine before printing4 ,a little gum is left upon the stone1 and while the latter is still moist the drawing is removed by means of turpentine upon a piece of rag2 the latter must not be too frequently changed1 or a too liberal supply of turpentine made use of1 or the drawing may be irreparably damaged4 ,unless the latter be the case the picture will reappear upon applying the roller charged with chalk ink4 ,as may be expected1 the first few impressions are seldom so perfect as the later productions4 ,after each impression is removed the stone is at once slightly moistened4 ,for this purpose a soft1 clean sponge is suitable1 or damping cloth1 as supplied by dealers in printing materials4 ,the sponge or cloth should be thoroughly wetted1 wrung as dry as possible1 and in that condition will possess the necessary dampness4 ,in rolling it should be borne in mind that as in ,collotype a stronger grip of the roller handles and heavy pressure with slow rolling will deposit ink upon the drawing--while1 on the other hand1 light quick rolling of the drawing will tend to remove the ink4 ,to leave the stone without gumming after transferring is a convenient method of rendering the transfer more receptive of the ink4 ,in lithographic as compared with ,collotype printing the ink is reduced to a far greater extent with varnish1 while both the inking slab and roller are charged far more heavily4 ,the paper may be damp1 or a dry1 well-sized paper may be used4 ,s ,a more reliable method of imparting to the surface of the paper a high gloss is to squeegee it down upon a ferrotype plate1 the surface of which requires no preparation1 and the risk of sticking is nil4--,,trans4 ,t ,for etching extremely delicate transfers a decoction of ,aleppo gall with gum is to be recommended4 #ae gr4 of crushed nut galls are boiled for one hour in half a kilo of water and strained through a cloth4 ,to etch the transfer add a few drops of this solution to a solution of gum of a syrupy consistency2 spread over the stone with a soft sponge1 and allow to dry4 ,,chapter ,,xix4 ,,negatives ,,for ,,photo-,,lithography4 ,an unconditionally good negative is required for photo-lithography1 and those who have not seen one produced for the purpose by an expert should endeavour as a first step to do so1 or they will scarcely be likely to devote the attention necessary for producing one of a thoroughly suitable character4 ,not only must the lines of the copy be represented in the negative by clear glass1 and the white ground of the original be represented by opacity1 but the utmost sharpness of definition of the finest dots and lines to the very corners of the plate is absolutely necessary to render the negative thoroughly serviceable4 ,to produce such a negative a lens entirely free from distortion1 and capable of giving microscopic definition1 is1 of course1 a first necessity4,u ,u ,lenses of the rectilinear or symmetrical class are best4 ,the ,wet ,collodion ,process is better adapted than any other for the production of suitable negatives1 possessing the necessary density and freedom from fog or veil4 ,the bath must work with the utmost cleanliness1 and the collodion should not be used too soon after iodising4 ,the developer works better when not quite fresh1 and should contain a sufficiency of acid1 and the negative1 after fixing1 should be subjected to a vigorous intensification4 ,professor ,husnik thus comments upon negatives for photo-lithography3-- 8,as in photo-lithography only subjects in black and white line or stipple can be reproduced1 to the entire exclusion of half-tone1 the negatives should represent the copy by clear lines and opaque spaces4 ,this is seldom the case except in instances where the drawings are specially prepared1 and the subjects somewhat bold and coarse4 ,for example1 in copying a proof from a fine steel engraving the graduated1 grey1 hair-lines1 appear in the negative somewhat veiled1 whereas the intermediate spaces between close shading1 and which are somewhat toned in the print1 are not developed actually opaque in the negative4 ,on this account the fine hair-lines will take longer to print in the copying-frame than the bolder shadow lines4 ,the latter may develop faultlessly1 while the ink may leave the hair-lines4 ,the intermediate spaces between close shading may not be sufficiently opaque in the negative1 consequently the print is over-exposed in these portions1 and during development remains covered with ink4 ,such faults must be overcome as far as possible by shading the negative during printing in the usual well-known manner40 ,the ,colour and condition of the original copy will greatly influence the class of negative it is possible to obtain1 and if allowable it will be advisable ,to ,bleach old engravings or other copies1 either yellow from age or stained1 by immersing them in eau-de-javelle,v #aj cc41 water #ajj cc41 wash in water for two hours1 and finally in a weak solution of hyposulphite of soda4 ,v ,chloride of lime #a oz4 ,water #ae oz4 ,carbonate of potash #b 0 ,water #e 0 ,mix the two solutions together1 boil1 and filter before use4 ,intensifying4--,having developed a clear1 sharp negative1 wanting only in density1 it must be intensified to the utmost limit--without fogging--first with citric acid1 pyrogallic acid1 and silver4 ,this solution may be applied either before or after fixing1 preferably the former2 if this course is adopted1 after washing and fixing1 and again thoroughly washing1 the final intensifying operations may be