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A DESCRIPTION 
 
 OF 
 
 CERTAIN DRY PROCESSES 
 
 IN' 
 
 PHOTOGRAPHY, 
 
 SPECIALLY ADAPTED TO THE USE OE THE TOURIST, 
 
 WITH 
 
 SUPPLEMENTARY NOTICE OF PLANS 
 
 USEFUL TO THE SCIENTIFIC TRAVELLER 
 AND MISSIONARY. 
 
 By GEORGE KEMP, M.D., 
 
 St. Peter’s College, Cambridge, Fellow of the Cambridge 
 Philosophical Society. 
 
 LONDON: 
 
 J. W. DAVIES, 54, PRINCES STREET, LEICESTER SQUARE. 
 LIVERPOOL: 
 
 HENRY GREENWOOD, 32, CASTLE STREET- 
 
 1863. 
 
 The Higlit of Translation Reserved. 
 
PREFACE . 
 
 The contents of this pamphlet may be regarded as a portion of 
 a research, instituted more than three years ago, for the pur¬ 
 pose of investigating the nature of the molecular changes which 
 occur in some of the more obscure departments of photography, 
 and pursued, from time to time, in connexion with the practice 
 of the art as an attractive amusement. Nothing was further 
 from the writer’s thoughts at the time than obtruding himself 
 on the public in connexion with a subject, which, from the 
 complicity of its theoretical details and vast amount of ex¬ 
 perience required in its manipulations, cannot be entered upon 
 by an amateur without feelings of diffidence; this will, lie 
 trusts, be received as an apology for the homeliness of the 
 extracts from his notes, registered at the time of making the 
 experiments alluded to, and which possess sufficient internal 
 ovidence of their being merely intended for private reference. 
 
 It was not without a feeling of self-congratulation that, in 
 process of time, certain plans unfolded themselves by which 
 the writer was enabled to take negative views of objects with 
 comparative certainty, and, by availing himself of the ante¬ 
 cedent labours of others, to work them out in a manner that 
 was not perhaps originally contemplated. After due conside¬ 
 ration, and at the request of many high authorities on the 
 subject, he has now ventured to bring together and publish 
 them, in the hope that others may derive as much gratifi¬ 
 cation from the adoption of the methods suggested for prac¬ 
 tice as he has himself. 
 
 The rapidly advancing season has, also, compelled him to 
 hurry on the publication, and many interesting facts have 
 
IV 
 
 been omitted, which it is desirable to confirm by additional 
 experiments; so far as the theoretical department of the 
 research is concerned, it could not with propriety be intro¬ 
 duced into this pamphlet, to say nothing of the incom¬ 
 pleteness in which it stands at present. A research, indeed, 
 can never be said to be finished; for when the student of 
 nature enters upon a path of specific enquiry, however well 
 he may define the limits of his investigation, cognate branches 
 are sure to present themselves, without some knowledge of 
 which his results must be deficient and obscure. 
 
 As photography is a pre-eminently practical art, appealing 
 at every step to the senses, it will at once be acknowledged 
 that the mere narration of the various processes connected 
 with it is incomplete without illustration in the form of re¬ 
 sults obtained; from the nature of the case, this can only 
 be done by depositing such results with some institution to 
 which any inquirer may refer for information; and the 
 writer proposes, at his earliest leisure, to forward negatives 
 of each of thfi processes alluded to to one or two societies, 
 with this end in view; indeed, in a certain sense, he feels 
 bound to do so, as he cannot enter into private correspond¬ 
 ence on the subject, excepting with personal friends. 
 
 The rationale of the dry processes generally will, it is 
 believed, be deprived of much of its obscurity by recognising 
 the principles laid down at the conclusion of Chapter I.; it 
 is obvious indeed that in all inquiries of this nature, if we 
 can but determine general laws, the knowledge of the extent 
 of their operation, and the phenomena arising therefrom 
 becomes a mere question of time and work. 
 
 G. K. 
 
 Hereford, May mh, 1863. 
 
INTRODUCTION. 
 
 The interest with which any remarks on the various 
 methods proposed for the production of the photo¬ 
 graphic image by means of what are usually denomi¬ 
 nated dry processes are received, and the anxiety to 
 become acquainted with any accession hinted at in the 
 journals specially appropriated to heliographic sub¬ 
 jects, at once prove that the numerous plans already 
 published have not practically justified the expecta¬ 
 tions of those who have adopted them, that a require¬ 
 ment still exists, and that any process of a dry nature 
 which will at all approximate to the wet collodion 
 processes in certainty, perfection of detail, and rapidity 
 of action, will be valued and extensively practised. 
 
 Nor let it be supposed that the writer makes these 
 remarks in a condemnatory manner, or with the 
 slightest disparagement of the labours which have 
 preceded the researches which form the subject of 
 this memoir; on the contrary, having practised all the 
 dry processes to which he could by any means obtain 
 access, he is deeply sensible of the gratitude due to 
 those who introduced these processes, and, notwith¬ 
 standing opposition and most unmerited ridicule, pur¬ 
 sued their course to a practical issue in the production 
 of pictures of the utmost perfection, leaving the con¬ 
 viction on every candid mind that it only needed the 
 experience and tact of the originators to produce 
 ■equally attractive results. 
 
6 
 
 It must, however, be conceded that in most of these 
 processes, from one cause or other, failures of a very 
 unaccountable kind have happened, not merely to the 
 novice and unpractised in the art of photography— 
 for this must occur with any process—but to those 
 who, long habituated to the manipulations of the art, 
 are fully capable of estimating its requirements in the 
 way of cleanly and precise operative detail. 
 
 A remarkable instance of this occurred a few years 
 ago in the case of two operators with the collodio- 
 albumen, then called the Taupenot, process. 
 
 The one of these was a teacher of photography of 
 justly-earned celebrity, a great advocate of the pro¬ 
 cess, who had even compiled a manual for the guid¬ 
 ance of students; the other, a well-known amateur, 
 distinguished for his success in photography and the 
 fastidious care with which he carried on its various 
 operations. A tour in different directions was made 
 by each; in the former case, where we must suppose 
 that every precaution was taken, the result was a 
 signal and of course most annoying failure. The 
 latter, out of forty plates, brought home thirty-nine 
 excellent negatives, the fortieth plate having been 
 broken by an accident in travelling. 
 
 The vast amount of experience which has been 
 acquired since that period, and recorded in the photo¬ 
 graphic journals by disinterested and independent 
 observers, has done much to explain many anomalies 
 which mystified the original labourers in this field of 
 inquiry, and the writer confidently hopes that the 
 observations in this little work may contribute to the 
 removal of others ; but stilly much research and expe- 
 
7 
 
 rimental labour must yet be expended before the sub¬ 
 tleties of this 'pleasing , and, as it is doubtless intended 
 to be, most useful practical art may be fully unravelled: 
 nor, considering the circumstances of the case, can it 
 be otherwise. 
 
 The mind of research in photography, as in organic 
 chemistry, has to deal not so much with masses of 
 matter as with the veriest germs, the molecules of 
 physical existence, but, for the most part, under totally 
 different conditions. 
 
 In searching out the causes which influence the 
 marvellous changes constantly taking place in organ¬ 
 ised bodies, and their issue in the performance of the 
 functions to which they are respectively appointed, 
 the chemical philosopher views these molecules in a 
 state of actual movement. In the phenomena, how¬ 
 ever, which more immediately concern the photo¬ 
 grapher, the molecules of matter are in a state of rest, 
 but in such wise that the slightest of many known 
 disturbing forces immediately sets them in motion, 
 and determines the production of new aggregate 
 forms. The iodide of silver, for instance, in the collo¬ 
 dion film, suddenly exposed to the influence of light, 
 and then returned to darkness, remains to all appear¬ 
 ance iodide of silver still; touch it, however, with a 
 suitable developer, and immediately its molecular 
 structure is broken up, and new physical forms deter¬ 
 mined, so that, in a certain sense, we may consider the 
 molecules in the respective cases as in a dynamical or 
 statical condition, and herein it would appear the 
 limits of inquiry into the rapidity of luminary action 
 on the photographic film are reached. A certain 
 
8 
 
 amount of light stimulus is required to impress the 
 image of an object on the film: if insufficient, no 
 amount of development can give an harmonious pic¬ 
 ture ; but, even when impressed, the successful pro¬ 
 duction of the image in a visible form will be greatly 
 influenced by the means adopted for its development. 
 
