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THE 
 
 TANNIN PBOCESS. 
 
 
 LONDON: 
 
 JOHN W. DAVIES, 54, PRINCES STREET, 
 
 LEICESTER SQUARE. 
 
 LIVERPOOL: H. GREENWOOD, 32, CASTLE STREET. 
 
 Arthur Jacob Bequest 
 To R. C. S. I. 
 
 1871, 
 
INTBODUCTION. 
 
 The writer has, during the last five years, 
 expended much time and trouble in endea- 
 vouring to discover a really good dry collo- 
 dion process. Having tried every published 
 method which seemed at all promising, he 
 finds that, although nearly all will produce 
 good results if properly managed, yet none 
 are entirely satisfactory. 
 
 The principal faults of the moist preserva- 
 tive processes are — great insensitiveness, un- 
 less an amount of nitrate of silver incompatible 
 with long keeping in hot weather be retained 
 in the film; a difficulty in producing uniform 
 sensitiveness, from the varying quantity of 
 this free nitrate of silver; and a liability to 
 suffer from dust adhering to the surface of 
 
IV. 
 
 the collodion and causing spots. The dry 
 processes hitherto published, besides many 
 other faults belonging to them individually, 
 have one in common — that of being too much 
 dependent for success upon the mechanical 
 state of the collodion. 
 
 The process to be described in the fol- 
 lowing pages is free from the last-mentioned 
 objection, and from many others which attach 
 to other dry processes generally. Although 
 all the experiments necessary to ascertain pre- 
 cisely the best mode of working have not as 
 yet been completed, especially as regards the 
 means of obtaining the greatest degree of 
 sensitiveness, yet it is hoped that the descrip- 
 tion now given will be found sufficient for 
 practical purposes, and that the conclusions 
 which the author draws from his own experi- 
 ments will not mislead. 
 
CHAPTER I. 
 
 ON CLEANING THE PLATES'. 
 
 A draining-stand, which will be found very useful 
 throughout this and other dry processes, may be made 
 in the following manner : — Take a thin board, a little 
 more than three feet long and nine inches broad, and 
 nail another board, sixteen, inches in width, vertically 
 along the middle of the first. Bore vertical holes, 
 
 about one and a half inches apart, along near the 
 edges of the first or horizontal board : fit a number of 
 wooden pegs about two inches long into these holes^ 
 to be used in pairs, in adjacent holes, at such distances 
 as may be required by the size of the glasses used. 
 Nail a leathern strap to serve as a handle on the 
 middle of the upper edge of the vertical board. This 
 stand may be of any convenient size : that described 
 above will take ten stereoscopic plates on each side, 
 
6 
 
 set up diagonally on the corners, and is high enough 
 to drain 12 x 10 glasses in the same position. 
 
 If the plates have been used before, remove the old 
 films by soaking for a short time in a warm solution 
 of carbonate of soda (common washing soda). The 
 plates should be removed from this liquid as soon as 
 the film will come off easily, or the glass may be 
 corroded. The edges may be detached with a knife or 
 with the finger nail, and the remainder of the film 
 rubbed off with the fingers or a hard brush. Then 
 put the plates into a vessel of water, and, having 
 carried them to a pump or tap, wash, in a stream of 
 water, taking care to remove every piece of old film 
 which may remain, and place the glasses on one end, 
 nearly close to the vertical part of the draining-stand, 
 their tops resting against it, the glasses being about 
 half an inch apart. When one row is complete, place 
 the glasses in the next row so that the middle of each 
 covers the interval between two in the first row, that a 
 vent may be left for the escape of damp air upwards. 
 Many dozens of plates may thus be drained at once on 
 the two sides of the stand. Carry the stand into a 
 warm room, and place it before the fire, tilting up one 
 end about six inches to let the water drain away from 
 the lower ends of the glasses. Unless wanted for 
 immediate use, it will not be found worth while to 
 wipe them, if the soda has been well washed off, other- 
 wise this treatment may cause injury by corrosion. 
 
 The edges of new glasses should be ground, and, if 
 
I 
 
 it be intended to dispense with the use of gelatine, or 
 other preliminary coating, the grinding should extend 
 a little way on to the surface. The neatest w*ay to 
 grind the glass in this manner is with a piece of stout 
 sheet copper, along the middle of which has been sol- 
 dered a narrow strip of the same metal about one- 
 sixteenth of an inch thick ; on the other side a piece 
 of wood may be screwed, to give a better hold. Mix 
 some silver sand, brown sugar, and water, and, with a 
 little of this mixture in the angle, rub the thick cop- 
 per against the edge of the glass, at the same time 
 grinding the upper surface with the lower edge of the 
 thin strip. The plate is held down with the left hand 
 on a piece of wood or other convenient place, with the 
 edge that is being ground slightly projecting : if it 
 project far, the glass may be broken. The edge and a 
 narrow strip of the surface can in this way be ground 
 without rounding off the angle. The use of the sugar 
 is to render the dirt more easy to wash off. If the 
 plates are to be coated with gelatine it is better to 
 grind only the edges, for the ground glass impedes the 
 flow of the gelatine, and is not in this case required to 
 make the film adhere. The edges should be slightly 
 rounded in grinding, to facilitate picking up the glasses 
 out of a dish. 
 
 After being ground the plates must be well washed 
 to remove grit, and drained dry as described above, 
 before being placed in contact with each other. When 
 dry they may be piled one upon another in the place 
 
8 
 
 where they are to be cleaned. Any mode of cleaning 
 will answer which ensures the removal of all traces of 
 grease as well as other impurities. The method now 
 to be given is as certain and as little troublesome as 
 any. Two rubbers are required, which are to be con- 
 structed as follows : — For the first, take a piece of 
 thick felt, well cleaned with warm water and soda, 
 and then with water only, and, when dry, cement it 
 flat on a bung about three inches in diameter — a 
 solution of shellac in naptha, or of india-rubber in 
 turpentine, will answer as the cement — and the bung 
 should then be laid, felt downwards, on a flat surface, 
 and left with a weight upon it for some hours, after 
 which the edges may be trimmed. Mix a little tripoli 
 with water in a phial; shake up, and allow it to stand 
 a few minutes, that the coarse grains may subside; 
 then well wet the felt with the turbid water, and dry. 
 This rubber will last for years, and will never require 
 anything more to be done to it if kept clean. The 
 other rubber is made by nailing a piece of cotton velvet 
 (cleaned in the same way as the felt) to the edges of a 
 piece of board about four inches wide, and a little 
 longer than the width of the largest glasses to be used. 
 The lower edges of the board should be rounded off, 
 and three thicknesses of coarse flannel laid on it before 
 nailing on the velvet. A strap of webbing or leather 
 nailed to the edges across the back will make a handle. 
 This rubber, like the other, will last for a long time, 
 as it may be used until the pile is worn off; it will 
 
9 
 
 require no cleaning, but may be brushed occasionally 
 with a hard brush kept for this purpose only. Put it 
 away in a dry place, with the velvet downwards, on a 
 clean piece of blotting paper. 
 
 Liquids sold for cleaning glasses often contain rouge 
 and nitric acid, both of which are objectionable — the 
 rouge adhering to the glass so firmly as to be difficult 
 to clean off, and a trace of nitric acid sometimes 
 remaining in a scratch causing a mark of insensitiveness 
 in the negative. Old collodion — the older the better — 
 mixed with tripoli, answers well. The collodion should 
 be diluted with an equal quantity of common alcohol, 
 or, what is better, methylated spirit ; and if it is not 
 already of a red colour, iodine should be added to 
 bring it to a port-wine tint. A tripoli mixture ought 
 always to be shaken up, and then allowed to subside, 
 that the coarser grains may sink to the bottom : before 
 using, shake till slightly turbid. Choose a place where 
 a slight current of air will carry off the vapour from 
 the eyes, or it may make them smart. 
 
 Put the glass to be cleaned in a screw holder, rub 
 the back over slightly with a tuft of cotton wool and a 
 few drops of the cleaning fluid, then wipe dry with 
 a cloth, turn over and fix again with the screw ; 
 breathe on the front, and rub with the cotton wool; 
 drop on a little of the mixture and rub over again. 
 When by repeated use the tuft of cotton wool becomes 
 so hard as not to be immediately softened by the liquid, 
 it should be rejected, or the glass may be scratched. 
 
10 
 
 Wipe the edges of the glass with the cloth, to remove 
 free iodine which may have gone over the angles, and 
 would injure the exciting bath ; then place the plate 
 against a bottle, in a nearly vertical position, on a piece 
 of clean paper, and proceed in the same manner with 
 the other glasses, except that after the first, the collodion 
 need only be dropped on the fronts : a drop or two on 
 each will he quite enough when the cotton is once wet, 
 if the glasses are small. By cleaning the backs slightly, 
 we not only avoid introducing impurities into the bath, 
 but prevent waste of the nitrate solution, which, if the 
 glass be at all greasy, will adhere in drops instead of 
 draining off. Next take the plates one by one, place 
 again in the screw holder, face upwards, breathe very 
 slightly on the surface, and polish off the collodion mix- 
 ture with the felt rubber till quite dry This will take 
 but a few seconds, and will leave the plate quite clear of 
 everything except slight traces of tripoli dust on the 
 surface, and of the cleaning fluid in the pores of the 
 glass. * The dust should be brushed off with cotton 
 wool, and its entire removal ensured by polishing with 
 the velvet rubber: leather must not be used, as, however 
 carefully cleaned, it always leaves on the glass a trace 
 of greasiness which will repel the gelatine solution. 
 Place each plate, as soon as finished, vertically on the 
 draining-stand, and when all have been cleaned, brush 
 the velvet rubber to remove dust. 
 
 * See remarks at page 59 on the effect of iodide and iodine 
 on silver stains. 
 
CHAPTER II. 
 
 COATING WITH GELATINE. 
 
 Gelatine, simply dissolved in water, is always slightly 
 milky, and the impurity, whatever it may he, is not 
 removable by filtration, but soon clogs the paper. 
 If a glass be covered with the milky solution, the white 
 substance, when dry, appears like a fine dust adhering 
 to the surface of the gelatine, and unless polished off 
 by hard rubbing, sometimes shows slightly in the 
 transparent parts of the negatives. These incon- 
 veniences may be entirely avoided in the following 
 manner : — Soak the gelatine in distilled water, two to 
 five grains to the ounce, adding one drop of glacial 
 acetic acid for each grain of gelatine. When thoroughly 
 swelled and transparent, dissolve by warming. Should 
 the water be heated before the gelatine has had time 
 to swell, the latter will adhere to the bottom of the 
 vessel containing it, in a stiff glutinous state, and will 
 dissolve with great difficulty. Add one drachm of pure 
 or methylated alcohol to each ounce of solution, and 
 filter two or three times through filtering paper in 
 a warm place. The acetic acid coagulates the white 
 impurity, which then collects into filaments, and is 
 removed by filtering, leaving the solution very bright. 
 This solution will keep for a long time ; but, should it 
 
12 
 
 decompose from loss of alcohol by evaporation, it must 
 be rejected. Any decomposition may be detected by a 
 disagreeable smell, and by the solution becoming limpid. 
 
 A two-grain solution of gelatine scarcely requires 
 warming to work well, if the temperature of the room 
 is not much below sixty degrees. Gelatine liquid of 
 this strength answers well with a thin collodion ; but, 
 when the collodion is thick, it is apt to fail, by allowing 
 the film to loosen during development, which is fatal 
 when gelatine is used, although not necessarily so in 
 the case of simple uncoated glasses. It is therefore 
 advisable to use the gelatine solution strong enough. 
 A five-grain solution may be depended on for producing 
 sufficient adhesion, whatever be the nature of the 
 collodion, and gives but little extra trouble in pre- 
 paration. The strength of the gelatine solution ought 
 certainly to be proportioned to the thickness of the 
 collodion film ; but, nevertheless, considerable latitude 
 is admissible — so much so, that any solution containing 
 between two and five grains to the ounce will answer 
 in the majority of cases. The effect of using too little 
 gelatine is insufficient adhesion; of using too much, 
 blueness of the film, general insensitiveness, and want 
 of vigour in the negative, from the penetration of the 
 gelatine to the surface of the collodion. Should this 
 penetration be uneven, markings of insensitiveness 
 will be the result.* A solution of isinglass may be 
 * The writer has not seen these faults except when using a 
 ten-grain solution of gelatine, or a five-grain solution of isinglass, 
 for experiment. 
 