proceeded with4 ,opinions vary as to the actual best method to adopt1 but preference is usually given to an intensification by a salt of mercury or lead2 under any circumstances there must be a good deposit of silver to work upon1 or the necessary density cannot be obtained4 ,in fact1 a negative too thin1 submitted to mercurial combinations1 particularly the bichloride1 will become more bleached and spotty1 and the after application of sulphide of potassium will not again restore it2 the deposit will assume a dark brown appearance1 but the spots arising from the mercurial salts will still be apparent4 ,the two mercurial salts referred to are--7#a7 ,bichloride of mercury1 corrosive sublimate1 a well-known and highly-poisonous substance used in solution in water1 and 7#b7 iodide of mercury1 which1 used in intensification1 acts more evenly1 though with somewhat less energy4 ,this substance1 which is of a beautiful red colour1 is insoluble in water1 but is soluble in sublimate1 and also in a solution of iodide of potassium4 ,it is recommended for intensification1 and is easily obtained by dropping into a solution of bichloride of mercury--with agitation--a concentrated solution of iodide of potassium until the red precipitate as first formed is again dissolved4 ,this yellow solution may be diluted as required by an addition of ten times its volume of water4 ,if1 instead of flowing the solution over the negative1 a dipping bath be used1 into which the negative is steadily lowered for a few seconds1 a more uniform intensification is likely to ensue4 ,carefully watch the plate1 and stop the action before it goes too far1 or the silver deposit will lose strength in parts4 ,an important gain in density may be obtained by exposing to sun or daylight a negative which has been developed and intensified with pyrogallic acid1 fixation taking place after drying4 ,the negative must be thoroughly washed before exposure to light1 and with ordinary care there is little danger of fogging4 ,illumination of the ,copy should be perfectly even1 a front light being made use of1 and direct sunlight if possible4 ,the latter is seldom admitted direct into the studio1 and against outside work wind and rain are almost fatal objections4 ,where much copying has to be done it will be found an advantage1 if at certain hours of the day the sun shines direct upon the studio1 to remove all blinds1 screens1 or other obstructions1 and so allow the rays to fall direct upon the print or drawing to be copied4 ,a ,side ,light1 particularly if direct sunlight1 must be avoided1 as any unevenness or grain of the paper will be exaggerated and rendered more apparent if lighted in such a manner4 ,under ,exposure1 if slight1 is a fault much to be preferred to an error in the opposite direction4 ,new ,transfer ,paper for ,photo-lithography4--,in the photographic office1 ,calcutta1 a new method of preparing the photo-lithographic transfer paper with arrowroot has quite recently been introduced1 which1 as is said1 has the advantage of being much cheaper than the method of coating with gelatine usually adopted1 and of giving results quite as good1 if not even better1 than by the old proofs4 ,bank post paper is coated in the usual way with two coats of the following mixture3-- ,arrowroot #adj parts ,bichromate of potash #gj 0 ,water #c1ejj 0 ,after exposure to light1 the prints are coated with transfer ink in the press as usual1 the transfer ink used being composed of-- ,hard re-transfer ink 7plate to stone7 #ajj parts ,lithographic chalk ink #ajj 0 ,palm oil #g 0 ,after inking in the prints are washed off with hot water1 hotter than is required for gelatine transfers4 ,the arrowroot transfer prints are found to go down well on the zinc without sticking1 and give clear1 sharp transfers4 ,gelatine ,plates have hitherto been considered almost useless for photo-lithography4 ,messrs4 ,mawson and ,swan1 however1 have recently introduced a special make1 known as the 8,photo-mechanical0 plate1 which gives negatives of great density1 and at the same time clearness in the shadows4 ,the makers recommend the ammonia-pyro developer1 with meta-bisulphite of potash4 ,it will be found of considerable advantage if1 before proceeding with the development1 the plate be submitted for one minute to a bath of water #b ounces1 gallic acid #f grains2 this1 without prolonging the development1 will add considerably to the density of the resulting negative4 ,,chapter ,,xx4 ,,application ,,of ,,the ,,carbon ,,process ,,to ,,photo-,,lithography4 ,an ,ingenious ,process1 capable of yielding satisfactory results1 is one in which a carbon print is transferred to and developed upon the stone direct4 ,such operation will present no difficulty to those familiar with the details of the process4 ,in the 8,photographic ,archives10 vol4 #ag1 page #aic1 are to be found working details1 and it is there shown that by this method it is possible to directly transfer to stone pen and ink sketches1 impressions from woodcuts1 or copper-plates1 without the necessity of a photographic negative4 ,this process may1 therefore1 be available in cases where anastatic,w printing is not applicable4 ,w ,the anastatic process consists in reproducing by zincography a copy of any recently printed matter4 ,the subject for reproduction is moistened on the back with dilute nitric acid4 ,it is then laid face downwards upon a freshly polished sheet of zinc and passed through the press4 ,printing is then proceeded with as in zincography4 ,a lithographic