 Let the conditions once be determined by which the 
 molecules of the iodide of silver can be placed at 
 rest, indeed, but in an infinitely delicate poise between 
 rest and motion; by which also, when motion has 
 been elicited, it can be submitted to control, and the 
 problem of instantaneous photography, whether by 
 dry or wet processes, will be solved. 
 
CHAPTER I. 
 
 GENERAL OBSERVATIONS ON THE PRINCIPAL DRY PROCESSES OF 
 
 PHOTOGRAPHY-UNMERITED DEPRECIATION OF THE TALBOTYPE 
 
 PROCESS AS ADAPTED TO THE REQUIREMENTS OF THE AMATEUR 
 TOURIST-THE DRY PROCESSES ALREADY PROPOSED MORE CER¬ 
 
 TAIN THAN GENERALLY ADMITTED, WITH CAUSES OF FAILURE— 
 CHARACTER OF NEGATIVE REQUIRED-ALLUSION TO ATMOS¬ 
 PHERIC INFLUENCES, WITH ILLUSTRATION-CERTAIN PRECAU¬ 
 
 TIONS NECESSARY IN THE PREPARATION OF ALL DRY PLATES, 
 WHICH ARE REFERRED TO TWO CLASSES. 
 
 The wonderful discovery and introduction of the collo¬ 
 dion film, as a vehicle for the sensitised iodide of silver, 
 by Archer, soon led to the conviction that if the sensi¬ 
 tised plate could be retained in a condition for receiving 
 an illuminated impression, even for a few hours and at 
 a sacrifice of some degree of its sensitiveness, the 
 sphere of its usefulness would be much enlarged, and 
 to effect this object various methods were brought 
 forward. 
 
 The cause of the depreciation of the sensitive plate 
 was well known; a concentrated solution of nitrate of 
 silver dissolves, practically speaking, the iodide of 
 silver, and the main source of sensitiveness is at the 
 same time destroyed. To obviate this, the solutions 
 of certain deliquescent salts, such as the nitrate of 
 magnesia, were introduced as a coating, and thus a 
 weak solution of nitrate of silver was evenly retained 
 
10 
 
 on the surface of the plate: a more convenient method 
 was about the same time introduced by Mr. Shadbolt 
 in the form of honey reduced to a semi-fluid state by 
 means of distilled water, and this method, although 
 apparently seldom used at present, offers an important 
 resource to the practical photographer. It soon became 
 apparent, however, that a great improvement would 
 arise from producing plates actually dry; the immunity 
 from particles of dust, and the increased hardness of 
 the film, rendering it less exposed to injury in travel¬ 
 ling. In the course of experiment by various persons 
 engaged in the same line of research, gum, albumen, 
 gelatine and its analogue, meta-gelatine, with many 
 other substances, were fallen upon, proving sufficiently 
 the much greater superiority of the respective dry 
 processes to those of paper; still, however, leaving 
 much to be desired and hoped for. The comparative 
 slowness of action of these plates compared with wet 
 collodion, the different stages of preparation with risks 
 attendant on each, and, when albumen was employed 
 as a vehicle for a new layer of iodides and bromides, to 
 be resensitised in a separate bath, the rapid discolour¬ 
 ation of the bath rendered these methods repulsive to 
 the operator, and, in combination with many other dis¬ 
 advantages to the practical photographer, dry processes 
 lost favour, and tent operations, with the usual wet 
 collodion plates, supplied their use. Unfortunately, the 
 amateur tourist, to whom time and a compact arrange¬ 
 ment of travelling apparatus are of the last importance, 
 was thus excluded from the enjoyment of the art, and 
 the paper processes, which would in many respects 
 have supplied the place of the more perfect collodion 
 
11 
 
 process, became so depreciated that the amateur consid¬ 
 ered them unworthy of practice—a great mistake ; for, 
 independently of the really excellent results which have 
 and may be produced by their means, the steady and 
 systematic working out of the Talbotype process is far 
 more adapted to the initiation of the student into the 
 leading principles of photography than the collodion 
 process, and the adept in this paper method will enter 
 upon the more perfect collodion process with some 
 confidence and a full appreciation of the great nicety, 
 both with respect to cleanliness and manipulation, on 
 which the successful practice of the art depends. 
 
 To return, however, from this digression. Having 
 alluded to the albumen processes, it should have been 
 mentioned that the resensitising of the albumen is 
 unnecessary, as it was discovered that the mere pour¬ 
 ing of diluted albumen on the washed collodion film 
 was sufficient for its preservation in a sensitive state, 
 and this, denominated the Fothergill, is, for the ama^ 
 teur, one of the best, if not the best, of those preserva¬ 
 tive processes in which this class of animal fluids called 
 proteine compounds is employed. 
 
 As a general remark it may be stated that most, if 
 not all, of the dry processes above alluded to are more 
 certain and capable of giving far better results than 
 generally supposed; the fact is that they have been 
 employed principally by amateurs, and, in many cases, 
 by those who have not laboured in the higher depart¬ 
 ment of chemical research, organic chemistry, and have 
 not in consequence estimated the delicate nature of 
 the changes which take place in the simplest operations 
 of photography, far less recognised the multiplication 
 
12 
 
 of sources of error in each one of the numerous stages 
 necessarily involved in the most easily prepared plates, 
 such for instance as those of Major Russell’s excellent 
 and certain tannin process. The evil has been much 
 increased by not keeping to one plan of operation, and 
 working it out to its utmost practicable limits; any 
 proved dry process may by such means be pressed into 
 the amateur’s service. It may, indeed, require long 
 exposure, slow development, and then look very shabby 
 by the side of the pre-eminently beautiful works of 
 Bedford or Wilson; and these distinguished artists 
 have doubtless met with many a disappointment, many 
 a failure, much hard and tiresome toil in working before 
 they succeeded in producing the types they have done 
 for their successors; still the result obtained will be 
 truthful representations of scenes and objects amply 
 repaying the labour bestowed upon them. Errors of 
 another kind are also constantly made in the all-im¬ 
 portant developing stage of operations. Through a 
 sanguine but fruitless attempt to fall into a royal road 
 to photographic success, every new suggestion is 
 eagerly snapped at, salts of iron are applied where 
 only pyrogallic acid, or even the old but valuable gallic 
 acid, suits the case, the unfortunate plate is fumed with 
 ammonia, treated with formic acid, &c., all very valu¬ 
 able resources to the experienced photographer, but 
 dangerous appliances when used empirically without 
 a knowledge of the theoretical principles which adapt 
 them to their respective cases; and, to complete dis¬ 
 asters, when the image has been well brought out it is 
 more rapidly expunged by cyanide of potassium where 
 hyposulphite of soda is specially directed and can 
 
13 
 
 alone be safely used. It is not, however, tlie mere 
 fact of producing an image which is aimed at in a 
 negative by any given dry process, the character of the 
 negative as to capability of resisting light is of primary 
 importance; this fact is well recognised in the moist 
 process, and the practised eye will at once select a 
 good printing negative from others which appear much 
 darker and promise to the uniniated better results. The 
 same fact holds good and perhaps with greater force 
 in dry photographic plates, and the amount of actinic 
 resistance possessed by some of these processes in 
 apparently weak negatives is very striking; the mis¬ 
 fortune, however, is this—that in most cases insensi¬ 
 tiveness to impression in the camera is the general 
 character of such. Thus, for instance, in the well 
 known collodio-albumen process which stands very 
 high in the list of preservative plans, immediately the 
 details of the picture are well out, no apprehension need 
 be entertained as to its printing capacity; to go on 
 developing after this point has been attained, is only 
 needlessly to risk damaging the film. In these plates 
 the principal point to be aimed at is to give them 
 abundant exposure, and although various methods 
 have been published for more rapidly and indeed, as it 
 is asserted, instantaneously bringing out the image 
 from almost instantaneous exposure, the amateur tour¬ 
 ist will not be wise to risk his negatives on the faith of 
 what may after all be limited experience under excep¬ 
 tional conditions. There are many other methods 
 which give far more rapid results than that alluded to; 
 but, however convenient they may be in this respect, 
 and although the amount of detail may be all that can 
 
14 
 
 be desired, few can be compared to that process for 
 the reliableness of the negative in its printing capacity. 
 