13 
 
 substituted for that of gelatine, if of about half the 
 strength, that is from one to two and a half grains to 
 the ounce ; but it does not appear to make the film 
 adhere quite so strongly to the glass. Isinglass may, 
 however, possibly answer better than gelatine in very 
 hot weather, as the former remains undissolved at a 
 higher temperature than the latter. 
 
 Should there be a fire in the room, place the draining 
 stand before it on a chair rather than on the floor, for 
 obvious reasons. The glasses should all be on the 
 side of the stand next the fire, and the distance from 
 it such that they will bedome a little warmer than the 
 hand. 
 
 Whatever method of applying the gelatine be adopted 
 the plates must be warmed after cleaning, or traces of 
 the cleaning liquid, remaining in the pores of the 
 glass, will repel the solution, causing circular spots 
 of bare glass to appear on draining. Warm the 
 gelatine by putting the bottle, which should be thin, 
 inside the fender, or more quickly by dipping it in 
 hot water, taking care not to immerse beyond the 
 surface of the solution, or the bottle may be broken. 
 Take a small cylindrical glass vessel called a beaker 
 (the best are those which have the rim most turned 
 out) and a glass funnel. The nose of the funnel may, 
 if necessary, be shortened by notching with a file, 
 and breaking to such a length as to be just clear 
 of the bottom when the cone fits the upper part of 
 the beaker. The broken end should be ground smooth 
 
14 
 
 on a grindstone, or other rough stone, to prevent risk 
 of scratching the plates. 
 
 Cut a piece of new fine-grained sponge into a trun- 
 cated conical shape, the outside forming the thicker end, 
 to he placed upwards. Soak in water, and knead well 
 under a tap to remove loose particles ; push rather tightly 
 into the neck of the funnel ; then pour in enough gelatine 
 solution to stand in the beaker higher than the top of 
 the sponge in the funnel : it will pass through quickly. 
 
 Take up a glass with a pneumatic holder, sweep 
 with the velvet rubber, and place on a levelling 
 stand with the holder still attached. If the plate 
 be large the holder should be in the middle, if of 
 stereoscopic size close to the edge of the plate, 
 when there will be room for it if the levelling stand 
 be of suitable size (about 6J inches between 
 
 
15 
 
 the screws at the corners), the glass resting on 
 two of the screws in the middle of the sides of the 
 triangle, and on the screw at the angle nearest the 
 operator. Take the funnel in the left hand, and 
 hold nearly or quite in contact with the surface of the 
 plate near corner 1 ; then with the right hand pour 
 the solution from the beaker on the same corner, 
 nearly touching the surface of the plate with the rim, 
 to avoid making bubbles, until about a quarter of the 
 glass is covered ; then replace the funnel in the beaker 
 hold in the left hand under corner 4, and, taking the 
 holder in the right hand, lift the end of the plate on 
 which the solution has been poured in such a manner 
 that it will flow to the left, inclining from side to side 
 to keep the advancing edge of the liquid convex until 
 the plate is covered ; then pour off into the funnel 
 from corner 4. With a little practice this operation is 
 quite as easy as pouring the collodion, the solution 
 flowing very readily on glasses cleaned as described 
 above. 
 
 Should any difficulty be found at first, the gelatine 
 may be spread with a glass rod bent at one end, which 
 may be placed ready for use in a clean glass measure, 
 or the flow of the solution may be assisted with the 
 nose of the funnel. It is better to dispense with the 
 use of the glass rod, as dust may fall on it and so be 
 introduced into the solution and left on the plate. 
 This would render a second pouring on and off neces- 
 sary. Next set the plate up to drain on corner 3, 
 
16 
 
 between two of the pegs of the draining stand on the 
 farther side from the fire, taking care that the glass 
 rests against both pegs, to ensure its standing firmly. 
 Blotting paper should previously have been placed 
 between the pegs to absorb the liquid ; a piece about 
 two inches square, folded in equal parts three times, so 
 as to give eight thicknesses, will be enough for a stereo- 
 scopic plate. If the glasses are drained on the side 
 next the fire, a hard line will be formed near the two 
 lower sides, like that produced in drying by the thick 
 edges of negative varnish : this line would show in the 
 picture, but is never formed when the gelatine is 
 allowed to dry spontaneously. Proceed in the same 
 manner with the other glasses : if these are slightly 
 warm the gelatine will be kept sufficiently fluid. 
 When too warm, the solution becomes limpid, and does 
 not flow T regularly, leaving also a thinner film upon the 
 glass. The best consistency is about that of iodized” 
 collodion. 
 
 Should it be preferred, the gelatine can be poured 
 exactly in the same manner as collodion, without a 
 levelling stand, by using two beakers, and placing the 
 funnel in one, while the solution is poured on the plate 
 from the other. In this case, after returning the liquid 
 from the plate into the glass, pour it into the funnel to 
 remove dust. 
 
 One side of the draining stand will he filled with 
 gelatinized plates long before the first has had time to 
 dry; therefore if more are to be coated they must be 
 
17 
 
 placed to drain elsewhere. In taking up the glasses 
 to cover with gelatine clear one end of the stand first, 
 and when the gelatinized plates appear to be dry, ex- 
 cepting at the lowest corner, place them on the side 
 next the fire, at the end cleared by their previous 
 removal. When all the uncoated glasses have been 
 removed from the stand the coated ones should be 
 spread along, in the manner described after washing 
 the glasses, to complete the drying by heat. 
 
 The above plan will answer well if a place near a 
 fire can . be found sufficiently free from dust. The 
 plates being drained with their faces inwards are not 
 very easily affected in this way, but care should be 
 taken that no dust, especially from fishes, comes in 
 contact with the surface when wet, in any stage of 
 preparation : when dry this is of little consequence, 
 as it can be brushed off again. Should it be found 
 desirable to perform this part of the process in a cold 
 room without a fire, a simple warming apparatus may 
 be extemporised in a few minutes thus : place a Childs 
 night light in a gallipot lid containing a little water, 
 put on each side of the light a piece of wood about 
 half an inch higher than the top of the flame, cut a 
 piece of tin with an old pair of scissors (a piece of any 
 kind of canister will do), long enough to reach from 
 one piece of wood to the other, and a little wider than 
 the glass which contains the gelatine solution. Should 
 the tin not be sufficiently rigid it may be made so by 
 turning up the edges ; this will at the same time 
 
 B 
 
18 
 
 prevent the glass slipping off. Having warmed the 
 solution to commence with, after coating each plate 
 place the beaker on the tin over the light whilst 
 setting up that plate to drain and taking up another : 
 this will keep the solution quite fluid enough. 
 
 By adding more acetic acid, the gelatine may be used 
 in a cool place without any artificial warming. One 
 drachm of glacial acetic acid to seven drachms of water, 
 or an equivalent proportion of weaker acid, and five 
 grains of gelatine, will work in this way ; but in such 
 a case the plates must be quite cold, or the solution 
 will be rendered too limpid. This plan is not quite so 
 safe as that described before, but will answer well if 
 the plates are heated pretty strongly for some time to 
 complete the drying. Acetic acid does not change the 
 gelatine into metagelatine like some other acids, but 
 merely acts as a solvent, and being volatile is easily 
 driven off by heat. The acid, if not thus removed, 
 would cause solution of the gelatine during the subse- 
 quent exciting and washing. 
 
 The previous coating of gelatine is peculiarly suited 
 to this process, as the tannin solution, when concen- 
 trated by drying, coagulates the gelatine partially, if 
 not entirely, so that it holds to the glass with great 
 firmness, and cannot afterwards be loosened by any 
 amount of washing, provided an alkaline liquid be not 
 applied to the film. The working of the gelatine will 
 be found very easy and certain in practice if done as 
 described above. The plates can be coated and set up 
 
19 
 
 to drain at the rate of more than one per minute, and 
 unless dust fall on the surface between the pouring off 
 of the solution and setting up to drain, a speck will 
 never be seen on the film. 
 
 The gelatinized plates will remain good any length 
 of time if kept perfectly dry. To secure this, after 
 thoroughly desiccating by heat, pack the glasses face 
 downwards (except the lowest glass which should have 
 its face up), with a strip of blotting paper at each end 
 folded like a fan, a fold being inserted between each 
 plate and the next, beginning with the lowest and 
 working upwards. The glasses may then be stored in 
 a tin box, into which should also be put a lump of 
 quicklime, folded in thick filtering paper and tied 
 round with string. The inside of the box and the 
 strips of blotting paper should be previously warmed 
 to ensure dryness. The gelatinized plates may be 
 kept in a common grooved box, if in a very dry place ; 
 should they be put away damp, or should moist air 
 get access to them afterwards, mould would form on 
 the gelatine, which would show in round black spots 
 on the negative. 
 
 It will be found practically that it is much easier to 
 produce perfectly clean negatives with the gelatine 
 than without it, and that this coating has the further 
 merit of effectually masking slight scratches and 
 defects in the glass, to say nothing of the advantage 
 of rendering success independent of the mechanical 
 condition of the collodion. 
 
7 
 
 20 
 
 The gelatine does not appear to injure the bath for 
 use in this process, or in all probability for any other 
 process in which the whole of the nitrate of silver is 
 removed by washing : a bath in which gelatinized 
 plates had been excited for months, was found to pro- 
 duce negatives quite as bright and vigorous as if 
 freshly made, although no precautions had been taken, 
 such as wiping the backs of the glasses to remove 
 gelatine. So little indeed was this bath injured that 
 it would produce brilliant and vigorous negatives by 
 the wet process when a collodion containing a large 
 proportion of bromide was used ; the plates excited in 
 it showed no tendency to fogging, and resisted solari- 
 zation remarkably well. Should it however be desired 
 to prepare plates for this process in a wet collodion 
 bath without injuring it, at the same time securing all 
 the advantages of the gelatine coating, a plan will be 
 described in the concluding chapter which at the cost 
 of a little more trouble will fulfil these conditions, 
 and give even greater adhesion. 
 
 It is not absolutely necessary to use any preliminary 
 coating, as the process, with many samples of collodion, 
 can be worked without such precaution. The glasses 
 should in this case, as before stated, be ground a little 
 way on the surface, and if the film even then shows 
 signs of slipping off, the extreme edge must be painted 
 round with thick quick-drying spirit varnish when dry. 
 This operation may be conveniently performed in the 
 following manner : — Bore a hole vertically through the 
 
2 ] 
 
 cork of a one-ounce phial, and insert firmly a small 
 cylindrical piece of wood, about two thirds as long as 
 the height of the phial ; tie a small camel’s hair brush 
 to the wood, in such a position that the latter projects 
 half an inch or so beyond the point of the brush ; keep 
 the phial about half full of negative varnish from a 
 bottle which has been nearly used out, that it may be 
 thick enough to prevent splashing ; the brush, being 
 kept in the bottle with the varnish, will always remain 
 soft. To varnish the edges of a plate, take it up with 
 a pneumatic holder, and draw the brush round, the 
 wood acting as a guide against the edge of the glass, 
 so as to varnish only a strip one-eighth of an inch 
 wide or less. If the plates are to be used for print- 
 ing transparencies on, the edges should not be var- 
 nished till after exposure, or the thickness of the 
 varnish will prevent contact of the plate with the 
 negative. 
 
 On wetting the film previous to development in 
 this mode of working, the collodion will probably 
 expand 1 strongly, so as to be forced up into ridges all 
 over the plate, but sometimes it will contract again in 
 the course of ten or fifteen minutes. The development 
 must not be proceeded with until the contraction has 
 taken place, or the fluid will get under the wrinkles 
 and produce narrow dark lines in the negative. Should 
 the film contract enough to lie smoothly it will not 
 become loose again, and when dry will adhere firmly 
 to the glass ; but sufficient contraction does not take 
 
22 
 
 place with some kinds of collodion, and hence this 
 mode of working is open to the objection of making 
 success dependent on the mechanical state of the 
 collodion. 
 
 Even when quite successful, this mode of proceeding 
 involves quite as much time and trouble as when 
 gelatine is used, especially if the edges require to 
 be varnished. The character of the picture will not 
 be very perceptibly different whether gelatine be used 
 or not; and, with the exception of the precautions 
 described above, the treatment may be the same 
 throughout in either case. 
 
CHAPTER III. 
 