stone may also be used1 if1 before laying down the impression1 the face is moistened with turpentine1 and allowed nearly to dry4 ,to those unacquainted with carbon printing it may be pointed out that it is a most valuable process1 affording great facilities for the reproduction and reversal of negatives for ,collotype4 ,a knowledge of the process is here presumed1 as it would necessitate too wide a digression to give an ample idea of the many useful applications of this beautiful and permanent method of printing4 ,very complete instructions will be found in ,dr4 ,leisegang's 8,carbon ,process40,x ,as regards the application of this process to lithography1 only pictures devoid of half-tone1 such as drawings in line and dot or impressions from engravings1 are suitable for reproduction by this method1 if upon clean paper 7not too thick7 and printed on one side only4 ,the sensitised tissue may be printed from the original by contact1 in the printing frame1 instead of producing a negative in the camera by contact upon a dry plate4 ,should it be decided to print direct from the copy surround the edges of the same with strips of black paper or tinfoil1 half-an-inch wide1 and in a weakly actinic light4 ,so adjust the ordinary sensitised carbon tissue that its edges are about in the centre of the surrounding strips1 care being taken that the edges of the tissue nowhere extend beyond them4 ,x ,translated by ,r4 ,b4 ,marston1 and published by ,sampson1 ,low and ,co41 ,fleet ,street1 ,e4,c4 ,the 8,a ,b ,c of ,pigment ,printing10 published by the ,autotype ,co41 ,oxford ,street1 ,w4,c41 may also be recommended4 ,expose to ,daylight for a time1 gauging the exposure by means of the actinometer4 ,probably it will be necessary to print till the #g shows4 ,a ,finely-polished ,stone is dusted and adjusted in a horizontal position1 and flowed over with cold water4 ,the ,exposed ,tissue is placed in cold water1 and allowed to soak till quite limp4 ,it is then placed face downwards upon the wet stone1 covered with indiarubber sheeting1 and squeegeed into close contact with the stone2 allow to remain under pressure for half-an-hour to an hour4 ,development is effected by pouring warm water about #ajj ,f4 over the back of the exposed tissue4 ,so soon as the colour exudes around the edges of the paper backing1 the latter may be removed1 and the development proceeded with by continuing to pour warm water over the surface4 ,only a slight impression should remain--the lines showing the bare stone perfectly clear and clean4 ,allow the stone to dry in a cool1 shady place without the application of artificial heat4 ,roll ,up with lithographic chalk ink until the surface presents a solid black appearance1 stand the stone aside for a few hours to allow the ink to penetrate its surface1 and then ,remove the ,negative carbon print from the stone by means of a piece of woollen cloth moistened with a thin solution of gum4 ,this takes some time1 but it will be found that the fatty ink has penetrated where unprotected by the carbon negative1 and has formed a complete positive4 ,gum ,in1 etch1 and proceed as in ordinary lithographic operations4 ,it cannot be expected that the operation1 as conducted above1 will produce the finest results2 the drawing will usually require a certain amount of retouching at the hands of the lithographic artist1 who will1 however1 often be saved a vast amount of trouble4 ,it is obvious that if the proceedings1 as described1 be carried out1 using1 however1 a photographic glass positive in place of the printed impression1 the process will be found capable of giving much finer results1 and the exposure will be very materially decreased4 ,,transposing--,,black ,,and ,,white4 ,a modification of the foregoing process may be utilised for the reversal or transposition of black to white1 or vice versa1 of any subject of which a print may be obtained in printing ink4 ,an ,impression is first obtained either upon sensitised carbon tissue or1 preferably1 on a thinner paper1 coated and sensitised as for photo-lithography4 ,such paper must not be submitted to a light of much actinic power during or before printing1 and as much ink as possible should be used without risk of filling up the work4 ,dust ,over the impression while still wet any dense opaque colour1 applied by means of wool or camel-hair brush1 carefully going over every part and piling on as much colour as possible1 after which ,expose the ,paper bearing the print so treated to the light for a short period1 dependent upon the light and sensitiveness of the paper4 ,if it be a full impression1 well dusted1 the latitude in exposure will be very considerable4 ,ink ,up the whole surface of the paper with lithographic transfer ink1 thinned with turpentine1 and applied by means of a sponge or roller4 ,develop1 as in photo-lithography1 either by means of warm or cold water1 according to the coating upon the transfer-paper4 ,the sensitised paper1 where protected by the ink impression1 has not been hardened by the action of the light1 and readily parts with the ink and colouring matter4 ,if the impression has been one from ordinary type it will now show in the form of white letters on a black ground4 ,transfer to ,stone1 and otherwise treat as an ordinary photo-lithographic transfer4 ,,engraved ,,negatives ,,for ,,photo-,,lithography4 ,in certain processes for the production of photo-relief blocks many operators prefer artificial negatives1 in the production of which photography has played no part1 but