 Of course the writer alludes merely to those methods 
 which are published; dry plates are now extensively 
 sold as a commercial transaction; but if they entirely 
 met the views of the photographic public in rapidity 
 of action, certainty of operation, actinic resistance and 
 economy, no anxiety would be felt for any fresh hints 
 on the subject, and the writer might save himself the 
 trouble of adding another line: the matter, in fact, 
 would no longer be a subject for research but a case 
 decided. 
 
 Certain points with reference to atmospheric condi¬ 
 tions, also, will not be considered unworthy of atten¬ 
 tion; and the following summary remarks are offered, 
 principally with the view of eliciting further observa¬ 
 tion. It must have frequently occurred to the tourist, 
 especially employing dry plates, that on certain bril¬ 
 liant days, when he may have been fearful that he has 
 over-exposed his plates, the results in the operating 
 room prove that, on the contrary, sufficient time has 
 not been given in the camera. It has long been known, 
 and recorded by high authorities, that fine sunny days, 
 with cloudless skies, are by no means the most favour¬ 
 able for photographic work; but this is not exactly the 
 state of atmosphere alluded to, and the precise mean¬ 
 ing of the writer may perhaps be better ascertained 
 by an instance. 
 
 Last month (April 20th) a few plates, prepared as 
 described in the sequel, were taken out on a tour to a 
 secluded spot in Monmouthshire, Llanthony Abbey; 
 the day broke loweringly, but, as the plates alluded to 
 
15 
 
 are very good servants in cloudy weather, and as the 
 general character of certain mountain scenery is more 
 faithfully depicted in such weather, the trip was not 
 postponed. Arriving at the Llanvihangel Station, the 
 nearest point by rail to the Abbey, rain began to fall; 
 but, as the writer has obtained capital negatives under 
 shelter of an umbrella, forward was the order of the 
 day, which, as it advanced, cleared up charmingly, 
 and, long before the proposed point was reached, 
 nothing remained but a few clouds capping the Scyrrid 
 Yach, with here and there a cirro-stratus floating upon 
 the azure blue. The little wind there was blew from 
 the N. E., and, when we came upon the venerable pile, 
 although every crevice and projection stood out in bold 
 relief, and the abbey was in fact beautifully illumin¬ 
 ated, former experience indicated the necessity of 
 longer exposure than usual; forty-five seconds there¬ 
 fore were given to three of the four plates taken out, 
 and seventy to the fourth, which took in the northern 
 side of the ruin. On returning to develope in the 
 evening, it was found that all the plates, although 
 good negatives were obtained with appropriate treat¬ 
 ment, would have been better for ten seconds’ more 
 exposure; and, taking all circumstances into consider¬ 
 ation, the writer suggested to his companion the pro¬ 
 bability of the wind chopping round to the S. W., 
 with a cyclonic storm, which, as is well known, took 
 place on the following evening, producing great dis¬ 
 asters on the coast. This is but one of many instances 
 of a similar nature which have been observed, and it 
 seems by no means improbable that the condition of 
 the atmosphere in respect of actinism may become an 
 
16 
 
 important element in meteorological observations; at 
 any rate, no great extra trouble would be expended 
 on taking an occasional note on the subject, and thus 
 photography may in this, as it has, in other ways, 
 become no mean accessory to the advancement of 
 physical science. 
 
 The time of year, too, requires consideration; and 
 on this point much remains to be done in the way of 
 research. It has long been known that great variety 
 of effects are produced in different months and at 
 different hours of the day, and the fact is registered 
 in the Photographic News Almanac as a guide to be 
 referred to in practice; indeed, it will be observed in 
 the sequel, that methods which gave excellent results 
 during the winter and early spring months, with 
 thirty seconds’ exposure, require quite as long, if not 
 a longer exposure at this time (May 6th); whilst, 
 on the contrary, methods unserviceable, or rather re¬ 
 quiring longer exposure when the sun’s rays formed a 
 more acute angle with the horizontal plane, are now 
 showing much activity. This fact alone points out the 
 extreme caution which, in the present state of our 
 knowledge of the theory of actinic operations, should 
 be observed in anything approaching to dogmatism or 
 sweeping generalisations; there can be little doubt 
 that to these we may trace much of the want of con¬ 
 fidence which is so generally felt in receiving novel 
 propositions in this department of inquiry. Many 
 valuable facts have lost their significance from not 
 determining the precise conditions under which they 
 became elicited; and, not unfrequently, from the 
 exalting of a mere incident into the cause of their 
 
17 
 
 appearance. This mistake is, of all the operations of 
 photography, most likely to occur in the preparation of 
 dry plates: a great number of substances is neces¬ 
 sarily used, and even in the hands of the most careful 
 and experienced operators, accidental phenomena may 
 occur, which, unless jealously checked by experiments, 
 may be magnified into undue importance; or, on the 
 other hand, mere suggestive appearances, which, if 
 diligently worked out, might result in the discovery 
 of invaluable principles, stand the chance of being 
 altogether lost sight of. If this be considered a dolor¬ 
 ous view of the case, the writer can only say that it is 
 the result of some thirty years’ study in a somewhat 
 allied department of research, organic chemistry; but 
 he is bound at the same time to add, that, notwith¬ 
 standing all the labour, disappointment, and discour¬ 
 agement that must ever attend upon abstruse re¬ 
 searches, the gratification of establishing a fact, and 
 feeling that he can conscientiously recommend it as 
 such to others, is more than a return for his pains. 
 And now—having made these general statements—to 
 prevent their interrupting the course of more specific 
 description, we will just remind the reader that two 
 classes of sensitive surfaces exist, to one or other of 
 which we may refer all the processes which come 
 under the domain of photography. 
 
 1. We have a surface so prepared that, having been 
 exposed to the influence of light, the iodide of silver 
 remains in a quiescent state, until stimulated into 
 action by a developer; to this class belong the usual 
 wet collodion and most of the dry processes. 
 
 2. In addition to such a surface, we introduce a 
 
 B 
 
18 
 
 substance which not only places the iodide of silver 
 in a condition to be acted upon by a developer, but 
 initiates the action during the exposure of the surface 
 to light. The Talbotype paper and dry tannin pro¬ 
 cesses of Major Russell are instances of this latter 
 class; and the methods proposed in the following 
 chapters will illustrate both of these divisions. 
 
CHAPTER II. 
 
 MR. MACNAIR’s PROCESS, WITH GENERAL DESCRIPTION, RESULTS, 
 AND REASONS FOR DEPARTURE FROM DIRECTIONS AS TO TEM¬ 
 PERATURE AND SUBSEQUENT TREATMENT OF PLATES-THEO¬ 
 
 RETICAL CONSIDERATION OF THE PROCESS, AS DEDUCED FROM 
 
 THE CHEMICAL CONSTITUTION OF THE MATERIALS USED - 
 
 REASONS WHICH SUGGESTED THE USE OF THIS PROCESS- 
 
 LABORATORY EXPERIENCE, WITH FORMULAE FOR PREPARATION, 
 
 AS DICTATED BY RESEARCH-REMARKS ON VARIOUS POINTS 
 
 NECESSARY TO BE OBSERVED FOR CARRYING OUT THE WRITER’S 
 
 PLAN-PROPERTIES OF THE PREPARED PLATE IN RELATION TO 
 
 STABILITY, SENSITIVENESS, FIRMNESS OF FILM, &C., &C. 
 
 The announcement to the Photographic Society of 
 Scotland, in the Spring of 1860, that a new dry collo¬ 
 dion process, matching the ordinary wet process in 
 sensitiveness, had been discovered by Mr. John Mac- 
 nair, excited the hopes of all who take interest in the 
 practice of photography that, at last, a method was 
 produced which would enable the tourist to dispense 
 with the cumbrous paraphernalia necessary for the 
 ordinary wet process, and give him an opportunity of 
 taking a class of objects which was necessarily ex¬ 
 cluded from the dry processes hitherto proposed, on 
 account of the slowness of their action; and, amongst 
 others, the writer was induced to adopt it, not merely 
 on account of its promise in a photographical point of 
 view, but because the substance employed, from its 
 known chemical characteristics, seemed to indicate an 
 
20 
 
 opening into mysteries involved in the character of 
 the molecular changes which occur in the course of 
 all photographic operations. 
 