 COLLODION, EXCITING AND WASHING. 
 
 x4.lmost any collodion will produce good results with 
 tannin if properly managed, no matter how new and 
 horny, or how old and rotten. Even should it be too 
 old or too new to work well in the wet process, it will 
 still succeed. Some difference will, however, be found 
 in the character of the resulting pictures, though not 
 so great as in the wet process, and there will be a great 
 difference in the sensitiveness. A new collodion is 
 the most sensitive, and in the writer’s hands gives the 
 proper red tone and vigour of negative perfectly, 
 provided a strong solution of tannin be used. An 
 old and powdery sample, on the other hand, even if 
 rendered colourless by cadmium, besides being very 
 insensitive, gives a pale grey image which will not 
 develop with quite so much vigour and richness of 
 tone, and the film when varnished is soft and liable 
 to injury, whereas that produced by a new and horny 
 collodion is, in hardness and durability, only inferior 
 to albumen. A tolerably opaque film is advantageous, 
 but not so necessary as in other dry processes, plates 
 
24 
 
 prepared with tannin being little liable to solarization. 
 Opacity should not be obtained by over-iodizing the 
 collodion, but by using a thick sample. 
 
 Simply iodized collodion may be used, but the 
 presence of bromide greatly increases sensitiveness, 
 intensity, and facility of development. Any collodion 
 which is sensitive and gives good results in the wet 
 process may be rendered suitable for use with tannin 
 in the following manner : — Dissolve sixteen grains of 
 bromide of cadmium and four grains of bromide of 
 ammonium in one ounce of alcohol s.g. *805 : if the 
 collodion is not iodized, mix three parts of this solution 
 with five parts of the iodizing solution, and to one part 
 of the mixture add three parts of plain collodion. If 
 the collodion is already iodized, add three parts of 
 plain collodion to one part of bromide solution, and 
 mix three parts of this bromized collodion with five 
 parts of iodized collodion. 
 
 Positive collodion will require less bromide, as it 
 usually contains some already; but the exact propor- 
 tion of iodide and bromide is not of much importance. 
 The addition of bromide of cadmium to collodion 
 iodized with iodide of potassium, produces by double 
 decomposition iodide of cadmium and bromide of 
 potassium : the former impairs the fluidity of the 
 collodion, and the latter, being nearly insoluble in 
 strong alcohol, is almost all precipitated. If therefore 
 the presence of iodide of potassium is shown by 
 turbidity on the addition of bromide, it will be better 
 
25 
 
 to dissolve about two parts of bromide of ammonium 
 and one part of bromide of cadmium in the smallest 
 possible quantity of alcohol s.g. *816, and to add this 
 solution cautiously until turbidity is produced. The 
 collodion will he found to be very little altered in 
 fluidity and stability, and, when cleared by subsidence, 
 to have retained enough bromide to improve it greatly 
 for this purpose. 
 
 Should any doubt be entertained as to the good 
 effect of so large a proportion of bromide as that 
 recommended above, it may be easily removed by 
 experiment. Prepare thirty-six drachms of iodized 
 and eighteen drachms of bromized collodion in two 
 bottles, the iodide and bromide being in the same 
 proportion in both, and the same plain collodion being 
 used in both cases. Coat and excite one plate or 
 more with the iodized collodion; then mix half a 
 drachm of bromized with four drachms of iodized col- 
 lodion in a small bottle, and proceed as before ; pour 
 away into another bottle, and mix one drachm of bro- 
 mized with four drachms of iodized collodion, and so 
 on, increasing the proportion one eighth part each 
 time until equal quantities have been used. We shall 
 now have nine differently constituted sensitive layers, 
 varying by one-eighth in each case, from all iodide to 
 equal parts of iodide and bromide. The residues, if 
 all poured into one bottle, will be found to do very 
 well for ordinary use. The plates, after being pre- 
 pared with tannin, are then to be exposed a minimum 
 
26 
 
 time in a uniform light, using the same subject, and 
 developed in the same manner, when it will he found 
 that there is a rapid and regular improvement up to 
 three parts of bromide to eight of iodide, and that 
 further addition of bromide makes but little difference 
 up to equal parts of each. Three parts of bromide to 
 five of iodide will probably give about the best result; 
 and it will be seen that this proportion leaves an 
 ample margin both ways, to allow for disturbing causes, 
 suqh as a little bromide or an uncertain amount of 
 iodide in the collodion, if of unknown composition. 
 The different proportions of iodine and bromine in 
 various iodides and bromides, and peculiarities in the 
 quality of the pyroxyline, might slightly affect the 
 quantity of bromide required to give the best result. 
 The use of a large quantity of bromide has a tendency 
 to diminish the opacity of the excited film. Should 
 this effect be produced to too great an extent, a little 
 more iodide and bromide may be added in the proper 
 proportion to the collodion. Bromide may not pro- 
 duce so marked an effect if a trace of nitrate of silver 
 be left in the film ; but, even if the presence of nitrate 
 with the tannin appears to answer the same purpose 
 as bromide, the use of the latter and the entire 
 removal of the nitrate is for many reasons a preferable 
 mode of treatment. 
 
 If the collodion be purposely prepared for use on 
 gelatine with tannin, the following will be found to be 
 a good formula : — 
 
27 
 
 Iodide of ammonium 2 grains. 
 
 Iodide of cadmium 1 „ 
 
 Bromide of cadmium 2 „ 
 
 Pyroxyline, prepared by Hardwich’s 
 formula for negatives by the wet 
 
 process 
 
 Alcohol, sp. gr. *805 4 drachms. 
 
 Ether (the best which can be procured). 4 „ 
 
 This collodion will require to be diluted with more 
 alcohol and ether if used to coat large plates. The 
 salts of cadmium give great stability to the collodion, 
 and are very soluble in highly rectified alcohol; but 
 they render the collodion so thick as to be ill adapted 
 for producing a good uniform film on a large plate. 
 Iodide of ammonium has an opposite effect, rendering 
 the collodion unstable, but very fluid ; hence, by using 
 different proportions of the iodides and bromides of 
 cadmium and ammonium, we can vary the quality of 
 the collodion in the above respects at will. 
 
 The iodide and bromide of potassium are inter- 
 mediate in their effect on the stability and fluidity of 
 the collodion, and stand between these of cadmium 
 and those of ammonium ; they are, however, less 
 soluble in strong alcohol than either. Should it be 
 desired to give the collodion more fluidity than that 
 produced by the above formula, a larger proportion of 
 the ammonium salts may be used; but this cannot 
 be carried beyond a certain point, unless a portion of 
 
28 
 
 the alcohol be in a state of greater dilution with 
 water.* 
 
 In all cases it is desirable, when much bromide is 
 used, to employ a large proportion of the bromide of 
 cadmium , on account of its great solubility in strong 
 alcohol. The proportion of ether and alcohol is of no 
 importance in this process, beyond its being such as is 
 found to produce the most uniform and perfect film. 
 The greater the quantity of water present, the larger 
 must be the proportion of ether to work well. The 
 proportion of ether required is also dependent on the 
 quality of the pyroxyline : it should be large enough 
 to render the film somewhat horny and free from mot- 
 tled markings. 
 
 Almost any nitrate of silver bath will answer, if 
 slightly acid, and not below the strength of thirty 
 grains to the ounce. A neutral or alkaline bath will not 
 succeed, being liable to cause fogging, and after this 
 commences the half-tones will not develop. Hence 
 a slightly acid bath may be said to give greater 
 sensitiveness, although an excess of acid beyond what 
 is necessary to keep the picture clear will greatly 
 diminish sensitiveness. The following method of pre- 
 paring a bath will be found as good as any for this 
 process : — Dissolve and iodize in the usual way thirty- 
 five or forty grains of nitrate of silver for each ounce 
 
 * The soft and granular kind of iodide of ammonium is 
 better than that which is sold in hard crystals — the former, 
 though less' stable, being more soluble. 
 
 ■■■ 
 
29 
 
 of water, stir in a very small quantity of bicarbonate 
 of soda to ensure the absence of nitric acid (if the 
 nitrate of silver be alkaline this will be unnecessary), 
 filter, and then render slightly acid with acetic or citric 
 acid. 1‘f the latter be used, about two drops of a 
 solution, ten grains to the ounce, will he required for 
 each ounce of the bath, or more if the nitrate be 
 decidedly alkaline. 
 
 The bath should be acid enough to redden test-paper 
 immediately. It is better to add too much acid than 
 too little, inasmuch as a slight loss of sensitiveness is 
 better than risk of fogging.' If citric acid be used it 
 will probably precipitate some of the iodide of silver; 
 and if so, the solution must be filtered again. Should 
 plates, otherwise properly treated, show the least sign 
 of fogging, more acid must be added. A more acid 
 bath will be required for use with a nearly, or quite, 
 colourless collodion than with a sample coloured with 
 free iodine. 
 
 A rather strong bath is better than a weak one when 
 a thick and highly idodized collodion is employed, and 
 in all cases saves time by exciting more quickly. After 
 the bath is once prepared, if only used for this process, 
 it never need be filtered again, as any sediment which 
 may settle on the surface of the collodion will be 
 removed by the subsequent washing. 
 
 The plates are to be coated with collodion and excited 
 in the usual manner, and washed, first in distilled water, 
 and afterwards in common water. The following will 
 
30 
 
 be found to be a good way of managing these opera- 
 tions : — Fill two dipping baths with distilled water, and 
 one or more gutta percha trays, or other convenient 
 vessels, with common water, and place all near the 
 exciting bath. Take up a plate with a pneumatic 
 holder, and rub the surface with the velvet rubber to 
 remove any slightly adhering particles of dust, turning 
 in such a direction that the slight current of air which 
 exists in almost every room may carry dust away from 
 the place where the plate is to be coated. A common 
 one-ounce, two-ounce, or three-ounce phial, according 
 to the size of the plates, is better than the bottles 
 usually made for the purpose of pouring collodion, 
 since the cork keeps the neck much cleaner than a 
 glass stopper, and prevents the formation of dried or 
 half-dried fragments. Take out the cork, and wipe the 
 rim before commencing. It will be better not to wipe 
 it again while coating plates in rapid succession, care 
 being taken to pour from the same side of the rim 
 every time. The bottle should be kept nearly full, by 
 adding from another bottle every few plates, or any 
 sediment at the bottom will be disturbed. The collo- 
 dion in the second bottle should be thinner and contain 
 more ether, according to the size of the plates, to allow 
 for evaporation and keep it in the same state. Coat in 
 the usual w T ay, pouring off, by preference, from the 
 same corner on which the glass was drained after being 
 gelatinized, that the thickest part of the collodion may 
 be on the thickest part of the gelatine. 
 
31 
 
 Take the plate off the holder as soon as the collodion 
 has ceased to flow, still keeping that side downwards 
 which was lowest in pouring off, and tilting it at a com 
 siderable angle on the edge of the screw-holder, or 
 other convenient place, to prevent the thick edge 
 spreading hack on the plate. Touch the thick edge 
 to ascertain when set enough, which is known by its 
 just taking the impression of the finger. The film 
 need not be more set than for the wet process, when 
 gelatine has been used. If the plate be not quickly 
 removed from the holder, the excited film will show a 
 circle of greater transparency where it was attached. 
 This mark is caused by difference of temperature, 
 and the effect is produced very quickly when the 
 glass is thin. 
 
 When the film is sufficiently set, immerse in the 
 bath, and give the plate a lateral circular motion for a 
 few seconds, to prevent streaks in the direction of the 
 dip and to hasten the action. Take up another plate 
 on the holder, rub as before, and lay it down until 
 required: After about two minutes lift the plate in 
 
 and out of the fluid ten or twelve times, until the oily 
 lines disappear ; then sweep the next plate gently once 
 or twice with the rubber, coat with collodion, and tilt 
 up to set, as before. Now take the first plate out of 
 the bath, drain the lowest corner for a few seconds 
 against the dipper, and place in the first bath of dis- 
 tilled water. This operation will usually occupy about 
 as much time as the next plate requires to set: touch 
 
32 
 
 the thick edge to ascertain if ready, and immerse in 
 the bath. 
 
 Should the temperature be very high, a quickly- 
 setting collodion may not allow of this way of working, 
 the film becoming too dry, as shown, after excitement, 
 by the transparency of the edges which were uppermost 
 when the collodion was poured off. In such a case the 
 first plate must be removed from the bath before the 
 second is coated ; but the plan above described will be 
 generally practicable, and saves much time. After the 
 second plate is in the bath, the first is removed from 
 distilled water No. 1 into distilled water No. 2. 
 
 Proceed in the same manner throughout : that is, 
 after immersing each plate in the exciting bath, pick up 
 the next and rub the surface ; then lift the plates up 
 and down in both distilled water baths a few times ; 
 then shift the plate in No. 2 into the common water, 
 and lift the edge of the dish to make the water flow 
 over it. Next remove the plate from No. 1 into No. 2, 
 just made vacant ; lift the plate in the nitrate bath till 
 oiliness disappears; cover the next with collodion , and 
 so on till all the plates to be prepared are in the com- 
 mon water, where they may remain for hours without 
 injury. 
 