which are1 on the contrary1 the direct production of the artist's hand4 ,factitious ,negatives may be produced by coating a plate with a transparent but non-actinic coating1 and by removing or erasing in a suitable manner designs may be copied without the use of a camera or lens4 ,professor ,husnik and others have published different methods whereby the artist is enabled to transfer the creations of his pencil to zinc or stone1 without resorting to the aid of the photographic negative process1 although the subsequent operations may still entitle it to be styled photo-lithography4 ,the process most likely to lead to success consists of first coating a glass plate with a strongly iodised collodion1 sensitising as usual1 well washing on both sides and drying4 ,to engrave1 lay the plate upon a black cloth1 and the design may be traced and engraved upon the surface by means of etching points or needles4 ,remove all loose particles of collodion from the plate by gentle brushing when the drawing is completed4 ,immerse the plate a second time in the silver bath1 and develop with either pyrogallic acid or sulphate of iron developer4 ,husnik proposes to first coat the plate with a solution of pure fuchsin1 and afterwards with one of gum1 and then engrave as previously indicated4,y ,y ,major ,waterhouse has published the following ingenious method of transforming a drawing on paper into a photographic negative3--8,a tracing1 or drawing1 is made in lithographic ink on tracing paper1 using plenty of ink on the lines4 ,the drawing is then placed on a board over a piece of blotting-paper1 and brushed all over with a strong solution of aniline brown in water2 when dry it is rubbed over with a tuft of cotton wool soaked in turpentine1 which removes the ink without altering the coloured ground4 ,the lines then appear clear on a dark reddish brown ground4 ,the negatives thus obtained are good1 but more suited for coarse than fine work40 ,it may be suggested1 why not transfer the drawing direct to stone1 and produce the necessary copies by lithography8--,,trans4 ,by either of these methods negatives of extreme density and absolute clearness in the lines may be produced and used for obtaining impressions in ink1 the transfer of which to stone presents no difficulty4 ,it remains to be added that there are several methods of producing grained negatives for photo-lithography in half-tone1 and therefrom a transfer for stone1 and so obtaining impressions at a much greater rate than is possible from a ,collotype plate4 ,they may each produce results with a certain amount of success2 but even those from the best methods indicated cannot be compared with ,collotype4 ,the too obtrusive grain of the half-tone pictures so produced destroys much of the finer details1 and it is to be regretted that all such processes leave so much to be desired4 ,,appendix4 ,,the ,,steam ,,collotype ,,machine4 ,the earliest steam machines for ,collotype printing were made by ,faber ,co41 of ,offenbach2 they were1 however1 so complicated and delicate in construction that other machines have entirely supplanted them4 ,the three principal varieties are those of ,alauzet ,co41 of ,paris2 ,koch1 of ,leipzig2 and ,schmiers1 ,werner ,stein1 each of which may be considered entirely successful2 they possess features of great similarity1 differing not in principle1 but only in details of construction4 ,contrasting the work of the machine with that of the press1 the printing is much more rapid1 and the prints more uniform and regular1 while the 8life0 of the plate is greatly lengthened2 one capable of yielding #bej impressions on the scraper press would1 in all probability1 give #a1jjj on the machine--a fact easily accounted for when it is considered that the one is produced by a scraping pressure while the other is made by the rotation of a cylinder4 ,as will be seen by the illustrations1 the machines bear a considerable resemblance to those used in lithography--they may1 in fact1 be used for lithographic printing--with very greatly increased inking power4 ,the machines are so constructed that the plate may be inked once1 twice1 or three times1 each inking giving more vigour1 but1 of course1 a corresponding decrease in the number of impressions yielded2 the output may be relatively estimated at #a1ejj1 #a1jjj1 and #hjj per day4 ,it is1 of course1 an impossibility to teach machine printing by means of instructions such as may be conveyed in a work like the present1 and the following remarks are added more with a view of giving a general idea of the nature of the necessary operations than with any idea of making the reader a competent machine minder4 ,the ,preparation of the ,plate for the machine is identical with its preparation for the hand-press1 but greater uniformity1 both in the negative1 exposure1 and etching1 are demanded than by the hand-press4 ,for the latter considerable latitude is permissible1 as the intelligent printer may1 by varying his rollers1 his rate of rolling and other little dodges1 produce perfect impressions from plates which would1 under the entirely mechanical action of the machine1 fail lamentably4 ,adjustment of the ,rollers is so effected that they are lifted about #b mm4 when passing over the inking slabs and the printing plate2 if a greater lift is necessary to bring them upon the printing surface marks will be produced upon the plate1 and if arranged for a less lift they will probably skid over the plate1 damaging the printing surface4 ,they should also be