 The substance proposed by Mr. Macnair was malt , 
 infused in water with a certain amount of precaution 
 as to temperature. A notice of this method was thus 
 introduced by a high authority on these subjects.* 
 
 “ Another dry process is now attracting great atten¬ 
 tion in Edinburgh, and is due to Mr. Macnair. It 
 consists in using infusion of malt as a preservative, 
 and great sensitiveness is said to be obtained in this 
 way. A variety of substances has been used as 
 preservatives ; for instance, albumen, gelatine, honey, 
 golden syrup, raspberry vinegar, oxymel, gum arabic, 
 serum of milk, pale ale, and, lastly, infusion of malt. 
 There are no doubt slight differences of action amongst 
 these substances; but we do not see at present why 
 infusion of malt should be superior to the other pre¬ 
 servatives named.” 
 
 The writer took a different view of the matter, and 
 for the following reasons. All the substances which 
 play an important part in the production of the photo¬ 
 graphic image are either aggregate forms, the mole¬ 
 cules of which are held together by very slight 
 chemical affinity, or they are the derivatives of such; 
 and it would be difficult to name a substance in which 
 these two properties are more remarkably united than 
 in the case of malt. We are acquainted, for instance, 
 with a variety of substances, differing widely in their 
 appearance as to physical characters, but all comprised 
 ^between the limits of the formulas, C 12 H 9 0 9 , and 
 
 * Photographic Quarterly Beview, by Mr. Sutton, June, 1860. 
 
21 
 
 C io H 14 0 14 , differing, in fact, in elementary compo¬ 
 sition only as to the quantity of the elements of water 
 which they contain; thus, dextrine or British gum, 
 C H 10 0 10 , only differs from starch C 12 H 9 0 9 , in 
 containing the elements of one equivalent of water; 
 cane sugar C 12 H X1 O tl , in containing the elements 
 of two equivalents of water; crystallised sugar of 
 milk, C 12 H 12 Oj 2 , in containing the elements of three 
 equivalents of water; and so on to the sugar of fruits, 
 C,„ 0,„, which contains the elements of five 
 
 equivalents of water. 
 
 Now malt contains, not only the radix of this series 
 — starch —which is capable- of being thus transformed, 
 but it contains, in rich abundance, this radix actually 
 transformed into some of the substances above alluded 
 to, but pre-eminently disposed to still further disinte¬ 
 gration, from the very circumstance of its containing 
 within itself the catalytic body which, above all others, 
 effects these changes with infinite rapidity, and, for 
 that reason, called diastase , with such energy, moreover, 
 that a single part of this substance is capable of con¬ 
 verting 2000 parts of starch, first into dextrine, event¬ 
 ually into grape sugar. Certain conditions, indeed, are 
 necessary, and these are generally supposed to be 
 very simple, but are, in fact, mightily effective engines 
 in all organic changes —heat and moisture. Nor will 
 it escape observation that two of the substances above 
 mentioned, gum and grape sugar, are familiar to us 
 as agents employed from the earliest days of photo¬ 
 graphy, grape sugar especially, as what was supposed 
 to be an accelerator, and, at one time, much recom¬ 
 mended in the wax paper process—an accelerator 
 
certainly in one sense, as tlie writer can testify, for it 
 lias a marvellous tendency, in slow development, to 
 produce excessive action in tlie developer and to cause 
 the silver to be deposited, not only on the points 
 acted upon by light, but over the whole surface, thus 
 destroying the purity of the whites and damaging, 
 if not spoiling, the negative. Again, collodion itself 
 is the derivative of a body, cotton , closely analogous in 
 its chemical composition to starch, and coming within 
 the series of compounds to which we have alluded : 
 analogy, then, was not urged beyond its legitimate 
 bounds in suggesting that the powerful catalytic body, 
 diastase , might, even in collodion itself, effect a change 
 highly conducive to initiating or accelerating changes 
 in the iodide of silver under the influence of light. 
 Such were the motives which induced the writer to 
 experiment upon the malt process of Mr. Macnair; and, 
 of course, the first step was to take up his formula 
 literally as given by him. 
 
 Three years have now elapsed, and, until lately, 
 little has been heard of this subject; but from various 
 causes, it is now attracting some attention, and with the 
 very considerable deviations from the plan as originally 
 proposed, and which the writer is about to describe, 
 he believes it will be generally found much quicker 
 than most others hitherto described in its operation; 
 at the same time giving a clean negative of excellent 
 printing capability. The amount of detail and general 
 harmony of the picture wdll much depend upon the 
 collodion, nitrate of silver bath, and other conside¬ 
 rations which will meet with due attention in the 
 subsequent portion of this pamphlet. 
 
23 
 
 A leading article in No. 189, May 1st, 1863, of The 
 British Journal of Photography, contains a reprint 
 of the instructions for the preparation of the malt 
 infusion, communicated to the Photographic Society of 
 Scotland, by Mr. Macnair; and, as this work is in the 
 hands of all photographers, it is not necessary to 
 repeat them. It must, however, be remarked, that in 
 one particular point to which Mr. Macnair attaches 
 importance, a discrepancy exists from that originally 
 given, or, at any rate, from the formula used by the 
 writer and taken from Mr. Sutton’s Photographic Quar¬ 
 terly Review for June, 1860. The limits there stated are 
 from 155° to 158° F., and it was with an infusion thus 
 made, observing the original directions in every other 
 respect to the letter, that the experiments of the 
 writer were first made. Every precaution was, of 
 course, taken as to bath, condition of collodion, &c., 
 and a plate treated in the moist way as a standard. 
 It Avould be wearisome to follow up the details as 
 recorded at the time; but the issue of many different 
 samples of infusion was unsatisfactory. The image 
 indeed came out well, and the time of exposure was 
 little more than that of slow collodion. The negative, 
 however, was far too thin and non-resistant of diffused 
 light; and, in fine, the writer-abandoned the process 
 as described. Still the theoretical suggestions above 
 stated seemed so inviting that the original plan was 
 modified: in the first place by dispensing with the 
 iron developer, and substituting pyrogallic acid, the 
 advantage was marked; still, the uncertainty of ob¬ 
 taining uniform results as to the preparation of the 
 malt infusion was annoying, and a few hours entirely 
 
24 
 
 changed the character of the preservative; in fact, 
 lactic acid fermentation took place, and, contrary to ex¬ 
 pectation, the action now set up destroyed the hopes 
 of doing anything in this direction. 
 
 Passing over many other experiments, of which 
 copious notes were taken, the writer finds the following 
 entry in his journal book, bearing date April 6th, 1861. 
 
 Section 133. 1. Recently crushed pale dried malt 
 
 was mixed with cold water into a thick paste, and 
 water at 212 F. added, with continual stirring, until 
 it was thin; the whole was then placed in a moder¬ 
 ately heated oven and left to infuse for some hours; 
 having strained through muslin, the fluid was placed, 
 with its containing vessel, in boiling water, and kept 
 at that temperature until the albumen separated, it 
 was then strained. 
 
 2. As a preservative fluid, this was found too con¬ 
 centrated. 
 
 3. Diluted with half water, it answered well, but 
 better, 
 
 4. When another half bulk of alcohol was added, 
 boiled and strained, &c., &c. 
 
 Section 134. The mode I pursued, with the greatest 
 advantage, is as follows:— 
 
 1. Sensitise in the usual way. 
 
 2. Remove by careful washing the whole of the flee 
 nitrate of silver. 
 
 3. Pour on and off the preservative solution and 
 wash thoroughly. 
 
 4. 5, 6, 7. These must be omitted here, although 
 alluded to hereafter, as the writer wishes to fix the 
 attention of the reader on the words wash thoroughly. 
 
25 
 
 In former processes, excellent of their kind, the 
 neglect of this precaution brought them into disfavour; 
 a purposed neglect of course, because the idea pre¬ 
 vailed, that the more nitrate of silver present in a dry 
 plate the quicker must be the impression of the object 
 sought, and by far the denser the negative. All this 
 is a mistake. Wash a Fothergill plate as long as the 
 film will safely bear it, and you will secure far better 
 results than when loaded with chemicals; and in the 
 malt process, as it afterwards proved in the tannin pro¬ 
 cess of Major Russell, this innovation led to success. 
 