 The distilled water need not be changed until a 
 considerable number of plates have been washed, 
 when the second bath may be substituted for the 
 first, which is then to be emptied and filled with fresh 
 distilled water. If dipping baths are not at hand, 
 
33 
 
 horizontal dishes will answer the purpose; and, if 
 large enough to hold several plates, the first dish may- 
 be filled before removing each plate in its turn to the 
 second dish. When the second is full, the plates should 
 he placed in the same manner in the common water. 
 The washing in distilled water is necessary when 
 the common water is hard, to prevent violent decom- 
 position of the nitrate by the action of the salts in the 
 hard water, and consequent precipitation and adhesion 
 to the film of insoluble salts of silver. The whole of 
 the above described operations can he conducted whilst 
 the plates are exciting in the bath ; and, since a second 
 plate is always put into the bath as soon as the fully 
 sensitized one is taken out, no time is lost. Twelve 
 plates can thus he easily excited and washed in an 
 hour, or in less time if the bath be very strong. The 
 plates prepared for any dry process require a rather 
 longer stay in the exciting bath than would be neces- 
 sary for the w r et process, as in the latter case the 
 action of the nitrate, if not quite complete, will go 
 on after the removal of the plate, the solution being 
 left on the film. The plates should not be less than 
 half an hour in the common water : unless the latter 
 be very unusually pure, the small trace of nitrate left 
 in the film will be entirely removed in that time. 
 Should the water be too pure to precipitate nitrate 
 of silver, it may be used instead of distilled water for 
 the first and second washing baths, and have a very 
 small quantity of salt dissolved in it for the third, 
 c 
 
34 
 
 After being washed in common water, the plates 
 may be steeped in strong salt and water, if thought 
 desirable, without perceptible alteration of quality in 
 any way, provided the salt be entirely removed. No 
 economy of time, however, results from this mode 
 of working ; on the contrary, it takes a longer washing 
 to remove the salt than is required for the nitrate of 
 silver, since the former is acted on only mechanically, 
 the latter chemically as well, by hard water, A very 
 small trace of chloride of sodium remaining in the 
 film will greatly diminish vigour and intensity in the 
 picture. 
 
 By the time that six plates have been put into com- 
 mon water the first will be ready to be coated with 
 tannin ; but, if as many as a dozen or two are to be 
 prepared, it will be found more convenient to finish 
 one operation before commencing another, and greater 
 security will thereby be afforded against the presence 
 of traces of nitrate, the entire absence of which is of 
 great importance. It will be as well to cover the 
 vessels containing the common water with large gutta 
 percha trays, to keep out light and dust while the 
 excited plates are being washed. 
 
CHAPTER IY. 
 
 COATING WITH TANNIN. 
 
 Commercial tannin appears to be very uniform in 
 its action, but some samples contain more insoluble 
 resinous matter than others. This impurity is not 
 injurious, but it increases the difficulty of preparing 
 and filtering the liquid. The solution may be of any 
 strength, from ten grains to thirty grains to the ounce 
 of water, and within these limits will give good results 
 with any kind of subject. The stronger the solution, 
 however, in the case of a sensitive and newly iodized 
 collodion, the redder the image at the commencement 
 of development, and the richer and more vigorous 
 the picture — especially so when the subject is badly 
 lighted. If the plate is to be used for a landscape 
 containing dark foliage and sky in a good light, or for 
 any other kind of subject which gives great contrast of 
 light and shade, a strong solution of tannin on a new 
 and sensitive collodion causes a development so ener- 
 getic and rapid as to be rather difficult to control. It 
 will therefore perhaps be better in such cases not to 
 exceed fifteen grains of tannin to the ounce, and not 
 to use a very freshly iodized collodion — at any rate 
 until some familiarity with the process has been 
 gained, especially as regards the management of the 
 
86 
 
 development. If less than ten grains to the ounce be 
 used on a sensitive collodion, the image is apt to he 
 feeble and slow of development. The strength of the 
 tannin solution within the above limits does not per- 
 ceptibly affect the adhesion of the film to the glass 
 when gelatine has been used. 
 
 Weigh out a quantity of tannin sufficient to fill three 
 common one-ounce, two-ounce, or three-ounce phials 
 with solution of the strength preferred. The third 
 bottle may be larger than the others, to avoid the 
 trouble of often making fresh solution. Mix the 
 tannin with the quantity required of distilled water 
 in a glass vessel, stirring with a glass rod until dis- 
 solved. If much resinous matter be present it w T ill, 
 with entangled tannin, form glutinous lumps which 
 require some time and much stirring to break up. 
 Should but little resin be present, the solution will be 
 complete in a few minutes, when the liquid is to be 
 filtered through paper. The rapidity of filtering like- 
 wise varies with the amount of resin present : should 
 the filter become clogged, pour back the solution into 
 a glass, and change the paper. After being once or 
 twice filtered no further trouble will be given in the 
 same way. Pour into the bottles, and number 1, 2, 
 and 3 ; add half a drachm of alcohol to the ounce in 
 1 and 2, and one drachm to the ounce in 3. The use 
 of the alcohol is to preserve the tannin solution, and 
 to enable it to penetrate the collodion film more readily • 
 if the alcohol were added before filtering it would dis- 
 
37 
 
 solve much of the resin, which would be gradually 
 precipitated by the evaporation of the alcohol, and be 
 always clogging the filters. 
 
 Take two glass measures and place in each a small 
 gutta percha funnel containing a fresh filtering paper ; 
 pour the contents of No. 1 into one, and No. 2 
 into the other. Place three levelling stands side by 
 side ; lift the end of the first excited plate with a silver 
 hook (or, which will do as well, with a piece of stick 
 having a sharp-ended foot nearly at right angles made 
 by cutting off where a small branch comes out), and 
 when the end is out of the water take the plate up 
 with the fingers and place it on a pneumatic holder. 
 Wash under a tap for a few seconds to remove any 
 dust on the surface. Sensitive plates are often spoiled 
 in this operation by dirty water splashed from the sink. 
 To avoid this, tilt up under the tap a large plate of 
 glass, or a piece of board or slate, or a porcelain dish 
 upside down, at an angle of 30° to 45°. 
 
 Einse the film with a little distilled water to remove 
 the saline matters of the common water, and to prevent 
 their being mixed with the tannin solution; then, if the 
 plate be small, incline it so that the end at which the 
 collodion left the plate is uppermost, take hold of the 
 two corners of this end with the right hand covered 
 with a clean cloth, detach the holder and wipe the 
 back slightly with the left hand, then, shifting it under 
 a dry part of the cloth, take hold of the two lower 
 corners, and wipe again with the right hand. The 
 
38 
 
 draining and wiping will take about half a minute. 
 The object of wiping the back is not only to prevent 
 dilution of the tannin solution, but also to prevent 
 water coming into contact with the points of the level- 
 ling stand, and then carrying impurities into the tannin 
 solution. The object of covering the hands with the 
 cloth is to prevent water which has touched the fingers 
 from running on the sensitive surface, and also to avoid 
 making the film surface dry by the warmth of the hand, 
 as this would impede the flow of the tannin solution. 
 Take by the same corners as before with the right 
 hand ; these will now be surface dry, so the fingers 
 need not be covered by the cloth. Place on the left 
 hand levelling stand, and pour some of the solution 
 No. 1 on the right hand end of the plate, taking care 
 to leave the extreme corners 3 and 4 dry, that the 
 solution may not come in contact with the fingers. 
 
 The corners are here numbered the same as in the cut, at page 14, 
 and the gelatine and collodion are both supposed to have been 
 drained at 3. 
 
 Should the edges have become too dry to allow the 
 solution to flow on them, pour a little into the funnel. 
 
39 
 
 and while dripping carry along the dry parts with the 
 nose just clear of the surface. Bubbles are not easily 
 formed by the liquid, and if formed, break immediately. 
 Replace the funnel in the glass and hold in the left 
 hand ; take the plate by corners 3 and 4 with the right 
 hand, and tilt so as to drive all remaining moisture 
 before it into the funnel from corner 2. Then pour 
 on and off in the same manner some of solution No. 2; 
 pour on again and let it remain until the next two plates 
 have been treated in the same manner on the two other 
 stands. This way of working will give ample time for 
 the solution to penetrate the film, without causing any 
 loss of time. 
 
 Should the glasses be large, after rinsing with dis- 
 tilled water hold the plate vertically, with corner 2 
 downwards, and wipe the back round the holder 
 slightly; then take by corner 2 with the left hand, 
 covered with the cloth, the angle resting on the thumb, 
 the back supported by the fingers and the plate in a 
 nearly vertical position over the hand ; remove the 
 holder, and wipe again with the right hand. Corner 
 4 is to be kept dry, since by lifting it the solution is 
 poured off at corner 2, which is the most convenient 
 way of working. The wiping cloth should be of 
 cotton, and, if used for this purpose only, will remain 
 sufficiently clean for a long time. When three plates 
 have been covered with tannin solution, pour off the 
 first, when the surface will show oily lines from the 
 alcohol: these are of no consequence. Pour on and off 
 
40 
 
 once more. Attach the pneumatic holder, and, when 
 the solution has nearly ceased to drip, set the plate 
 upon filtering paper on the draining stand on comer 
 1 : by draining on this corner the solution is prevented 
 from leaving those edges of the film which are most 
 apt to repel it, and at the same time a somewhat thicker 
 coat of tannin is formed on that part of the plate where 
 the collodion film is thinnest. This state of things is 
 favourable to uniform intensity of development. 
 x Cover another plate with tannin in the same manner 
 on the levelling stand, then drain the next, and so on 
 till all are set up to dry. In using tannin solution 
 always pour from the plate into the filtering funnel, 
 which is to be kept in the glass measure, except when 
 pouring on, when it is to be held in the left hand over 
 the plate. This involves no trouble or delay, as the 
 liquid filters through quite as fast as it can be used, 
 and in this way dust is prevented from accumulating 
 in it. When a number of plates have been prepared 
 fill up No. 1 from No. 2, and No. 2 from No. 3 : by 
 this means dilution to any extent is avoided. 
 
 The glass measures and funnels never require 
 washing, and the filtering papers need only be changed 
 when they work too slowly. The solution may be 
 returned to the bottles after use, as it does not appear 
 to be at all injured when the plates are entirely free 
 from nitrate of silver; and this should always be the 
 case, since the presence of nitrate often causes stains, 
 and the sensitiveness of the plates, if dry, is not 
 
41 
 
 thereby increased — at any rate when the collodion 
 contains a sufficient amount of bromide. 
 
 The tannin solution sometimes becomes mouldy if 
 kept, particularly when the alcohol has been nearly 
 removed by evaporation from frequent use. A drop of 
 oil of cloves in each bottle entirely prevents this ten- 
 dency, and does not seem to produce any injurious 
 effect, unless undissolved globules of the oil are poured 
 upon the film. All chance of such globules may be 
 avoided by allowing the oil to remain at the bottom of 
 the bottle, which is never to be quite emptied, and by 
 taking care not to apply the solution to the sensitive sur- 
 face without previous filtration. Undissolved globules 
 of oil, if poured on with the solution, will adhere to the 
 film, and produce transparent spots of insensitiveness. 
 A quantity of strong solution of tannin, which became 
 very mouldy about four years ago, and to which oil of 
 cloves was then added, settled quite clear, and has 
 remained in the same state ever since, and, although 
 dark in colour, gives as good results as the freshly 
 prepared solution. 
 
 The plates, after being coated with tannin, should be 
 left to dry spontaneously at a moderate temperature, 
 rather than by artificial heat. In the case of the 
 gelatine process, and most other dry processes in which 
 the nitrate of silver is entirely removed, drying strongly 
 by heat is favourable to sensitiveness ; but plates pre- 
 pared with tannin appear to be exceptional, their sensi- 
 tiveness being increased by drying up to a certain 
 
42 
 
 point, and beyond that being diminished again. The 
 amount of dryness which appears to be- most favourable 
 is about that which the film will attain spontaneously 
 in the ordinary state of the air, It is evident from the 
 above that, however dried, the film should be uniformly 
 dry when exposed. Another objection to drying at a 
 high temperature is, that it renders the film more 
 liable to loosen from the glass when moistened for de- 
 velopment. On the other hand, if the film be exposed 
 when in too moist a state, the definition of the image 
 will be found to be injured. Great care should be taken 
 not to expose the plates to light whilst drying, as- 
 even the light from a dull fire will soon injure them. 
 Access of dust to the film whilst moist should also be 
 carefully guarded against ; but, when the plates are dry,, 
 this point is of little consequence, as the surface will 
 bear wiping. The plates when dry may be kept in the 
 way recommended for the gelatinized glasses ; but they 
 must, of course, be well protected from light as well as 
 from damp. The quicklime will scarcely be required, 
 as the surface, when coated with tannin, does not, 
 if moderately dry, appear to be liable to become 
 mouldy. If the lime be used, the plates should be 
 placed in the slides a few hours before exposure that 
 they may absorb a very small degree of moisture from 
 the air. The writer has not found the plates at all 
 deteriorated by keeping ; but he has not tested them 
 beyond a month before exposure, and six weeks after 
 exposure, but before development. Whether the gela- 
 
43 
 
 tine will diminish the keeping quality of the plates, 
 especially in hot weather, by keeping a trace of nitrate 
 of silver in combination, must be determined by 
 experience. 
 