adjusted perfectly parallel with the surface of the inking tables1 or one side only may come in contact with the work4 ,fixing the ,plate to the bed of the machine is effected in several ways1 but usually with small clips1 as described for the hand-press4 ,all adhering gelatine1 etc41 must be removed from the plate1 and a thin sheet of white paper inserted between it and the bed of the press4 ,the faces of the metal clips must be protected with strips of leather1 cork1 or some such elastic bodies1 otherwise the pressure exerted would cause the glass to fly4 ,a straight edge is placed across the machine1 and the bed lowered by means of inclined planes attached to suitable gearing until the surface of the plate is well below the circumference of the cylinder1 and from this position it is brought up to its proper level1 raising each side equally1 that the pressure may be perfectly uniform4 ,packing the ,cylinder4--,the cylinders are so constructed that the iron surface does not come in actual contact with the printing paper4 ,in fact1 there is a deficiency between the actual and necessary diameter of the cylinder of a few mm41 sometimes as much as #g mm4 ,this is compensated for by the addition to its surface of 8packing10 which gives a more elastic pressure than the unyielding surface of iron4 ,this packing is not applied to the entire surface of the cylinder1 but is so devised that it exerts pressure upon the surface of the picture only4 ,a sheet of smooth four-ply cardboard is attached to the cylinder by means of thin glue1 this first sheet usually exceeding the size of the picture4 ,to this is attached a second piece1 cut of the exact size of the image1 and attached by means of the glue1 forming a raised block in exact register with the position of the picture on the printing plate2 this is covered with a thickness or two of fine blotting-paper1 and over the whole the sheeting of the cylinder is tightly stretched in the usual well-known manner4 ,it is self-evident that the circumference of the cylinder must traverse at exactly the same speed as the bed of the machine1 or there will be a horizontal rubbing or friction between the surface of the printing paper and that of the printing layer1 which will result in impressions lacking in sharpness1 and ultimate destruction of the plate4 ,masking the ,prints for the production of white margins is usually performed by one of two methods1 each having advantages and disadvantages which should be carefully considered before adopting either2 both are in practical use4 ,in one is used a light rectangular iron framework or 8frisket10 conforming to the size of the cylinder1 to which it is attached by hinges4 ,this framework is opened and closed automatically1 remaining open during the period the cylinder is resting and the inking is taking place4 ,at this point the 8layer-on0 inserts the paper1 it is seized by the grippers1 and the masking frame closes down into suitable grooves in the circumference of the cylinder1 such grooves being useful to prevent any lateral movement of the frame4 ,to the latter are attached four movable strips of thin zinc1 which may be adjusted by means of set screws to form an opening of any desired size4 ,the printing paper being inserted in the grippers1 the frame closes1 holding the paper upon the cylinder1 the strips of zinc at the same time protecting the edges of the paper from immediate contact with the printing layer1 the cylinder revolves1 and the printing is effected4 ,in large sizes the zinc strips are necessarily of such strength that the edges would cut and damage the printing layer2 it is therefore usual to adjust the strips to within about #e mm4 of the edges of the picture1 and by attaching strips of varnished tissue paper to the zinc1 reducing the aperture to the size of the picture in hand4 ,in large sizes--where thin paper is used1 or where narrow margins are desired--this system of masking is best1 as the whole of the operation is entirely automatic4 ,the layer-on may devote the whole of his attention to removing impressions and inserting fresh paper4 ,another ,system of masking frequently made use of is one in which an aperture of suitable size is cut in a piece of cardboard1 such aperture being1 say1 #b mm4 larger than the print4 ,the portion removed is reduced in size by #b mm4 all round1 leaving it exactly the size of the impression desired4 ,this piece is utilised for packing by attaching to the cylinder as previously described4 ,the cardboard mask1 presenting the exact appearance of a sunk mount1 is affixed by means of a bar to the cylinder1 and when folded down upon the latter1 the 8cut out0 used as packing exactly occupies the centre of the mask1 leaving a marginal space all round of #b mm4 ,before printing1 the mask must be varnished with negative varnish1 bitumen in benzol1 or otherwise waterproofed1 to prevent adhesion to the print layer4 ,the mask has to be turned back by hand at the insertion of each sheet--a considerable disadvantage when compared with the automatic frame4 ,on the other hand1 its advantages are simplicity of preparation1 and the possibility it allows of masking and printing several irregularly-disposed pictures on one sheet4 ,damping the ,plate4--,the use of the cylinder pressure has further advantages than merely prolonging the life of the plate--the operation of damping is much less needed than on the hand-press4 ,the printing paper does not come in contact with the plate before the instant of printing or remain upon it