 Regarding the above description, it seems rash to 
 mix the water with the malt at the boiling point, for 
 it is well known that, in the ordinary process of brew¬ 
 ing, if the water be added at too high a temperature, 
 the several particles of the malt are not disintegrated; 
 a pasty mass is formed, and the action of the diastase 
 is confined to the few superficial particles with which 
 it comes in contact; the quantity operated upon, how¬ 
 ever, in this case, amounting only to a few ounces, 
 with the additional precaution of constant stirring, 
 obviated this disadvantage, and, having previously 
 soaked the malt in cold water, not only was the tem¬ 
 perature suddenly lowered many degrees, but the hot 
 water obtained easy access to the whole mass. 
 
 And now, so far as the malt process is concerned, 
 no difficulty can arise to any one at all accustomed to 
 operations of this nature; as these experiments, how¬ 
 ever, were made two years ago, they have just been 
 repeated, with every precaution, and the writer can 
 now, with confidence, recommend the following for¬ 
 mula :— 
 
Take two ounces of malt, crushed in a mill, and 
 break it up still further by passing over it several 
 times an ordinary roller, such as is used for making 
 pastry; pale malt should be preferred, because in high 
 dried malt much of the starch is converted into 
 British gum, and a very viscid infusion is produced, 
 not adapted to the purpose contemplated. Place the 
 malt, thus bruised, in an earthenware jug, or any other 
 suitable vessel, and pour on it, by degrees, two fluid 
 ounces of lukewarm water, with constant stirring, and 
 let the whole be kept in a warm, but not hot, place for 
 a quarter of an hour, a cool kitchen oven answers the 
 purpose well; in the meantime raise eight ounces of 
 distilled, or, at any rate, pure rain, water to the boiling 
 point, and pour it on the malt, soaked as above, con¬ 
 stantly stirring; cover the vessel and return it to a 
 warm situation, and thus it may be left for two hours, 
 by which time the fluid will have entirely changed its 
 character and become sweet; it may now be allowed 
 to cool for an hour, and then the whole contents of 
 the vessel should be emptied on a canvas or hair 
 strainer, a common sieve in fact, and, wdien the fluid 
 has run through, a couple of ounces more distilled 
 water should be quietly poured on the pasty mass, 
 and thus the infusion which it retains will be princi¬ 
 pally removed by displacement. It is very important 
 to pay attention to the quality of the w r ater, and negli¬ 
 gence in this respect has in more than one instance led 
 to the rejection of this process; of course, if chlorides 
 or carbonates be contained in. the water, which is 
 almost invariably the case with ordinary hard water, 
 the plates, when treated with the preservative fluid, 
 
27 
 
 will necessarily be rendered insensitive from the for¬ 
 mation of chlorides or carbonate of silver, in the 
 original plan; the subsequent preparation, however, 
 of the preservative fluid, by the writer’s method, will 
 prevent the possibility of the latter salt being formed. 
 On resting for a short time, the strained fluid will have 
 deposited a thick sediment, from which the clear 
 supernatant fluid should be poured; it is not necessary 
 to filter it, which is a very tedious process, and, with 
 the quantities above proposed, fluid enough may be 
 poured oft’ to coat three dozen stereoscopic plates. 
 Pour the fluid, thus obtained, into a Florence flask, o* 
 such vessel, add ten drops of glacial acetic acid, 
 agitate, place the flask in a water bath and raise to 
 the boiling point, retaining it at this temperature until 
 the fluid in the vessel boils well, it may then be 
 allowed to cool. As it cools, we shall again find a 
 fluid and sediment, which, as above, may be separated 
 by decantation; add half an ounce of alcohol and the 
 preservative fluid is prepared, requiring, however, in 
 most cases to be strained, though it is useless to filter 
 it, as, even when passed through a filter, it will retain 
 its milky, emulsive appearance, which is no detriment 
 and cannot be removed, excepting by a circuitous, 
 complicated process, and we all know that it is essen¬ 
 tial in photographic operations to keep the conditions 
 as simple as possible. The subsequent steps are those 
 common to all prepared plates, that is to say, the film 
 of collodion is sensitised in the nitrate of silver bath, 
 and thoroughly washed with distilled, or, at any rate, 
 pure rain, water; the preservative fluid is then poured 
 upon it repeatedly and in such a manner as to ensure 
 
28 
 
 its action upon every portion of the surface, and then, 
 deviating from the directions of Mr. Macnair, the plate 
 is introduced into a dish of soft water and allowed to 
 soak for five or ten minutes; it is again washed with 
 a fresh supply of water and placed in a suitable 
 position to drain, resting one corner on blotting paper. 
 In the course of half an hour it may be exposed to 
 heat in any suitable manner in order that it might 
 become thoroughly dry; the plate, in fact, should be 
 heated to such a degree as the hand will just bear, 
 and may then be stowed away for use. 
 
 If these simple directions be followed, no apprehen¬ 
 sion need be entertained of obtaining a good picture; 
 if otherwise, the collodion or bath is in fault: the 
 principal points to keep in view are careful washing 
 and thoroughly coating the plate. In the Fothergill 
 process, for instance, disappointment frequently arises 
 to the inexperienced from neglect in this last particular. 
 The picture is fully impressed, but patches of insensi¬ 
 tive surface cause it to come out unevenly, in conse¬ 
 quence of the whole of the water not having been 
 removed, and the combination of the albumen with the 
 residue of the silver salt being confined to certain por¬ 
 tions of the plate. Now it must be remembered that 
 the film, however carefully washed, always retains a 
 portion mechanically enveloped in its substance, and it 
 is clear that the mere floating of a preservative fluid 
 thereon does not effect the object proposed; it must 
 penetrate the film, in order to form a combination with 
 the oxide of silver on which its preservative properties 
 depend. With reference to the particular proximate 
 principle, out of the many contained in malt, which 
 
29 
 
 produces the action referred to, it is an obscure and 
 difficult question; but, from certain chemical consider¬ 
 ations, it appears to the writer that the efficiency of 
 this preservative fluid mainly depends upon the pres¬ 
 ence of a small portion of vegetable albumen or some 
 other proteine compound not coagulable by heat. 
 Whatever it be, however, it is easily destroyed; and, 
 in the first experiments on the subject, much vexatious 
 disappointment arose from this cause. The plates, 
 made at one particular time, would be excellent, keep 
 well, and for days after exposure remain uninjured; 
 another lot, prepared by the same formula and with 
 apparently every precaution, would prove treacherous, 
 and, at last, a very simple cause explained the diffi¬ 
 culty. It will be remembered that the infusion of 
 malt is boiled , and this has a great tendency to save it 
 from decomposition; still, if the temperature be much 
 above 50°, the fluid cannot be depended upon for more 
 than a day or two ; viscous or lactic acid fermentation 
 occurs and it becomes useless; for this reason the 
 alcohol was added, but still it is very desirable to use 
 it as soon after its preparation as possible. A disad¬ 
 vantage, in one respect, arises from the addition of 
 alcohol; the solution, when first poured upon the 
 plate and then poured off, leaves a streaky surface just 
 as happens for the first few seconds after plunging the 
 collodion plate into the silver bath; the solution then 
 must be poured on and off repeatedly, until this ap¬ 
 pearance ceases, or the result will be development in 
 patches. It is not absolutely necessary to add the 
 alcohol at all if the fluid be used immediately as it is 
 prepared, but the plate is less sensitive. 
 
30 
 
 With reference to keeping qualities; plates thus pre¬ 
 pared, if rigidly secluded from light, damp, and foul 
 air, may be used at any time, at least within the limits. 
 of six weeks; their having been dried at*a high tem¬ 
 perature is a great security against deterioration, and 
 to the same cause perhaps we may attribute the re¬ 
 markable firmness of the film, bearing the succeeding 
 operations after exposure without any risk of break¬ 
 ing away, and never blistering; indeed, as a most 
 useful plate for average out-of-door work, it merits 
 great confidence; the time of exposure, which is 
 much less than for a Fothergill or tannin plate, with 
 more specific directions for development, will be stated 
 in a future chapter, and we now proceed to the 
 description of other processes, connected with the 
 above or arising out of it, by which far greater sensi¬ 
 tiveness is ensured. For the sake of distinction in 
 reverting to the several processes, they will be desig¬ 
 nated by numbers, the above being Process No. 1. 
 