 When the film is dry, the surface should present 
 a bright and highly- polished appearance. If the collo- 
 dion has been made from good pyroxyline, any dullness 
 seen by reflected light is always the result of some 
 kind of mismanagement, and is most commonly pro- 
 duced in one of the following ways : — First by adhesion 
 of insoluble salts of silver, from the plates having been 
 placed in hard water, or salt and water, before the 
 nitrate was sufficiently removed by distilled water; 
 secondly, by the film having been too much dried 
 before immersion in the nitrate bath ; and thirdly^ 
 from the use of over-iodized collodion. In the first 
 case the precipitated matter will appear in smears 
 following the direction in which the plate entered the 
 hard water, or in which the water first flowed over it. 
 In the second case, the deposit will probably be 
 confined to the neighbourhood of the two edges which 
 were upwards when the collodion was poured off, which 
 edges will look blue and transparent. In the third 
 case, the loose iodide will be distributed more uniformly 
 over the plate, without the transparent edges at the 
 upper end. In the first case, if the precipitated 
 matter is of small amount, it may be entirely removed, 
 and the plate made practically as good as if no deposit 
 had been formed on it, by attaching the glass to the 
 
44 
 
 holder, and rubbing the surface with a tuft of clean 
 dry cotton wool. This should have a handle formed 
 by binding round a part of the wool with string, the 
 end of which should form a loop, to hang on a nail 
 in the edge of a shelf or other convenient place. If 
 kept for this purpose only it may be used for a great 
 length of time. In the second and third cases, the 
 plate will be improved by removing the loose iodide in 
 the same manner ; and in the second case, the picture 
 will be good on that portion of the film which retains 
 its opacity, and is not rendered more transparent by 
 the loss of iodide of silver. In the third case, a good 
 result canr.ot be expected, especially when the amount 
 of loose iodide is large, and has marked the film by 
 bursting out irregularly. 
 
 In all cases it will be well to brush the surface of 
 the excited plate with the cotton wool before placing it 
 in the slide, to remove any particles of dust which may 
 be present. If a new' and horny collodion was used 
 pretty hard rubbing will cause no injury, especially 
 when the solution of tannin was somewhat concen- 
 trated. 
 
CHAPTER V. 
 
 EXPOSURE, DEVELOPMENT, AND FIXING. 
 
 Up to this point there is no risk of failure if the fore* 
 going directions are carried out with the ordinary 
 attention to cleanliness necessary in all processes ; and 
 except in those matters on which especial stress has 
 been laid, great latitude of treatment is admissible. 
 In the exposure and development, however, great care 
 and experience are required to ensure the best results. 
 With regard to the time of exposure, much difference 
 will be found in the sensitiveness of the plates, accord- 
 ing to the mode of preparation. The principal causes 
 of insensitiveness have been already given : they are 
 the use of a simply iodized collodion, or of an old 
 sample, or of a bath much more acid than is required 
 to keep the pictures bright. Should two, or all of 
 these unfavourable conditions be combined, the insensi- 
 tiveness will be very great. The use of an alkaline, 
 neutral, or insufficiently acid bath, with a nearly or 
 quite colourless collodion, will also produce insensi- 
 tiveness to half-tones as well as fogging. The writer 
 has prepared plates by the method given in the pre- 
 ceding pages more sensitive than those he can pro- 
 duce by any other dry process with which he is 
 acquainted, consistently with obtaining vigour and 
 
46 
 
 brightness, and he believes that this process will be 
 found to give brilliant and vigorous results, combined 
 with softness and good half-tones, with greater 
 facility and certainty than any other process when 
 the subject is feebly lighted. 
 
 The observance of a few simple precautions will 
 ensure good results, whatever be the light or the 
 nature of the subject ; but the same qualities which 
 are favourable in the case of a badly-lighted subject 
 make more care necessary to produce the very best 
 results when the subject is well lighted and contains 
 great contrast, such as dark foliage at a short dis- 
 tance and sky.* 
 
 Could we always ensure the exact accuracy of the time 
 of exposure it would be easy to give a formula for a 
 developing mixture which would always succeed with 
 any given kind of subject. In the case of dry plates this 
 is impossible, as the time of exposure must always be 
 more or less uncertain, unless, as in the wet process, 
 each plate be immediately developed, and so the proper 
 time of exposure be ascertained for the next. In the 
 ordinary way of working all that can be done is to give 
 * The writer has not yet found time to investigate thoroughly 
 the conditions and treatment which give the very best kind of 
 pictures with the last-mentioned kind of subjects, but believes 
 that they can be obtained by this process of as good a quality 
 as by any other, judging by the specimens which he has already 
 produced, and by the great power we have of regulating the 
 quality of the negatives by the use of different collodions and 
 solutions of tannin varying in strength, and by the time of ex- 
 posure and the nature of the developer. 
 
47 
 
 general rules, and to indicate the effects of different 
 modes of treatment, which, to produce the best results, 
 must be slightly varied in almost every case. The fol- 
 lowing formulae will be found^ to produce developing 
 fluids suitable for this or any other process.* 
 
 (1.) Pyrogallic acid........ 96 grains. 
 
 Absolute alcohol 1 ounce. 
 
 Pour the alcohol, which should he anhydrous, or at 
 all events as strong as can be obtained, into a two- 
 ounce bottle with a good flat rim. If the bottle be 
 full it will be difficult to pour without waste. Add 
 the pyrogallic acid, which will dissolve immediately ; 
 shake up to equalise the strength of the solution, and 
 add two or three drops of ether (this is not neces- 
 sary). The solution will scarcely alter in colour in 
 six months, and its use is much more convenient than 
 constant weighing out. Treated in this way the pyro- 
 gallic acid will retain its full strength, which is not 
 the case when it is dissolved in water, or even in 
 strong acetic acid. Five minims of the solution con- 
 tain one grain of pyrogallic. If it is to be used for 
 wet collodion, measure the required quantity, dilute 
 to the proper strength, and add the required quantity 
 of acid. 
 
 * Albumen and collodio-albumen plates will require in (2) 
 Aie substitution of acetic for citric acid, which, being a solvent 
 of albumen, is apt to cause blisters. The acetic acid must be 
 in large enough proportion to prevent turbidity in the developer, 
 and the solution should be used direct from the bottle, to avoid 
 loss of acid by evaporation. 
 
48 
 
 (2.) Nitrate of silver...., 10 grains. 
 
 Citric acid 10 to 60 ,, 
 
 according to the strength of the tannin solution, heat 
 of the weather, nature of the subject, &e. 
 
 Distilled water 1 ounce. 
 
 The advantages gained by using the acid in the 
 silver instead of in the pyrogallic solution are very 
 great. When the plate is rather under-exposed, and 
 only a little silver is required with strong pyrogallic, 
 the half-tones come out much better than when, as in 
 the common method, a large quantity of acid is pre- 
 sent. On the other hand, when the plate is over-ex- 
 posed, a strong solution of acidified silver can be used 
 with a small quantity of pyrogallic without causing 
 turbidity in the liquid, or throwing down any loose 
 irregular deposit likely to injure the details of the 
 picture. This acid solution of silver will be found ex- ^ 
 ceedingly useful to add to the developer in the wet 
 process, when, from the nature of the collodion or the 
 feebleness of the light, the image comes out perfect in 
 detail but of insufficient intensity ; or it may be used 
 with pyrogallic to intensify negatives developed with 
 iron. If, as is the usual practice, plain nitrate solu- 
 tion he added to the developer — unless the amount of 
 acid has been unnecessarily large for the first stage of 
 the development — the least addition of the nitrate 
 causes immediate turbidity, and a muddy deposit falls 
 at every part of the film : not only so, but the silver 
 itself is thrown down in a coarse granular state, giving 
 
49 
 
 less density and destroying all delicacy of detail. No 
 such effects follow the addition of nitrate of silver 
 accompanied by a sufficient proportion of acid. 
 
 The development of plates prepared with tannin may 
 be made at least as rapid as in the wet process by 
 using a strong developer at once ; but this mode of 
 proceeding is not advisable in the case of negatives, as 
 it determines the character of the picture so rapidly 
 that if much over or under exposed it will be entirely 
 spoiled. In all cases this treatment prevents the 
 attainment of the best possible results, except by 
 accident. The following method of development will 
 be found preferable, and, if conducted with care and 
 skill, will] allow of great latitude in the time of ex- 
 posure : — 
 
 For a stereoscopic plate, allow one drop of (1) to fall 
 into a glass measure, holding the stopper against the 
 lip to prevent the liquid from creeping down the out- 
 side of the bottle ; pour two or three drachms of dis- 
 tilled water into the same measure ; then filter through 
 paper in a small gutta-percha funnel into the glass 
 which is to be used in developing. Pyrogallic solution 
 should always be filtered, especially when used soon 
 after being made or diluted ; otherwise any particles 
 of insoluble matter in the solution, however small, if of 
 a porous nature, will cause “ comets ” on the negative 
 from being more strongly imbued with pyrogallic acid 
 than the fluid which surrounds them. 
 
 Pour a few drachms of (2) into another filter of the 
 
 D 
 
50 ' 
 
 same kind, which, with a glass measure, should be- 
 kept ready for the purpose. The above-mentioned 
 funnels and glass measures, excepting the one used 
 in developing, never need be washed nor the papers 
 changed until they filter too slowly. These filterings 
 may be conveniently managed as follows: — Cut a 
 square piece of thin board, such as a piece of a cigar 
 box, a little larger than the top of the glass measure : 
 make a hole in the middle, of such size that the nose of 
 the funnel will go through about an inch, or more, 
 according to the size of the funnel, and push in with 
 sufficient force to make the wood adhere firmly. The 
 funnel can now be lifted with its support from one 
 measure to. another; and, should it be required to move 
 the glass while filtering, a finger placed on the wood will 
 keep the funnel in its place. When silver is to be 
 added to the developer lift the funnel, pour a little of 
 the solution into it, and hold over the developing glass, 
 counting the drops to regulate the quantity added. 
 The fluid having been before filtered through, will 
 ensure its being clean. 
 
 A still easier way of adding the silver is to place the 
 funnel in the retort holder, the nose being an inch or 
 so above the top of the glass measure. When any of 
 the solution is required, with the right hand pour a 
 little of what has been filtered into the funnel, and 
 hold the developing glass under with the left till the 
 required quantity has dropped, when the other glass 
 takes its place again. This is as easy a way as any of 
 
51 
 
 adding small quantities of silver ; but, if preferred, the 
 solution may be dropped direct from the bottle. In 
 the absence of a retort stand, a piece of thin board 
 having a hole to receive the funnel will do as well, if 
 laid on a box of the right height, with some heavy 
 object on it to keep it in its place. 
 
 Whilst the solutions are filtering, take the plate 
 which is to be developed and moisten it in this man- 
 ner: — Lay it on a levelling stand and pour distilled 
 water along the nearest edge of the glass ; spread care- 
 fully over the surface with a perfectly clean glass rod 
 (bent at one end, and a little longer than the width of 
 the glass), taking care not to touch the film except at 
 the edges, and not to let the end of the rod project 
 beyond the edge of the plate, as this would lead the 
 water over the side : should this happen, remove the 
 water from the back of the plate with blotting-paper. 
 The extreme corner or corners which are to be handled 
 should be left dry : this will keep the fingers and also 
 the negative clean. Let the water remain until the 
 film is thoroughly penetrated, which is known by its 
 being equally whitened. This will take from two to 
 four minutes : the more quickly the water has been 
 spread the less time will it require to remain. The 
 water should not be left very long on the plate, as, 
 when gelatine of insufficient strength has been used to 
 hold a thick collodion, an hour’s soaking in water may 
 loosen the film, even although the developer would 
 have no such effect. 
 