after the operation1 but is held to the cylinder by the grippers and mask1 and so carried over the inked plate1 consequently little opportunity is afforded for absorption of the etching fluid4 ,with chalk paper and a new plate damping may be necessary every twenty-five impressions1 but as the plate becomes older fifty or even one hundred may be printed between the etchings4 ,on plain paper of hard surface much longer numbers may be expected4 ,the ,inking ,tables1 two in number1 are provided one at either end of the machine1 necessitating two sets of inking rollers--one of leather for applying the thick ink1 and another of composition for supplying the 8half-tone10 the latter set requiring such light application to the plate that no riders are required4 ,there are also the usual distributing rollers1 to which the ink is generally supplied by the printer as may be necessary1 the quantity being so small that no actually satisfactory automatic duct has yet been devised4 ,a proper adjustment of the consistency of the two inks to the requirements of the plate in hand is a matter of considerable delicacy1 for should the ink supplied to the leather rollers be too thin it is immediately removed from the printing plate by the composition rollers2 these again transfer it to the table devoted to the thin ink1 and a general 8wash up0 is the necessary result4 ,the ink first supplied to the leather rollers should be as stiff as possible1 afterwards reducing as experience may dictate1 while to the composition or tone rollers merely coloured varnish1 or even varnish alone1 is applied1 as the latter often remove enough colour from the printing plate to sufficiently tint the varnish applied to their surface4 ,the leather rollers should be cleaned daily by scraping1 and the composition set washed1 unless the weather be very cold or damp4 ,in such cases they may be allowed to stand under ink1 as they will in that condition be less susceptible to atmospheric changes4 ,double ,printing is sometimes resorted to for work of a high class1 and when negatives too thin to produce good results otherwise are unavoidably used1 such work is usually printed on chalk paper and without masking4 ,the printing plate is usually inked up twice and an impression taken2 without removing the impression from the cylinder the plate is again twice inked and a second impression pulled on the same piece of paper1 the two images being exactly super-imposed4 ,the great gain in contrast will be understood when it is considered that while the high lights of the picture gain absolutely nothing1 the strength of the shadows is exactly doubled4 ,the results produced in this way are simply astonishing when contrasted with silver prints from the same negatives4 ,,advertisements4 ,,hugo ,,koch1 ,,leipzig-,,connewitz1 ,,germany1 ,,manufacturer ,,of ,,collotype ,,steam ,,presses4 ,awarded ,first ,prizes at all ,exhibitions where our ,presses have competed4 -- ,world's ,exhibition1 ,antwerp1 #ahhe1 ,diploma of ,honour4 -- ,illustration ,,the ,,koch ,,collotype ,,steam ,,press ,,is ,,the ,,best ,,in ,,the ,,market ,,made ,,in ,,four ,,sizes4 ,,automatic ,,feed ,,board1 ,,frisket1 ,,and ,,ink ,,duct4 ,if desired1 the press can be arranged also for litho or type printing 99499 ,that these machines have been adopted1 to the exclusion of all others1 in establishments of such repute as those of ,albert1 of ,munich1 and the 8,phototypisches ,institute0 of ,berlin1 are facts of the greatest significance4 ,,prices ,,and ,,particulars ,,on ,,application ,,to ,,hugo ,,koch1 ,leipzig-,connewitz1 ,,germany1 ,,or ,,beesley ,,co41 ,,york ,,passage1 ,,birmingham4 ,,schmiers1 ,,werner ,,and ,,stein1 ,,manufacturers ,,of ,,printing ,,machinery ,illustration ,,our ,,collotype ,,machines have now been introduced for upwards of twelve years1 during which period they have been adopted by the most renowned ,collotype establishments in all countries4 ,they are manufactured in four sizes1 with all recent improvements1 and may be ordered either with or without masking frames1 the utmost satisfaction being guaranteed4 ,they may be utilised for ,lithographic ,printing4 ,litho ,steam ,machines in ,five sizes4 ,bronzing ,machines in ,two sizes4 ,further information in reply to all questions on application to ,,schmiers1 ,,werner ,,stein1 ,d,,sener ,,weg1 ,,leipzig4 ,,established #ahbc4 ,,berger ,,wirth1 ,,leipzig1 ,,germany1 ,ink ,manufacturers4 ,,specialities-- ,,collotype ,,inks ,in all ,shades4 ,,prices ,,and ,,samples ,,forwarded ,,upon ,,application4 ,illustration ,,the ,,mawson 8,photo-,mechanical0 ,plates ,,are ,,specially ,,made ,,for ,,photo-,,lithographers1 ,,photo-,,etchers ,,copying4 99 99 99 99 99 ,collodions1 ,varnishes1 ,chemicals1 and other requisites for ,photo-,engravers1 etc4 99 99 99 99 99 ,,mawson ,,swan1 #cc1 ,,soho ,,square1 ,,london1 ,w41 ,,and #ae1 ,mosley ,street1 ,,newcastle-,,on-,,tyne4 ,,gelatine4 ,,nelson',s ,,photographic ,,gelatine ,,is ,,recognised ,,as ,,the ,,best for all ,photographic purposes4 ,no4 #a4--;,,for ,,dry ,,plates4 ,no4 #b4--;,,for ,,carbon ,,process4 ,nelson's 8,special ,x ,opaque10 for ,dry ,plates4 ,sold ,retail by all ,dealers in ,photographic ,materials4 ,wholesale by the ,manufacturers-- ,,geo4 ,,nelson1 ,,dale and ,,co41 ,,limited1 #ad1 ,,dowgate ,,hill1 ,,london1 ,e4,c4 ,,eastman',s ,,stripping ,,films ,illustration ,produce the most perfect ,reversed ,negatives for ,collotype and ,photo-,lithography1 and1 when used in ,,eastman',s ,,roller ,,slides1 reduce the bulk and