CHAPTER III 
 
 RECOGNITION OF PRINCIPLES LAID DOWN-NATURE OF SECOND 
 
 it CLASS OF SENSITIVE SURFACES-ALLUSION TO MR. TALBOTS 
 
 PROCESS, AND ALSO TO MAJOR RUSSELL’S—ANALOGIES OF 
 TANNIC AND GALLIC ACIDS-GENERAL CHARACTERS AND DE¬ 
 SCRIPTION OF PROCESS II.-EXPERIMENTS ON THE MIXTURE 
 
 OF MALT AND TANNIN ;* SPOILED PLATES—EXTRACTS FROM 
 
 NOTES TAKEN AT THE TIME-PROPERTIES AND DESCRIPTION 
 
 OF PROCESS III.-MOLECULAR STRUCTURE OF GLYCERINEf AS 
 
 COMPARED WITH OXALIC AND FORMIC ACIDS-EXPERIMENTS- 
 
 FORMULA FOR PRESERVATIVE FLUID—PLATES PREPARED SUIT¬ 
 ABLE FOR TAKING INTERIORS-PROCESS IV., ACTION OF FORMIC 
 
 ACID ON THE FILM. 
 
 The subjects now entered upon assume the recognition 
 of the principles laid down at page 17, and our atten¬ 
 tion will be mainly directed to the second class of 
 sensitive surfaces there mentioned; those to which, 
 having provided ourselves with a suitable coating of 
 
 * At the time of making this research the writer was not aware that 
 such a mixture had even been proposed for the dry-plate process, and has 
 not, as yet, been able to meet with any details of its application. In 
 The British Journal of Photography for this month, page 195, it 
 appears that Mr. Fassitt, of Philadelphia, has been experimenting on 
 plates similarly coated, and fuming them with ammonia. The writer 
 has made careful experiments on the plates prepared by his method, and 
 finds that after the thorough washing he urges, no increased capability of 
 development seems to be afforded by exposure to strong ammoniacal gas. 
 
 t The writer finds, in the Photographic News Almanac for the present 
 year, a formula given by Mr. Fysh for the preserving plates by a mixture 
 of honey and glycerine. 
 
32 
 
 iodide of silver on a glass plate, we make the addition 
 of one or other of the substances which experience 
 teaches ns have a tendency to elicit or bring out the 
 image on the plate, which, in fact, sets the molecules 
 of the iodide of silver into motion and induces them 
 to assume a physical condition favourable to the main 
 object which we have in view, the production of a 
 surface which will, in certain places, permit light to be 
 easily transmitted, proceeding through different grades 
 of density, until at last not a ray of light can pass 
 through other portions, even when exposed to the 
 influence of the brightest rays of the midday sun. 
 
 The great epoch of photography as a useful art, 
 that is to say, when it was no longer necessary to 
 proceed through a circuitous and expensive mode of 
 treatment for the reproduction of the facsimile of each 
 individual subject, but when a happy plan suggested 
 itself of multiplying impressions in a simple and 
 economical manner, to almost any extent from one 
 image so taken, was ushered in by Mr. Talbot, and 
 whatever advances may have subsequently been made 
 by the introduction of methods more suited to increas¬ 
 ing requirements, his researches must ever be regarded 
 as those which gave the first impulse leading to the 
 present universal practice of photography, whilst, at the 
 same time, the method proposed by him is, even at 
 present, the only one available for the purpose of the 
 naturalist and other scientific travellers, in situations 
 where the cumbrous apparatus required for the usual 
 collodion process cannot be introduced, and from 
 which results could not be transmitted for multiplica¬ 
 tion. In the present state of our knowledge, many, if 
 
33 
 
 not most of the phenomena, which exhibit themselves 
 in the processes alluded to, are involved in much 
 mystery; and this must be expected, not only from 
 the impossibility of putting the changes which occur 
 in a condition to be observed, but also from the very 
 minute quantities of matter on which we are called to 
 operate. Much, however, has been done by sound 
 philosophical deduction, and much more challenges 
 the attention of the philosophical inquirer in the way 
 of research. 
 
 It is well known that in the Talbotype process a 
 very delicate coating of iodide of silver is first ob¬ 
 tained on a surface of paper, and that, when it is 
 desired to impress an image on this surface, previously 
 to exposing it to light, it is moistened with a weak 
 solution of nitrate of silver, gallic acid, and glacial 
 acetic acid; that, under these circumstances, the iodide 
 of silver, which in its former condition remained, so 
 far as appearance is concerned, perfectly unaffected by 
 light, is, after being so treated, almost immediately 
 impressed with the figure of any object presented 
 to it in the camera. In the usual collodion process, 
 and that described in the last chapter, analogous 
 changes are produced, not in the camera, but by 
 subsequent treatment after removal from that in¬ 
 strument. 
 
 Major Russell, whose researches on the dry pro¬ 
 cesses of photography are so highly and deservedly 
 esteemed, was, it appears, in the habit, some time ago, 
 of finishing the washing of his plates with a weak 
 solution of gallic acid; and from a consideration of the 
 analogy, in reference to chemical composition, which 
 c 
 
34 
 
 exists between gallic acid and tannin or tannic acid, 
 be was induced to substitute the latter. 
 
 It would lead us into chemical reasoning, unwelcome 
 to the general photographic reader, if, by the intro¬ 
 duction of chemical formulas, we were to compare 
 these two substances. It will be sufficient to state 
 that we can in a most satisfactory manner trace their 
 analogy, and refer the formation of gallic acid from 
 tannin to the absorption of oxygen gas; and indeed, 
 it is a well-known fact, that an infusion of gall-nuts, 
 after long exposure to atmospheric air, becomes, with 
 other changes, loaded with gallic acid. Our purpose, 
 so far as description is concerned, will, however, be 
 sufficiently met by recognising tannic acid as a highly 
 metamorphic body, and that the result of the molecu¬ 
 lar changes of its constituent parts is the production 
 of a substance specially used for the eliciting of the 
 latent image impressed by light on the iodide of silver 
 and presenting it to the eye. With this material then, 
 Major ftussell coated a collodion plate, having pre¬ 
 viously carefully washed off the free nitrate of silver; 
 for it must be observed, that a solution of tannic acid,, 
 brought into contact with a solution of nitrate of silver, 
 becomes instantly decomposed, and requires the pre¬ 
 sence of acetic or some other acid to retard its action. 
 The plate, when exposed in the camera, and subse¬ 
 quently treated with developing agents, afforded an 
 image of remarkable beauty, and meeting many of the 
 most important requirements of the photographer: 
 a practical difficulty, however, presented itself in the 
 mechanical nature of the film. The tannin acts upon 
 the collodion in such a manner that it contracts in 
 
35 
 
 drying, and, when again moistened, separates itself 
 from the glass. For the means by which this diffi¬ 
 culty was most successfully overcome, and the descrip¬ 
 tion of the details of the process, the reader is referred 
 to Major Russell’s valuable work on this subject, the 
 utility of which extends to modes of manipulation and 
 hints of great practical value in relation to photo¬ 
 graphical operations generally; and this brings us to 
 the consideration of another method, which commends 
 itself to the tourist, as one of greater rapidity than 
 that described in the last Chapter. 
 
 Process II.—Any person who has employed the 
 malt infusion as a preservative must have remarked 
 its gummy feel. Indeed, this property in the process, 
 as recommended by Mr. Macnair, in which the infusion 
 is dried on the plate, is inconvenient on account of its 
 retaining the dust, which unavoidably floats in the 
 operating room, with great tenacity, occasioning, in 
 the future processes, transparent spots in the high 
 lights. But, on the other hand, this property is of 
 advantage in the plan proposed by the writer—in fact, 
 when first applied it causes the collodion film to ad¬ 
 here with great firmness to the glass, thus rendering 
 it capable of bearing somewhat rough after-treatment 
 with impunity whilst being washed off. When this 
 purpose has been effected, the plate can be dried 
 without risk from dust. Now, it occurred to the 
 writer that this property might be still further utilised, 
 and the process much improved, by the addition of 
 tannin to the malt solution; and, early in the year 
 1861, an experimental inquiry was instituted on the 
 subject. 
 
1. On adding a solution of tannin to the infusion of 
 malt, as before described, a copious fiocculent precipi¬ 
 tate was thrown down. 
 