53 
 
 Should it be preferred, 'the plate may be moistened 
 by dipping it in a bath of distilled or common water. 
 In this case, after a few seconds’ immersion, lift it out 
 of the water and allow it to drain on the dipper until 
 the upper corners are nearly or quite surface dry, 
 otherwise water which has touched the fingers may 
 flow on the sensitive surface, and produce a mark of 
 non-development ; or, to be quite safe, the corners to 
 be handled may be touched with negative varnish be- 
 fore the plate is dipped. After moistening by dipping, 
 wipe the back of the glass to prevent water flowing from 
 the points of the stand into the developing glass. 
 
 When the plate is moistened, mix by stirring one 
 drop of the silver solution with the dilute pyrogallic ; 
 pour off the water, but not too closely, or the edges may 
 become surface dry. The tannin remaining does no 
 injury. Pour the mixture on the right-hand end of 
 the plate, and incline the latter so as to drive off all 
 the moisture before the developer into the glass. The 
 same method of pouring must be repeated after every 
 addition of pyrogallic or silver, to avoid producing 
 unequal intensity. Pour on again at the other end of 
 the plate, and repeat the pouring on and off several 
 times, watching as the image appears. If any part 
 come out more slowly than the rest from imperfect 
 mixture of the developer with the water previously on 
 the plate, pour afresh over that place two or three 
 times, that the whole may start nearly simultaneously. 
 If nothing appear in three or four minutes, add more 
 
53 
 
 pyrogallic. This should be filtered by dropping on the 
 filter and washing through with a little water ; or it 
 may be measured in a minim glass and poured on the 
 filter, the measure being then rinsed with a little water, 
 which is afterwards to be also poured on the filter. 
 View the image carefully by transmitted light every 
 time the developer is poured off : on looking through 
 it the proper treatment will soon be seen , but it is of 
 great importance not to add pyrogallic too fast, as, 
 should the plate be over-exposed, such a proceeding 
 will establish the character of the picture too quickly to 
 admit of contro 1 . Should there appear too much con- 
 trast and deficiency of half-tone from under-exposure, 
 add the slightly diluted and filtered pyrogallic drop by 
 drop, watching the effect ; if, on the other hand, the 
 image appear quickly and is full of detail, but looks 
 flat from want of contrast, add more acid silver in the 
 same way. For a third case the film, from great over- 
 exposure, may begin immediately to redden all over, 
 showing the image but faintly : if so, pour away the 
 developer and replace with a few drops of acid silver 
 diluted with water. In such a case, the small trace of 
 pyrogallic left on the film will be quite sufficient to 
 complete the development, when silver enough has been 
 added. If the image show about the right amount of 
 contrast, and the half-tones begin to appear at the 
 proper time, the pyrogallic and silver solutions may be 
 added together ; and if at any stage of the development 
 too much of either solution has been inadvertently 
 
54 
 
 used, the developer must be instantly poured away 
 and replaced by a fresh mixture made in the correct 
 proportions. 
 
 The developer first used will sometimes become tur- 
 bid, especially when strong pyrogallic has been applied 
 with very little silver, previously to the appearance of 
 the image. When the plate has been under-exposed, 
 however, the pyrogallic should not be added too late, or 
 the character of the picture will have become esta- 
 blished, and the half-tones will not admit of develop- 
 ment. Experience is the only guide as to the right 
 time to add pyrogallic in any particular case. Should 
 the slightest turbidity appear, reject the old solution 
 as soon as the image is sufficiently out to show r what 
 kind of developer is required ; a fresh quantity mixed 
 in the proper proportions will be pretty sure to go right 
 without the precaution of waisliing the plate and deve- 
 loping glass. The fluid will become more and more 
 dark coloured with each fresh addition of silver, pro- 
 bably until it is as dark as port wdne, but it ought to 
 remain all the while bright and clear. 
 
 This mode of developing admits of either or both 
 solutions being dropped into the empty glass while 
 the developer is on the plate, and the latter may then 
 be poured in without any bad effect. Should several 
 plates have been exposed similarly, the subjects being 
 also similar, three plates, especially if small, may be 
 developed at the same time ; but, in case they should 
 require different treatment, two extra clean measures 
 
55 
 
 should be ready, so that each plate may, if necessary, 
 have a separate developer. The method of develop- 
 ment above described is purposely made slow at first ; 
 but as soon as the kind of developer required is indi- 
 cated, it may he finished more rapidly, by strengthening 
 with such proportions of the solutions as experience 
 shows to he needed in any particular case.* 
 
 The only failure which the writer at first expe- 
 rienced with tannin was that o f blurring, or encroach- 
 ment of the sky or highest lights on the more trans- 
 parent parts of the negative as a halo of red stain. 
 This, when it once appears, prevents all half-tone 
 from coming out in the parts affected, farther pushing 
 of the development only deepening the stain. This 
 cause of failure depends on the development, and is 
 scarcely at all affected by the state of the bath or col- 
 lodion. After every thing but the right one had been 
 tried, it was found that this annoyance could be pre- 
 vented with certainty, even where there had been 
 great over-action of light, by very simple means — that 
 of using more acid in the silver developing solution. 
 No one proportion can be given as suitable in all 
 cases ; but the following rule will be found to be prac- 
 tically sufficient: — The minimum quantity of citric 
 acid used with each grain of nitrate of silver should 
 be about one grain of acid for every ten grains of 
 
 * When the proportion of silver is very small, the developer 
 may he left at rest on the plate for a long time ; hut, when much 
 silver is present, this treatment will cause mottled markings to 
 appear, if such exist in the texture of the collodion film. 
 
56 
 
 tannin contained in one ounce of its solution. It -will 
 scarcely be found advisable to use so small a propor- 
 tion as this for landscapes containing sky, or other 
 kinds of subjects containing great contrast of light and 
 shade, or for any subject in very hot weather, as in these 
 cases more acid is necessary than would otherwise be 
 required. The best guide is the appearance of the 
 finished negative. The slightest trace of the above- 
 described blurring is a proof that not nearly enough 
 acid has been used.* Again, on looking along the 
 surface w T hen dry, at a small angle towards the light, 
 the whole should be as bright as glass; and dulness 
 on the transparent parts least affected by light, if at 
 all marked, is another indication of the same fault in 
 the developer, except in the case of an under-exposed 
 negative much pushed in development with strong 
 pyrogallic and little silver: in this case we may 
 expect a slight deposit, even though a proportion of 
 acid sufficient for properly-exposed plates may have 
 been used. Under these circumstances, a more highly 
 acid solution than would otherwise be required may 
 be used for the first stage of development, or, if it be 
 thought desirable, a few drops of a ten-grain solution 
 of citric acid, or a little acetic acid, may be added with 
 the first drop of acid silver. When the half-tones 
 
 * Unless gallic and pyrogallic acids have both been used on 
 the same plate. This treatment will always produce the fault 
 in question when the subject presents much contrast and a 
 strong solution of tannin has been used, though the silver 
 solution may be acid enough for use with pyrogallic alone. 
 
are out, no more acid will be required to intensify 
 than in ordinary cases. It will be found convenient 
 to keep ready several bottles containing silver solution 
 of different degrees of acidity, from one and a-half or 
 two grains to four or more grains of citric acid to the 
 grain of silver. 
 
 Each bottle should have its own filter and glass 
 measure. The acid silver solution appears to keep 
 well : a horny, semi-transparent substance is some- 
 times formed in the liquid, but the action which pro- 
 duces this effect does not seem to alter perceptibly 
 the quality of the solution. In determining the pro- 
 portion of acid to be used, it should be borne in mind 
 that too much is far less injurious than too little. 
 Four grains of acid to one of nitrate will give excel- 
 lent results on plates prepared with tannin solution 
 fifteen grains to the ounce, although this quantity is 
 much greater than is usually required. No fear need 
 be entertained that a large proportion of acid will 
 prevent the half-tones coming out ; for, if the propor- 
 tion of silver in the developer be kept low till the half- 
 tones appear, much less acid is present at this stage, 
 even with a very acid solution, than in the ordinary 
 method. The only injurious effect of an unneces- 
 sarily large proportion of acid will be a slightly colder 
 tone of colour, which is of no consequence in a nega- 
 tive. 
 
 The power of regulating the result by the above 
 mode of developing is so great that, when assisted by 
 
58 
 
 the peculiar properties of tannin, it enables us to pro- 
 duce a good picture with almost any collodion. 
 
 If the right exposure, within the necessary limits, 
 has been given, and the development properly ma- 
 naged, the finished negative will resemble a good one 
 produced by the wet collodion process ; but the defini- 
 tion, as*in the albumen process, maybe expected to 
 be more perfect from the impression being taken 
 on a smooth and polished surface instead of on an 
 expanded and spongy substance with a somewhat 
 irregular surface, which is afterwards contracted and 
 rendered smooth by drying. The greater part of the 
 film will appear by reflected light of a yellowish 
 brown colour — except the sky and high lights, which 
 will be dark, and the deepest shadows, which will be 
 transparent, and will appear black when a dark object 
 is held behind the plate. In ordinary subjects, how- 
 ever, this transparent appearance should be confined 
 to a few touches. On looking through the plate the 
 picture will be bright and vigorous, but soft and full 
 of half-tone; and should the sky or high lights be 
 solarized, they will be of a deep purplish red, which 
 stops light in printing much better than the pale 
 solarization often produced in other processes. The 
 parts which appear quite black and opaque when 
 examined by diffused light, will be found to be really 
 translucent when placed close to the flame of a candle 
 or lamp. The blackest parts, when looked through in 
 this way, will resemble very dark, transparent stains 
 
59 
 
 in the glass, without a trace of granulation, and 
 showing all the detail. The kind of negative described 
 above can. only be produced by the wet process when 
 the collodion and bath are in good order; but plates 
 prepared with tannin, being much less dependent on 
 the state of the collodion and bath, will give results of 
 the above kind with much greater certainty. * 
 
 No other process can be less liable to fogging or 
 stains than this one, the former never appearing unless 
 the bath be alkaline or insufficiently acid, or unless 
 the light has got access to the plate ; while the latter, 
 if the nitrate be entirely removed, can scarcely be pro- 
 duced by any treatment short of splashing impurities 
 on the film. 
 
 It is of great importance to have the developing 
 glass and glass rod used to guide the flow of the deve- 
 loper from the measure to the plate thoroughly clean 
 before commencing. For this purpose, make a solution 
 of about twenty grains of any soluble iodide to the 
 ounce of water, with as much iodine as will dissolve. 
 The exact strength is of no consequence, but the solu- 
 tion should be of a deep port-wine colour. Keep about 
 a pint of this in a bottle ; and, after developing, fill the 
 glass containing the rod with the liquid, pour into 
 another glass of the same size, and immerse the edge 
 or lip to clean it outside and inside, and then return the 
 
 * The details in the shadows of a tannin negative should all 
 he faintly visible, even if, from under-exposure, they cannot be 
 made intense enough to print. 
 
60 
 
 solution to the bottle. The glasses may be now left 
 till required for use, when they are to be rinsed with 
 water, rubbing with the finger. The entire removal of 
 any deposit which may be present is of no consequence, 
 as the silver is now converted into iodide in the inert 
 state, and exercises no greater effect than is produced 
 by the film itself in the parts unaffected by light. 
 This liquid is safer to use and more efficacious than 
 nitric acid or cyanide, since when the latter are used 
 any deposit not entirely removed will still affect the 
 developer. The superior energy and penetration of the 
 iodine solution may be proved by dipping the nose of a 
 gutta-percha funnel, which from long use with nitrate 
 solution has become stained with reduced silver, into 
 nitric acid or cyanide solution. No very perceptible 
 effect will be immediately produced ; but, if it be dipped 
 into the iodine solution, the deep stains will be quickly 
 changed to a primrose colour. Stained gutta-percha 
 trays may with this solution be so effectually purified 
 in a few minutes, that paper negatives may be developed 
 in them with the same cleanliness as in a new glass 
 dish. Care must be taken not to allow the iodine and 
 iodide to touch a sensitive plate. A trace of the fluid 
 will do no harm in the glass which receives the mixed 
 developer ; but the glass measure and rod should, after 
 cleaning with iodine, be well rinsed before being used 
 to apply water to a plate preparatory to development. 
 The cleaning solution will stain the skin when undi- 
 luted ; but it may, nevertheless, be used to remove 
 
61 
 
 reduced silver from the fingers, as its application 
 greatly facilitates the subsequent action of cyanide, 
 which will then quickly remove both silver and iodine. 
 A little iodide and iodine should be added to the 
 solution when its paler colour shows that it has been 
 weakened by long use. 
 