weight immensely4 ,,eastman',s ,,permanent ,,bromide ,,paper4 ,,eastman',s ,,transferotype ,,paper4 ,the ,eastman ,dry ,plate ,film ,co41 #aae1 ,,oxford ,,street1 ,,london1 ,w4 ,,an ,,introduction ,,to ,,the ,,science ,,and ,,practice ,,of ,,photography3 ,,by ,,chapman ,,jones1 ,f4,i4,c41 ,f4,c4,s41 ,,demonstrator ,,of ,,practical ,,chemistry ,,in ,,the ,,normal ,,school ,,of ,,science ,,and ,,royal ,,school ,,of ,,mines2 ,,member ,,of ,,the ,,photographic ,,society ,,of ,,great ,,britain1 ,c4 ,cloth1 price #c_/f2 post free1 #c_/aj-a_/b4 ,paper ,covers1 #b_/f2 post free1 #b_/aj-a_/b2 ,,iliffe ,,son1 #c1 ,st4 ,bride ,st41 ,ludgate ,circus1 ,london1 ,e4,c4 ,,the ,,best ,,first ,,book ,,for ,,photographers ,,to ,,be ,,had4 ,,photography ,,for ,,all3 ,an ,elementary ,text ,book and ,introduction to the ,art of ,taking ,photographs2 ,,by ,w4 ,,jerome ,,harrison1 ,f4,g4,s41 ,,author ,,of 8,a ,,history ,,of ,,photography10 ,,and ,,european ,,editor ,,of 8,,the ,,international ,,annual ,,of ,,anthony',s ,,photographic ,,bulletin40 ,,price ,,one ,,shilling4 ,post free1 #ad ,stamps4 ,,london3 ,,iliffe ,,son1 #c1 ,st4 ,bride ,st41 ,ludgate ,circus4 ,,all ,,articles ,,for ,,collotype1 ,,photo-,,lithography1 ,,and ,,etching ,,processes1 ,,as ,,presses1 ,,papers1 ,,inks1 ,,rollers1 ,,chemicals1 c4 ,,may ,,be ,,obtained ,,through ,,romain ,,talbot1 ,,br,,derstrasse #aj1 ,,berlin ,c4 ,,special ,,general ,,price ,,list ,,gratis ,,on ,,demand4 ,e4 ,t4 ,,gleitsmann 7,established #ahea47 ,,dresden1 7,established #ahea47 ,,ink ,,manufacturer4 ,,speciality-- ,,black ,,coloured ,,collotype ,,inks ,,and ,composition for ,collotype ,rollers4 ,f4 ,,drescher ,,co41 ,,gelatine ,,works1 ,,oberndorf1 ,schweinfurt a_/ ,main1 ,,germany1 ,,manufacturers ,,of ,,improved ,,gelatine ,,for ,,emulsion4 ,,improved ,,gelatine ,,for ,,collotype4 ,special ,gelatines for all ,photographic purposes4 ,,the ,,indispensable ,,handbook ,,to ,the ,optical ,lantern3 ,a ,,complete ,,cyclop,,dia ,,on ,,the ,,subject ,,of ,,optical ,,lanterns1 ,,slides1 ,,and ,,accessory ,,apparatus4 ,,compiled ,,by ,,edited ,,by ,,walter ,d4 ,,welford4 ,,henry ,,sturmey4 ,,contents4 ,,section ,i4 ,,part #a4--,the ,cheaper ,oil ,lanterns4 ,better ,class ,oil ,lanterns4 ,double or ,dissolving ,oil ,lanterns4 ,,part #b4--,single ,limelight ,lanterns4 ,biunials4 ,triunials4 ,special ,lanterns4 ,,part #c4--,scientific ,lanterns4 ,,section ,,ii4 ,,part #a4--;,,illuminants--,lamps1 ,jets1 and ,accessories4 ,,part #b4--,lenses1 ,condensers1 c4 ,,part #c4--;,gas1 ,apparatus1 ,retorts1 ,purifiers1 c4 ,bags1 ,cylinders1 ,valves1 ,pressure ,boards1 c4 ,,part #d4--;,exhibition4 ,screens4 ,screen ,frames4 ,reading ,lamps4 ,desks4 ,tripods4 ,boxes4 ,tables1 c4 ,,part #e4--;,accessories4 ,microscope4 ,polariscope4 ,aphengescope1 c4 ,,section ,,iii4 ,,part #a4--;,carriers4 ,frames4 ,tinters1 ,registering ,apparatus1 ,grooved ,boxes1 c4 ,,part #b4--,,slide ,,makers ,,and ,,slide ,,painters--,notices of their ,productions and ,specialities4 ,,part #c4--,,slides--,temperance1 ,tales1 ,scriptural1 ,scenery1 ,nursery ,tales1 ,historical1 ,entertainments1 ,pantomimes1 ,educational1 ,comic1 ,movable1 ,effect and ,dissolving1 ,mechanical4 ,,section ,,iv4 ,,general ,,articles4--,hints to ,lecturers1 by ,andrew ,pringle2 and other articles #djj ,,pages4 ,,numerous ,,illustrations4 ,,price #b_/f2 post free1 #b_/aj-a_/b4 ,london3 ,,iliffe ,,son1 #c1 ,st4 ,bride ,st41 ,ludgate ,circus4 ,,klimsch ,co41 ,,frankfort-,,on-,,the-,,main1 ,,germany4 ,illustration ,,manufacturers ,,and ,,agents ,,for ,,all ,special ,materials ,,and ,requisites ,,for ,,collotype ,,photo-,,lithographic ,,processes4 ,,collotype ,,machines1 ,,rollers1 ,,colors1 ,,inks ,printing and ,transfer ,papers1 c4 ,,we ,,furnish ,,entire ,,studios ,,at ,,advantageous ,,rates ,write for particulars and ,price ,lists4 ,an unequalled guide to the latest ,developments and ,processes4 ,,the ,,international ,,annual ,illustration ,anthonys ,photographic ,bulletin4 ,,edited ,,by ,w4 ,,jerome ,,harrison1 ,f4,g4,s41 ,,and ,a4 ,h4 ,,elliott1 ,,pl4,o4 ,,price #b_/-2 post free #b_/d-a_/b4 ,,iliffe ,,son1 #c1 ,,st4 ,,bride ,,street1 ,,london1 ,e4,c4 ,a ,,great ,,difficulty1 ,and one experienced by all photo-mechanical experimentalists1 has been that of obtaining ,,suitable and ,,reliable material and appliances4 ,a prolonged visit to the best known photo-mechanical establishments of ,austria and ,germany enables us to guarantee that the articles we recommend are the best obtainable for the purposes for which they are supplied4 ,we are in a position to supply-- ,,collotype3 ,collotype ,machines--,hand ,presses--,drying ,boxes--,inks--,varnishes--,printing and ,masking ,papers--,leather1 ,rubber and ,composition ,rollers--,gelatine ,plates--,iron ,beds for ,presses--,printing ,frames--,reversing ,mirrors and ,prisms1 c41 c4 ,,zinc ,,etching3 ,zinc ,plates--,etching and ,tapping ,inks--,rollers--,etching ,boxes--,transfer ,papers--,printing ,frames--,scratch ,papers--,whirlers--,ruled ,tints1 c4 ,,photo-,,litho4 ,,sole ,,agents ,,for ,jaff ,albert's ,transfer ,ink and ,papers4 ,the only ,photo-transfer ,paper to which a ,,gold ,,medal has ever been awarded4 ,,used ,,almost ,,exclusively ,,on ,,the ,,continent4 ,,beesley ,,co41 ,york ,passage1 ,,birmingham4 ,,the ,,photographers' ,,indispensable ,,handbook3 ,a ,,complete ,,cyclop,,dia ,,of ,photographic ,apparatus1 ,material ,,and ,processes ,,compiled ,,and ,,edited ,,by ,w4 ,d4 ,,welford and ,,henry ,,sturmey4 ,this work aims at being