 2. The supernatant fluid retained a milky, emulsive 
 appearance, which could not be cleaned by filtration. 
 The principal part, if not the whole, of the organic 
 matter contained in the malt infusion seemed to have 
 been precipitated; and, although the fluid still retained 
 just a trace of sweetness, with the smell of the volatile 
 oil of the malt, still, little hope was entertained that 
 any other results would be obtained from its use as a 
 preservative than from a simple solution of tannin; 
 but, on evaporating a portion of each solution on a 
 separate glass plate, it was observed— 
 
 3. That a portion of the malt material still remained, 
 rendering the characters of the dried extract palpably 
 different from that of dried tannin. It was, therefore, 
 determined to proceed, and in the following manner:— 
 
 Five grains of tannic acid were dissolved in an 
 ounce of malt infusion, prepared as at page 26, but 
 without the addition of alcohol. After the precipitate 
 had subsided, the fluid portion was decanted and 
 filtered through coarse paper. It was then used as a 
 preservative fluid, with precautions, especially in 
 reference to washing, as in Process I.; and plates thus 
 prepared were exposed as usual, with the following 
 most discouraging result, as extracted from the writer’s 
 note-book:— 
 
 “April KM, 1861, section 137.—The tannin solution 
 spoiled my plates; they developed all over. At any 
 rate, in this process it must be used with far greater 
 caution.” And, had the research been closed at this 
 
37 
 
 point, a most valuable resource to the tourist and dry- 
 plate photographer would not have been thus intro¬ 
 duced. The note states that the plates developed all 
 over. Of course they did: they were over-exposed on 
 a lovely April morning, about 11 a.m., for the same 
 time as used in Process I., and treated, as regards de¬ 
 velopment, in a manner appropriate to that process, 
 which will be described in Chap. IY. Many other 
 trials followed, with various treatment as to time, 
 &c., and, on referring again to the notes, an entry is 
 found:— 
 
 “ April 15^, section 140.—Since writing section 137, a 
 considerable number of experiments have been made 
 with the malt preservative and tannin conjointly. The 
 following plan answers admirably:— 
 
 “ 1. Having prepared malt infusion and strained it, 
 add one-third bulk of alcohol. Leave to deposit, and 
 filter. 
 
 “ 2. Just before using, add an equal bulk of solution 
 of tannin in water, five grains to the ounce, and again 
 filter.” 
 
 Other substances were now tried, which are only 
 recorded to save others from working in a wrong 
 direction, thus— 
 
 “May ls£, section 150.—Instead of tannin, sulphate of 
 iron was used with the malt infusion, and the result 
 was excellent; ” but 
 
 “ May 2nd , section 151.—Putting together all the 
 results I have obtained, the most sensitive and con¬ 
 venient plan is the malt infusion with tannin.” And 
 again: section 153, same date.—“ A negative I took this 
 afternoon, at 5.30, fully proved the superiority of the 
 
38 
 
 malt tannin over every other preservative process I 
 have tried.” 
 
 The writer’s note-book continues to register results 
 from time to time, and negatives, still produceable, 
 began to accumulate—failures as well as others — 
 which gave a clue to systematising the plan in such a 
 way as to prepare it for more general adoption; not, 
 however, without many perplexing misadventures. 
 Thus, it would be found that plates, prepared at the 
 interval only of a few days, with every precaution, 
 varied greatly in sensitiveness. That on some days, 
 dull and cloudy, better results were obtained in a 
 shorter time than on days wdiich promised more 
 energetic actinism; and especially that a strange per¬ 
 versity in many cases was observed between the wet 
 and dry process. Thus, on some occasions twice the 
 usual exposure was required in the dry process, whilst 
 no perceptible increase of exposure was needed in the 
 .wet process, with many other anomalies, the causes of 
 some of which have been ascertained, and will be 
 explained in Chapter IV., whilst others still remain as 
 objects of inquiry; and the extracts from the note¬ 
 book, on this part of the subject, will conclude with 
 a satisfactory entry relative to the keeping properties 
 of the plates, [which ample, subsequent experience has 
 fully confirmed. 
 
 u Nov. Znd, 1861, section 182.—Obtained an excellent 
 negative to-day, from a plate preserved in the middle 
 of September. After exposure for two minutes, sun¬ 
 shine, 12 a.m., it was dipped in a bath of aceto-nitrate 
 of silver for three minutes, and developed with gallic 
 acid as usual; afterwards treated with pyrogallic acid 
 and nitrate of silver.” 
 
39 
 
 The process just described was employed for the 
 next spring and summer. As might be expected 
 many disappointments occurred, most of which, re¬ 
 lating to the preparation of the plates, may be avoided 
 by adhering to the directions in the next chapter, 
 which will be principally devoted to manipulatory de¬ 
 tails. Others depended on meteorological conditions, 
 which will require much observation and study before 
 the causes are clearly ascertained. This, indeed, 
 seems at present to be the weak point in the dry pro¬ 
 cesses; the time employed by the wet process in 
 placing the plate in a condition to be acted upon by 
 developers is so short, that many disturbing forces, 
 which seem to operate on the dry plate, have no time 
 to act,—and this seems to be especially the case at 
 certain seasons of the year, and even times of the 
 day, which are by most persons considered the most 
 favourable for photographic operations. The best 
 negatives produced, as proofs of this assertion, were 
 taken in the late autumn and early spring months, 
 or in summer, from six to nine a.m.; and, impressed 
 wutli the considerations above stated, a variety of 
 experiments were made to discover a process still 
 more nearly approximating the usual collodion plan. 
 Of course, the practical advantages of a more rapid 
 dry method, for taking groups and moving objects, 
 were kept in view; but still, the principal aim was to 
 get rid of presumptive disturbing forces, which seemed 
 to operate upon pictures full of detail and, in other 
 respects, unobjectionable, rendering them incapable of 
 such an amount of development as is found necessary 
 for good printing. Another most important point was 
 
40 
 
 not lost sight of,—the opportunity of diminishing the 
 size of the stop in proportion to the sensibility of the 
 plate. 
 
 The result of the numerous and varied experiments- 
 on this subject will be summed up in the description 
 of— 
 
 Process III.—The film then, has, by the former 
 methods, been brought into a condition much more 
 favourable to the action of light than any of the usual 
 processes, whilst, at the same time, its mechanical 
 properties are such as to allow it to bear subsequent 
 treatment without risk of losing it; and, after many 
 experiments, a substance presented itself, which not 
 only promoted sensitiveness in a remarkable degree, 
 but came distinctly under the category of the theo¬ 
 retical considerations registered at page 20, a sub¬ 
 stance, in fact, which is not only produced from 
 others by changes easily effected, but is itself so nicely 
 balanced as to the* forces which keep its molecules in 
 a state of aggregation, that these can be disturbed 
 and assume new forms by apparently trifling causes. 
 
 Glycerine, for instance, is a body held together by 
 slight affinities; oxalic acid is another such body; and 
 by placing these two in contact and applying heat, we 
 produce a third body—formic acid, which has recently 
 again come into prominent notice as a photographic 
 agent. Glycerine, moreover, has the property of re¬ 
 ducing metals from their solutions; thus, when boiled 
 with a solution of sulphate of copper, the metal 
 itself is thrown down. On adding glycerine, then, 
 to the preservative fluid of infusion of malt and 
 tannin, a sensitised and washed collodion plate, 
 
41 
 
 when coated with the mixture, again washed and 
 dried, was exposed in the camera. The time of year 
 (Nov. and Dec., 1862) was certainly not that usually 
 chosen for testing the capabilities of dry plates: 
 the results wer%, however, favourable, as good nega¬ 
 tives were produced with two minutes’ exposure, not 
 longer than had frequently been given with plates 
 prepared as in the other dry processes in the height 
 of summer; and it now remained to determine the 
 most favourable method of applying the process as 
 thus modified. 
 