 Unless a very thin solution of gelatine has been used 
 with a thick collodion, the film will show no tendency 
 whatever to become loose during development. Should 
 this fault appear, the negative will not be worth finish 
 ing, and in future stronger gelatine or thinner collo- 
 dion must be used. There need be no risk of failure 
 from this cause. 
 
 When the development is complete, wash till all oily 
 appearance is removed ; for, if the plates be placed in 
 hyposulphite with oily markings upon them, these will 
 be visible to some extent afterwards, in this or any 
 other collodion process. The film, being amalgamated 
 beneath with leather, is so strong that it cannot be 
 injured by a heavy stream of water ; even if purposely 
 torn, the water will not penetrate between the film and 
 the glass. Cyanide must not be used for fixing, as 
 any alkaline liquid will loosen the film. The strength 
 of the hyposulphite is of little consequence ; but it 
 need not be strong, as the fixing is more easy and 
 rapid than in the case of other dry processes. Strong 
 hyposulphite will not, however, produce much effect 
 upon the intensity of the negative, if the collodion be 
 
’62 
 
 of such a nature as to keep the image in the film and 
 not on the surface. 
 
 In this, as in most other dry processes, the film will 
 sometimes become slightly loosened in the final wash- 
 ing, especially wdien the gelatine has been too weak 
 or the collodion old and powdery : a new collodion, 
 giving a horny film, adheres more strongly when used 
 on gelatine. Slight loosening at this stage seldom 
 affects the negative when dry ; but it may generally be 
 prevented by adding a little tannin solution to the 
 hyposulphite. This addition causes turbidity, and 
 afterwards a red colour ; but does not destroy the 
 solvent power of the solution, nor does it appear to 
 produce any injurious effect. Should the above-men- 
 tioned loosening occur through any mismanagement, it 
 will be better, in the case of a good negative, to finish the 
 washing by covering the plate with distilled water for 
 some time on a levelling stand, to remove as far as 
 possible any soluble matter under the film, otherwise 
 such matter may show slightly when dry. After being 
 washed, the plates are to be set up to dry on blotting- 
 paper. 
 
 If any loose deposit appear on the surface of the 
 film it may be removed, when quite dry, with a brush 
 made of eider down, which is much less liable to injure 
 the surface than cotton wool or the softest hair brush. 
 Eider down is often to be found in coats, quilts, &c., 
 which are lined or filled with it. To make a brush 
 pick out the largest pieces singly, find in each the 
 
63 
 
 small quill by which it was attached to the skin, collect 
 five or six, and form into a small brush by bringing 
 the quills together and twisting this end round be- 
 tween the finger and thumb with a little solution of 
 caoutchouc in turpentine, or other cement. Make a 
 sufficient number of these small brushes to form a 
 round ball of down about the size of a walnut. Bring 
 the cemented ends together and insert in a fowl’s quill, 
 which has been cut off near the end and split in two or 
 three places ; then bind the quill round firmly with 
 waxed thread. This brush ought not to be often 
 required to remove loose deposit, but is always useful 
 to clear off dust before varnishing, and if applied lightly 
 will do no injury. 
 
 The film, if on gelatine, will never crack or split off 
 on drying, nor has the writer seen an instance of its 
 doing so when gelatine has not been used, except 
 when a very weak solution of tannin was employed 
 in the vain hope of preventing the loosening of the 
 film. If the collodion be unsuitable for this purpose, 
 it will become wrinkled almost as much with three 
 grains as if thirty grains to the ounce had been used, 
 and in the former case the development is very feeble. 
 Dispensing with the gelatine does not seem at all 
 advisable, when, by its use, absolute security from all 
 mechanical difficulty can be obtained at so little 
 trouble. Before varnishing, dry the plates well by 
 artificial heat, and varnish when sufficiently cooled. 
 In most cases the cracking of negatives is caused by 
 
64 
 
 their being varnished while damp. After varnishing, 
 keep the plates at a higher temperature than the sun 
 can ever cause, until the varnish ceases to be soft and 
 sticky at that heat, to prevent their adhering to the 
 paper in printing. 
 
CHAPTER VI. 
 
 ON PRINTING TRANSPARENCIES. 
 
 Dry plates prepared with tannin give very good re- 
 sults when used for printing transparent positives by 
 superposition. The action of the tannin and pyro- 
 gallic acid tends to produce a deep red colour, and the 
 citric acid to give a blue tone ; hence, by varying the 
 proportion of the latter, we can produce at will a great 
 variety of tints between a nearly pure neutral and 
 various shades of purple. 
 
 Gallic acid, if used for developing, gives a green 
 colour, so that if a brown tone be desired it can be 
 produced by using first gallic acid and then pyro- 
 gallic : this, however, can only be done successfully 
 when the tannin has been used in weak solution, not 
 more than ten grains to the ounce, and when the 
 negative is of rather low intensity ; otherwise blurring 
 will be produced round the dark parts of the positive 
 (see note, page 56). 
 
 Plates prepared as described in the preceding pages 
 will be found too sensitive to use in this way with 
 direct daylight of ordinary power, one second’s ex- 
 posure, inside a north window, just before sunset, being 
 quite sufficient if the negative be of that intensity 
 which gives the best .results. Plates so prepared may 
 
 E 
 
08 
 
 however be used for printing by ordinary daylight, if 
 exposed horizontally on a table in a room which has a 
 north aspect, care being taken to intercept the direct 
 light from the window before uncovering the negative. 
 Old collodion answers better than new in a strong 
 light, from its giving a less sensitive film ; but it is 
 more liable to injury from pressure against the nega- 
 tive, being comparatively soft and porous. 
 
 Thirty grains of tannin to the ounce, on a horny 
 collodion, makes a very hard film, little liable to injury 
 in printing, and gives very vigorous and richly -toned 
 positives. About three grains of citric acid must, in 
 this case, be used for development with each grain of 
 silver, or the tone will be too red, and there will be 
 danger of blurring and loose deposit, especially if the 
 negative be intense. Should it be found difficult to 
 use acid enough to prevent loose deposit without 
 giving too cold a tone to the picture, acetic acid may 
 be partially substituted for citric acid ; but this diffi- 
 culty is not likely to occur. Acetic acid may be used 
 iu the same way to produce a slight difference of 
 colour. 
 
 It will be found difficult to obtain good results with 
 certainty when daylight is used for printing, on 
 account of the variation of light. By developing in the 
 manner recommended for negatives, we can indeed 
 correct the effects of under or over-exposure within 
 certain limits ; but it is scarcely worth while to take 
 this trouble, especially as the shade of colour will vary 
 
67 
 
 with the kind of developer required to suit the ex- 
 posure. An over-exposed picture, for instance, which 
 requires to be developed with acid silver, and only a 
 small trace of pyrogallic, though good in other respects, 
 w'ould be of too cold and inky a tone. The best way 
 of working is to find, by experiment, a time of expo- 
 sure and proportion of developing fluids which pro- 
 duce, in the ease of each negative, the intensity and 
 colour desired, and then to use the developer of full 
 strength at once : by this means the development will 
 be made very rapid, and, if an uniform artificial light 
 be used at a measured distance, the best results will 
 be obtained with great certainty. Plates prepared as 
 described for negatives are, from their sensitiveness, 
 well adapted for printing by artificial light. 
 
 Tannin plates need no toning with gold, and not 
 only have the advantage of producing very beautiful 
 colours, but they admit of use with much more intense 
 negatives than would be suitable in the case of other 
 dry processes. A negative so intense as to give solari- 
 zation, with hard, wiry edges in the general way, will, 
 if used to print on tannin plates, produce soft pictures, 
 in which the only defect will be too red a tone in the 
 dark parts. This redness may be neutralized by more 
 acid in the developer, and the result will then be good, 
 except that the lighter parts will be somewhat cold in 
 tint. Judicious management of the exposure and 
 development will so control and balance this difference 
 of colour, that the effect will not be unpleasant in 
 
68 
 
 many subjects. To obtain absolute uniformity of 
 colour in the light and dark parts it will, however, be 
 advisable to use a negative of rather low intensity. 
 
 Negatives produced by the tannin process are, when 
 a collodion giving a strong film has been used, better 
 adapted for printing transparencies than those obtained 
 by any other dry collodion process, from being much 
 less liable to injury : they are also somewhat more 
 durable than wet collodion negatives, the coagulated 
 gelatine giving greater strength to the film below, and 
 better adhesion to the glass ; nevertheless, the surface 
 is not so hard that it can be used unprotected, like 
 albumen, and it therefore requires to be defended by 
 Varnish of some kind. 
 
CHAPTER VII. 
 
 REMARKS ON DRY PROCESSES. 
 
 A few remarks may here be made on the merits and 
 demerits of some of the best known dry processes. 
 The gelatine and metagelatine processes are simple, 
 develop with great cleanness, and can be made to give 
 good results. The great objection to them is their 
 strong tendency to blistering ; this renders it difficult 
 to prepare a collodion which will adhere sufficiently to 
 the glass, will produce an uniform film free from 
 mottled markings, and, at the same time, will give a 
 tolerable degree of sensitiveness. Different propor- 
 tions of ether and alcohol in the same collodion will 
 produce blistering or mottling, and the latitude in this 
 respect is so small that the same plate, if large, will 
 sometimes produce blisters at the upper part from too 
 much ether, and mottling at the lower corner from too 
 little. Even if, by a method to be presently described, 
 sufficient adhesion be secured to admit of the use of a 
 sensitive collodion, the development is usually slow, 
 and less range of tone is obtained than when the film 
 is coated with tannin. 
 
 The collodio -albumen process will produce excellent 
 results, with some degree of certainty ; but involves 
 great trouble, and is liable to the same objections 
 
70 
 
 as the gelatine process, though in a far less degree. 
 Sensitiveness is much less affected by the use of a 
 powdery collodion, and mottling of the film is not so 
 apt to show in the picture, especially if thick albumen 
 be used. Even in this process, however, a little too 
 much ether added to the collodion, after evaporation 
 by use, to prevent mottling, will sometimes cause 
 blisters to appear when everything worked well pre- 
 viously. One of the greatest objections to the process 
 is the difficulty of producing anything like a perfect 
 coating of albumen, from the formation of gelatinous 
 lumps and filaments in the liquid after filtration. The 
 difficulty of filtering the albumen, if thick, and its 
 tendency to form small bubbles, which adhere to the 
 film with great tenacity, are also hindrances. These 
 difficulties can be overcome by good manipulation ; 
 but the coating with albumen alone will, if carefully 
 performed, take more time than the use of both 
 gelatine and tannin in the tannin process. 
 
 Another objection to the collodio-albumen process is 
 the liability of the surface of the albumen to contract 
 stains from the nitrate bath. These may generally be 
 avoided by using nothing in the albumen which will 
 render it more absorbent, and drying the film strongly 
 by artificial heat before the second excitement, although 
 the development is thereby rendered slow and trouble- 
 some. If sugar, treacle, or nitrate of magnesia be 
 used with the albumen the development is facilitated ; 
 but the liability to stains is, from the porous nature of 
 
71 
 
 the film, so greatly increased that in some states of the 
 bath they can hardly he avoided. When any dry 
 porous surface is immersed in the nitrate bath there 
 must always be a chance of its contracting stains, and 
 the liability will vary with the degree of porosity and 
 the state of the bath. The tannin process gives better 
 results with badly lighted subjects than the collodio- 
 albumen and has other obvious advantages ; never- 
 theless, it must be allowed that pictures produced by 
 the collodio-albumen, in skilful hands, are of first-rate 
 excellence, and time and experience only can decide 
 between the two methods. 
 
 Fothergill’s process is much simpler and less trouble- 
 some than the collodio-albumen, and is free from some 
 of its faults. The difficulty of forming a good coat of 
 albumen and of avoiding bubbles and filaments is got 
 rid of, and a newer collodion may be used without pro- 
 ducing blisters. On the other hand this process has 
 defects of its own, one of which is an increased liability 
 to stains. In the ordinary way of working Fothergill’s 
 process it is difficult to obtain great sensitiveness 
 without approaching the limit at which these stains 
 begin to show, from the contact of nitrate of silver and 
 albumen upon the film. The process is also dependent 
 to a very great degree on the quality of the collodion 
 used, which, if unsuitable, renders the development 
 very slow and feeble. Not only do the sky and high 
 lights become pale from solarization before the dark 
 parts of the subject are sufficiently exposed, but the 
 
72 
 
 film is apt to be loosened in developing, and if so will 
 never adhere again properly, or, worst of all, will split 
 off in drying. All these faults appear to occur fre- 
 quently with those kinds of collodion which gives the 
 greatest sensitiveness. The tendency of the film to 
 split off is so great on large plates that nothing but a 
 very powdery and insensitive collodion can be used : 
 varnishing round the edge will prevent the film from 
 washing off, but not from loosening or splitting off 
 when dried. If a preliminary coating be used, this 
 process will give rather more trouble than the pre- 
 paration by the tannin method, and will still leave the 
 quality of the result dependent on the condition of the 
 collodion, as before shown. 
 