for size and weight the most ,,practically ,,useful of any publication on ,photography yet issued4 ,no practitioner1 whether professional or amateur1 whose time is of the slightest value1 should fail to possess a copy4 ,it consists of #dbb handsomely printed pages1 demy #hvo41 and #ejj illustrations1 crammed full of information1 the result of several months' steady labour4 ,descriptions and prices of every photographic accessory1 over #bjj cameras1 #aej lenses1 #dj tripods and stands1 #adj plates1 #dj lamps1 shutters1 complete sets1 burnishers1 special solutions1 etc41 etc41 etc4 ,numerous press and other opinions sent on application4 99 99 99 99 99 8,will prove of great assistance40--,proceedings of the ,camera ,club4 8,the ,laxton of the ,photographer40--,photographic ,news ,almanac4 8,this is an excellent guide to the purchaser of ,photographic ,apparatus40--,the ,camera4 ,,price1 #b_/f2 post free1 #b_/aj-a_/b4 ,,iliffe ,,son1 #c1 ,st4 ,bride ,st41 ,ludgate ,circus1 ,,london1 ,e4,c4 ,,ch4 ,,lorilleux ,,co41 ,printing ,ink ,manufacturers ,,black ,,and ,,coloured ,,varnishes1 ,,roller ,,composition1 ,,etc4 ,,special ,,inks for ,,collotype ,,gold ,,medals4 ,,paris #ahee4 ,,paris #ahgh4 ,,melbourne #ahha4 ,,london #ahhd4 ,illustration3 ,,trade ,,cl ,,mark4 ,,diplomas ,,of ,,honour4 ,,vienna #ahgc4 ,,amsterdam #ahhc4 ,,antwerp #ahhd4 ,,paris3 #af1 ,rue ,suger4 ,,london3 #bg1 ,bouverie ,st41 ,fleet ,st4 ,works3 ,puteaux and ,nanterre4 ,to ,collotypists ,we strongly recommend our ,,rose-,,tinted ,,dull ,,enamel ,,paper4 ,quality the ,best4 ,samples and ,proofs on application4 ,gust4 ,heinr4 ,beneke1 ,lban1 ,saxony4 ,,heinrichs' ,,celebrated ,,gelatines ,,for ,photo-,lithography1 ,collotype1 --,,etc4-- ,a4 ,m4 ,,zimimermann ,,sole ,,agents1 #f #g1 ,cross ,lane1 ,,london1 ,e4,c41 ,or direct from the ,manufacturer-- ,,ch4 ,w4 ,,heinrichs1 ,gelatine ,works1 ,hoechst-on-the-,main1 ,,germany4 -- ,the ,,oldest ,penny ,photographic ,paper in the ,world4 ,,every ,,thursday--,,one ,,penny4 ,,photography3 ,the ,journal of the ,amateur1 the ,profession1 and the ,trade1 ,,is ,,accurate1 ,,newsy1 ,,enterprising4 ,,editorial ,,contributors-- ,capt4 ,w4 de ,w4 ,,abney1 ,c4,b41 ,f4,r4,s42 ,prof4 ,w4 ,k4 ,,burton1 ,c4,e42 ,,george ,,davison2 ,,chapman ,,jones2 ,,andrew ,,pringle2 ,,frank ,m4 ,,sutcliffe4 ,editor--,,henry ,,sturmey4 ,sub-editor--,,walter ,d4 ,,welford4 ,the special features are3--,scientific and ,technical ,articles by well-known writers--,the ,question ,box1 with a series of prizes for the senders of replies--,prize ,competitions--,snap ,shots--,items of ,interest--,interviews with ,prominent ,members of the ,trade2 and the price--,one ,penny4 ,a ,,specimen ,,copy ,,will ,,be ,,sent ,,gratis ,,and ,,post ,,free4 ,,what ,,they ,,think ,,of ,,it3 8,photography is a positive success40--,wilson's ,photographic ,magazine4 8,a stirring1 newsy journal1 which bids fair to a successful career40--,st4 ,louis ,photographer4 8,it is very interesting1 and far ahead of the other photographic papers40--,,gerald ,,stoney1 ,gateshead4 8,i look upon ,photography now as part of my weekly diet1 as it suits my constitution40--,,moore1 ,dartford4 8,when ,i have read the pages of one week's issue ,i am anxious to see the next40--,f4 ,,lewis1 ,derby4 8,your new journal1 like the #8,pickwick' pen1 #8comes as a boon and a blessing to men4'0--,j4 ,c4 ,,christie1 ,old ,cathcart4 8,you may be sure ,i shall prize this1 my first silver medal1 and ,i shall not want to look at it to remind me of ,photography1 as ,i always have this paper for dessert on ,thursdays40--,j4 ,w4 ,,evans1 ,wolverhampton4 8,i think your paper a marvel of cheapness4 ,i had great difficulty in getting it regularly1 or even at all1 at first2 but since ,i have succeeded ,i think all my early trouble has been liberally repaid40--,a4 ,c4 ,,anderson1 ,arbroath4 8,i must say ,photography is proving a decided success2 it seems to be improving every week4 ,since taking in your paper ,i have entirely given up a journal which is published on the same subject1 which1 though more mature in years1 still takes a leaf from its infant friend40--,m4 ,,tillicouthy4 ,london3 ,,iliffe ,,son1 #c1 ,st4 ,bride ,st41 ,e4,c4 ,,and ,,all ,,booksellers ,,and ,,bookstalls ,editorial and ,advertisement ,offices3 ,,vicar ,,lane1 ,,coventry4 ,transcriber's ,note3 ,punctuation has been standardised4 ,spelling and hyphenation have been retained as they appear in the original publication except as follows3 ,page #bf two to three in cm4 width over changed to two to three cm4 in width over ,page #cj on the mercury and quntiaty of air changed to on the mercury and quantity of air ,page #ch may be also used in photo-zylography changed to may be also used in photo-xylography ,page #ig with a mat surface or varnished changed to with a matt surface or varnished ,page #ajc ,the ,artotype ,co4 take changed to ,the ,artotype ,co4 takes ,page #ajg ,if this fail to produce sufficient changed to ,if this fails to produce sufficient ,page #abb we owe the orgination of this changed to we owe the origination of this develope the invisible image changed to develop the invisible image ,page #abf #fj ,reamur changed to #fj ,ramur ,advertisements ,d,,esener ,,weg1 ,,leipsig4 changed to ,d,,sener ,,weg1 ,,leipzig4 ,,leipsic1 ,,germany1 changed to ,,leipzig1 ,,germany1 ,,inks1 ,,rollers1 ,,chemical ,s changed to ,,inks1 ,,rollers1 ,,chemicals ,schweinfurt a_/ ,maine changed to ,schweinfurt a_/ ,main ,a4 ,m4 ,,zmimermann changed to ,a4 ,m4 ,,zimmermann