 Negatives of the highest degree of excellence may 
 be obtained by the albumen process with some kinds 
 of subjects ; but it is difficult to produce a perfect film, 
 and to dry a layer of sufficient thickness, free from 
 dust. Plates prepared by this process are insensitive, 
 and appear to he quite incapable of taking sky and 
 foliage or dark objects together, without rendering the 
 former pale from solarization. 
 
 Glycyrrhizine, used as a preservative on collodion, 
 appears to be very uncertain in its effect. If the 
 collodion is not in exactly the right state, even when a 
 sample prepared for the purpose is used, the develop- 
 ment is sometimes so feeble, that scarcely anything 
 can be brought out with any exposure. 
 
 After trying in vain to modify the collodion for dry 
 
73 
 
 processes in such a way as to overcome the difficulty of 
 obtaining sufficient adhesion to the plate, without loss 
 of sensitiveness, the writer thought of ascertaining the 
 effect of an exciting hath, containing half its bulk or 
 more of alcohol. This greatly diminished the diffi- 
 culty, rendering the film very non-contractile (even 
 when the collodion was new, and contained a large 
 proportion of ether), and not diminishing the sensitive- 
 ness. For some time this answered well ; but the 
 alcoholic bath gradually acquired the property of dis- 
 solving iodide of silver, and in time this solvent power 
 increased to such an extent as to render a collodion 
 film transparent in a few minutes. Keeping a quan- 
 tity of undissolved iodide of silver in the solution did 
 not entirely prevent the destructive action, even when 
 the iodide was stirred up, and the bath used in a turbid 
 state. After being evaporated nearly to dryness, and 
 re-diluted, the bath worked well again. Something 
 like the above-described action, in a modified degree, 
 often takes place in a bath which has acquired much 
 alcohol from the collodion forming on the excited film 
 streaks of less opacity in the direction of the dip. 
 When this tendency has become so strong that it can- 
 not be counteracted by moving the plate laterally 
 immediately after immersion, the solution should be 
 boiled in an open thin glass, or porcelain vessel, over a 
 lamp, till most of the alcohol is driven off. The lamp 
 should stand in a dish large enough to hold the nitrate 
 solution, in case of accident. After being boiled, the 
 
74 
 
 bath can again be diluted with water to the proper 
 strength. 
 
 It seems desirable in most, if not all, dry collodion 
 processes to use some preliminary coating to secure 
 adhesion, and thus to render us independent of the 
 exact mechanical state of the collodion. Several such 
 coatings have been proposed. India-rubber, dissolved 
 in benzole, answers the purpose so far that it usually 
 prevents blistering and loosening from the glass ; but, 
 unfortunately, as soon as the finished and dried nega- 
 tive is warmed for varnishing, the film often splits in 
 cracks all over, without being detached from the plate : 
 this is probably the effect of unequal contraction. 
 Wax, dissolved with the India-rubber, tends to prevent 
 the liability to split, but produces a dull, granulated 
 surface ; and some of the wax is dissolved by the ether 
 in the collodion, producing in the latter, if present in 
 any considerable quantity, a tendency to gelatinize on 
 the plate from precipitation of the wax by evaporation 
 of ether : this state of things gives rise to a mottled 
 texture. Marine glue dissolved in benzole, in which it 
 is very sparingly soluble, is even more addicted to 
 cracking than India-rubber. Albumen is sometimes 
 used for this purpose, but, in its ordinary state, is not 
 to be recommended ; for not only does the first contact 
 of the collodion render it permanently insoluble and 
 incapable of afterwards swelling, like gelatine, into the 
 pores of the collodion ; but it is too close in texture for 
 the collodion to penetrate, and the adhesion of the 
 
75 
 
 latter is therefore imperfect. Albumen has also a far 
 more injurious effect on the bath than gelatine, and it 
 can be easily proved that the nitrate solution penetrates 
 beneath the collodion by coating a glass with meta- 
 gelatine (which is readily soluble in cold water), drying, 
 covering with collodion and dipping in the exciting 
 bath, when, in a short time, the solution of the meta- 
 gelatine will be made evident by the loosening of the 
 film. Again, the effect of the albumen, acted on by 
 nitrate of silver, is likely to be prejudicial to the pic- 
 ture; for the same soluble matter which injures the 
 bath will, if any of it remain in the film, cause rapid 
 deterioration by keeping, liability to fogging, and a 
 muddy, yellow tone in the negative. The above-named 
 matter shows its presence in imperfectly-washed col- 
 lodio-albumen plates, but is more easily removed from 
 a film of coagulated albumen on the surface than from 
 one below the collodion. 
 
 The following is the method of using albumen 
 referred to in Chapter II. Beat up 1 ounce of albu- 
 men with 30 grains of nitrate of magnesia, or, should 
 this not be at hand in the dry state, 30 minims of 
 strong nitric acid, accurately neutralized with magnesia 
 or carbonate of magnesia ; dilute with 3 to 5 ounces of 
 water, and filter. The nitrate of magnesia is not 
 necessary, but appears to facilitate the coagulation of 
 the albumen, and to render its adhesion more perfect 
 both to the glass and to the collodion, particularly to 
 the latter, by making the surface more porous (though 
 
76 
 
 the washing alone, after coagulation, will secure this to 
 a great extent). Coat the glasses and dry exactly as 
 described in the case of gelatine. When the plates 
 have been dried for a short time, at a heat of 100° to 
 120° (a little hotter than the hand), plunge them, still 
 warm, into a dipping hath, containing 30 grains of 
 iodide of cadmium to each ounce of water and as much 
 iodine as will dissolve. After about one minute re- 
 move from the bath, wash under a tap, soak in a dish 
 of water till most of the colour has disappeared, w'ash 
 again under a tap, dry by heat, which will remove any 
 iodine not washed out, and keep and use exactly as in 
 the parallel case of gelatine. The albumen solution 
 will keep any length of time, if a few drops of oil of 
 lemon peel (essence of lemons) be dropped into it, and 
 will be found to improve by age. The iodide solution 
 simply requires filling up as it wastes by use, but 
 should be kept in a bottle, to prevent evaporation of 
 the iodine. The albumen film, prepared as above, will 
 enable us to use a new and horny collodion for any dry 
 process, and the albumen appears to be without effect 
 on nitrate of silver, consequently no fear need be 
 entertained of its injuring the bath. Gelatine, how- 
 ever, answers so well when tannin is used, that it is 
 questionable whether it is worth while to adopt a 
 method involving so much additional trouble. The 
 only fault which can be found with the coagulated 
 albumen film, beyond the trouble of preparing, is the 
 difficulty of removing it when the glasses are cleaned 
 
77 
 
 after taking negatives ; carbonate of soda acts bnt 
 slowly, even when used in strong warm solution. 
 
 Gelatine may be used instead of albumen as a pre- 
 liminary coating for other dry processes, and will 
 answer tolerably well with some kinds of collodion. 
 With other kinds, however, it is not to be depended on, 
 as it is liable to be dissolved or softened too much in 
 the different washings, or during development, unless 
 this be prevented by the coagulating effect of tannin. 
 
 A thin film of gelatine, dried and rendered insoluble 
 in a strong solution of tannin, may be used with suc- 
 cess in many dry processes ; but this method is as 
 troublesome as that already described with albumen, 
 and is likely to injure the bath by the introduction of a 
 trace of tannin. 
 
 It was during his experiments with gelatine, as a 
 preliminary coating, that the writer, about a year ago, 
 first thought of trying the effect of tannin on dry collo- 
 dion. Having for years been in the habit of using gallic 
 acid with all dry processes, either mixed with the pre- 
 servative solution or as a final wash, to facilitate the 
 development and increase the brightness of the picture, 
 and render it less liable to solarization, it struck him 
 that tannin, a body of somewhat similar nature, might 
 answer the same purpose. It was accordingly substi- 
 tuted for gallic acid, in a solution of gum arabic — at 
 first in small proportion. This experiment proving 
 successful, the tannin was afterwards used in the same 
 way in larger and larger proportion, with the effect of 
 
78 
 
 still further improving the negatives. Eventually the 
 tannin solution was employed alone, and apparently 
 with advantage ; for although gum arabic, mixed with 
 tannin solution, gives a little more sensitiveness to the 
 dark parts of a feebly -lighted subject, there is always, a 
 greater tendency to fogging, particularly when the pic- 
 ture contains mueh sky, or strongly-lighted objects. 
 Citric acid in the solution corrects this tendency, but 
 probably destroys any extra sensitiveness otherwise 
 obtainable. 
 
 Gum arabie used alone produces less tendency to 
 blistering than metagelatine, but more than tannin ; 
 and its partial substitution for, or addition to, tannin 
 solution, gives a slight tendency to blistering or loosen- 
 ing of the film, even when gelatine has been used as a 
 previous coating. Again, the gum, unless thoroughly 
 washed out, renders the developer turbid in cases 
 where tannin would have no such effect, and solution 
 of gum does not filter so easily as that of tannin. 
 Hence, on the whole, it seems better to use the latter 
 alone, as it fulfils every requirement, acting mechani- 
 cally in keeping open the pores of the collodion, and 
 giving, perhaps more effectively than any other known 
 substance, that organic reaction without which a sen- 
 sitive collodion cannot be worked when freed from 
 nitrate of silver and dried. If 30 grains of tannin to 
 the ounce be used, the film will be restored to a very 
 porous condition when moistened previous to develop- 
 ment, as will be shown by its whitening; and the 
 
79 
 
 development will then be very rapid and energetic. 
 The action of tannin in stimulating the development 
 is most remarkable, being much greater than that of 
 gallic or pyrogallic acid used in the same way, although 
 the first-mentioned substance is a far feebler reducing 
 agent than either of the others ; indeed, tannin has 
 scarcely any developing power, even when mixed in 
 strong solution with a large proportion of nitrate of 
 silver, and if applied to a plate fully exposed in the 
 camera it will only bring out the sky faintly in an hour 
 or so. The properties of tannin and gallic acid differ 
 also in another respect: if we increase the strength of 
 tannin solution on new and sensitive collodion, it will 
 give increased vigour and intensity from 1 grain to 30 
 grains to the ounce of water; whilst gallic acid acts 
 very differently, showing a kind of alternating action. 
 This is not seen on applying the solution of different 
 degrees of strength up to saturated solution in 
 cold water to collodio-albumen plates, either because 
 the greatest strength does not go beyond the limit of 
 greatest intensity, or because the film does not retain 
 enough gallic acid to pass that limit, the remainder 
 crystallizing out. If, however, we dissolve gallic acid 
 in the proportions of 1, 2, 3, and 4 grains to the ounce 
 in different portions of a solution of metagelatine con- 
 taining alcohol, and coat with these four excited and 
 washed collodion plates, we shall find, on development 
 after similar exposure, that within these limits the 
 increase of gallic acid first promotes and then dimi- 
 
80 
 
 nishes intensity. Again, this alternating action may 
 be shown in the following manner : — Excite a piece of 
 iodized Talbotype paper, remove the nitrate by washing 
 well in common water, dry, and fold in three equal 
 parts ; float the middle part on saturated solution of 
 gallic acid in cold water, then immerse the part at one 
 end in the same, and hang, till thoroughly dry, with 
 that end downwards which is wet on both sides ; 
 expose in the camera and develop : the middle part 
 will be found to be far more intense than either end. 
 The same alternating action shows its effects, when 
 plates prepared with gallic acid are dried by artificial 
 heat, by the unequal intensity produced. If the 
 strength of the gallic acid solution be that most favour- 
 able to intensity, any concentration by evaporation and 
 heat will produce faintness in the developed image : 
 this effect will be seen in the parts which were the last 
 to dry. If the same alternating action be possessed at 
 all by tannin, the limit of greatest intensity is not at 
 at any rate soon reached. The writer can at present 
 form no hypothesis to account for these phenomena. 
 Perhaps a careful comparison of the action of pyrogallic 
 acid with that of gallic acid and of tannin, in solutions 
 of different strengths, might throw more light on the 
 subject. 
 
 H. GREENWOOD, PRINTER, CASTLE STREET, LIVERPOOL. 
 
GETTY CENTER LIBRARY CONS 
 
 NH 690 R96 186- BKS 
 c. 1 Russell, Charles, 18 
 The tannin process / by C. Russell. 
 
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