 In the first place, however, it was necessary to 
 decide which of the two—the malt infusion or the 
 tannin in conjunction with the glycerine—was most 
 effective, or whether all three were necessary: to an 
 ounce, therefore, of the infusion of malt, was added a 
 fluid drachm of glycerine. The result was far less 
 sensitive than of the three conjoined—in fact, did not 
 appear more so than the malt infusion alone. The 
 next coating was with tannin, five grains; water, half- 
 an-ounce ; glycerine, thirty minims; the plate seemed 
 quite as sensitive as with the original solution, indeed, 
 with other precautions as to the preliminary prepara¬ 
 tion of the plate, negatives were produced between 
 Dec., 1862, and this month, May, 1863, some of them 
 with hard frost and cold winds, in from thirty to fifty 
 seconds, and many of the best in cloudy weather. 
 Other avocations, and preparing these notes for press, 
 in hopes that they may be advantageous to tourists in 
 the approaching season, have prevented the exposure 
 of many plates for the last week or two; and those 
 which have been exposed, from some cause which has 
 
42 
 
 not as yet been investigated, are not so sensitive as 
 those used in the winter and early spring, and fifty 
 •seconds with the same glasses and diaphragms have 
 not been found too long for exposure : most probably, 
 however, either the bath or preservative fluid will be 
 found deteriorated. 
 
 We have now, therefore, arrived at a stage of our 
 investigation which shows that the previous processes 
 may be much simplified, inasmuch as the malt infusion 
 may be dispensed with altogether; though, in certain 
 cases which will shortly be pointed out, it may still be 
 used with advantage, and we now proceed to give the 
 formulae which were decided upon, merely remarking 
 that the quantity of tannic acid employed is much 
 larger than in the former process, as will appear in 
 the sequel. 
 
 The following quotation is from the notes entered at 
 the time:— 
 
 “Dec. 4th, 1862, section 211.—The preservative solu¬ 
 tion for the tanno-glycerine process is thus prepared:— 
 Solution A. Tannic acid.30 grains. 
 
 Water. 1 ounce. 
 
 Glacial acetic acid 5 drops. 
 
 Solution B. Glycerine . 1 drachm. 
 
 Solution A. 2 drachms. 
 
 Water. 5 „ 
 
 which latter is poured on and off the plate in the usual 
 manner adopted at this stage.” The addition of acetic 
 acid was made in consequence of slight fogginess 
 observed on certain portions of the plate during 
 development, and it certainly remedied the evil; but 
 the bath was in fault, as it gave foggy results with 
 
43 
 
 the wet process. A few drops, however, of acetic 
 acid brought it back to working order, and here it 
 may be remarked that in these processes the addition 
 of a certain quantity of acetic acid, determined by 
 experiment, not only does not produce insensitiveness, 
 but actually forwards the progress of development, 
 and for this reason:—the slightest deposit of silver, not 
 elicited by the action of light, but by a general 
 decomposition of the developing fluid, will, as the 
 development proceeds, injure if not totally destroy 
 the plate, and immediately as such deposit, either 
 above or under the film, takes place, it is useless to 
 proceed with the future manipulation. Major Russell 
 has mentioned this with reference to the tannin pro¬ 
 cess, but want of time prevents the writer referring to 
 his work for the quotation. 
 
 What may be expected in taking interiors upon a 
 plate treated with this preservative will be best seen 
 from an extract. 
 
 “ Dec. 5th, 1862, section 213.—Exposed a stereo.-plate 
 in the drawing-room at noon, the day exceedingly 
 cloudy and dull—easterly wind: one side exposed for 
 ten, the other twenty minutes. Dallmeyers stereo¬ 
 scopic double-arrangement, diaphragm No. 4; both 
 came out after long development—nine hours.” 
 
 The development was by a favourite slow process, 
 which will be given in its proper place, and produces 
 extremely sharp negatives, as it contains but a very 
 small quantity of nitrate of silver, which is deposited 
 with amazing regularity. That a prepared plate can 
 endure so much soaking without injury is a great 
 recommendation; it must, however, be mentioned that 
 
44 
 
 the collodion used was admirably adapted to the pur¬ 
 pose : by the addition of the infusion of malt the film 
 is rendered still safer, but of this more hereafter. 
 
 The slow developer was used merely as an experi¬ 
 ment; others, far more rapid in action should, of course, 
 be employed under similar circumstances. And now, 
 to bring the descriptive portion of these processes to 
 a conclusion, another will be mentioned which pro¬ 
 mises very rapid results, and is now under experiment. 
 It, however, requires great precaution, as the details 
 of its preparation will evidently suggest. 
 
 Process IY.—The tannin and glycerine are used as 
 before, with the addition of ten minims of formic acid 
 to each ounce of the preservative solution, and when 
 well mixed, which, of course, must be at the time of 
 using, ten minims of solution of nitrate of silver, 
 strength twenty grains to the ounce; the quantity of 
 the two last fluids maybe increased to thirty minims of 
 each; but most extraordinary care must be taken 
 thoroughly to wash the plates. Let it also be observed 
 that formic acid of the strength used by the writer, 
 which is the strongest and purest he can obtain, has a 
 great tendency to loosen the film bodily from the plate ; 
 in certain kinds of collodion, this has no doubt been 
 observed with glacial acetic acid 3 and the writer has, in 
 ancient times, made use of this device for the pur¬ 
 pose of transferring the collodion film; and, indeed, for 
 mounting microscopic specimens this plan is valuable. 
 Take, for instance, the very beautiful ciliary processes 
 of the balanasporcatus —the common rock barnacle of our 
 coasts—and arrange them on a small plate of glass; 
 with careful washing all the salt water and its solu- 
 
45 
 
 tions may be removed; the whole should be placed in 
 a slow oven or under the receiver of the air pump to dry, 
 and then a few drops of moderately thin uniodised and 
 freshly-prepared collodion poured over the specimen. 
 This, when dry, may be floated off the plate into a 
 vessel of clean water, with four or five drops of glacial 
 acetic acid, and when sufficiently washed and dried, be 
 appropriately trimmed and mounted for the microscope. 
 The calcareous frame-work of the organs is not injured, 
 as' it is inclosed in a coating of collodion, and the con¬ 
 tact of the acetic acid with this is so short that no 
 action can take place other than that pointed out. 
 Hundreds of other objects adapted to similar treatment 
 will occur to the microscopist. 
 
 The plates, then, prepared by this process have been 
 used by the writer with no longer interval than a day 
 between their preparation and exposure; indeed the 
 suggestion only occurred to him a few days ago; they 
 will, however, thus used, give excellent results and 
 need not be developed for a similar interval after 
 exposure. 
 
 It now remains to explain the manipulatory pre¬ 
 cautions necessary for the successful working out of 
 these several methods, and a comparison oi the special 
 properties and advantages of each in reference to the 
 circumstances under which they may be respectively 
 employed. 
 
CHAPTER IV. 
 
 INTRODUCTION TO MANIPULATORY DETAILS-HINTS TO TOURISTS 
 
 IN THE POSITION OF THE WRITER AS AN AMATEUR-SELECTION 
 
 OF GLASS FOR PLATES-CLEANING-COATING WITH COLLODION- 
 
 KIND OF COLLODION ADAPTED TO THESE PROCESSES, WITH FOR¬ 
 MULA FOR PREPARATION-ACTION OF AIR AND LIGHT ON OXI¬ 
 DISED COTTON-NITRATE OF SILVER BATH-DETERIORATION 
 
 FROM USE-CORRECTION-WASHING PLATE FROM SURFACE- 
 
 NITRATE OF SILVER—APPLICATION OF PRESERVATIVE FLUID- 
 
 DRYING PLATES-SUGGESTIONS ON SUITABLE CAMERAS—SIMPLE 
 
 METHOD OF FINDING STEREOSCOPIC ANGLE-TIME OF EXPOSURE 
 
 -DEVELOPMENT-SLOW DEVELOPMENT, WITH ITS SPECIAL 
 
 ADVANTAGES-MORE RAPID METHODS—ALLUSION TO FUMING 
 
 WITH AMMONIA—FORMIC ACID—TREATMENT OF FILM UNDER 
 PECULIAR CIRCUMSTANCES-INCIDENTAL REMARKS. 
 
 In entering upon the manipulatory details of the pro¬ 
 cesses described in the previous chapters, it is hardly 
 necessary to observe that some previous knowledge of 
 photography is assumed: that the reader is practi¬ 
 cally acquainted with the usual wet collodion process, 
 not merely as a convenient method for taking por¬ 
 traits, for this, perhaps, is the least important use to 
 which photography can be applied,—certainly so in 
 the conviction of those who are able to appreciate the 
 importance of its application to a vast variety of other 
 purposes; to the arts and sciences; to the faithful 
 record of passing events, in a manner so absolutely 
 representative of the scenes of life actually occurring 
 at specific periods, as to leave no room for the poetry 
 
47 
 
 of tradition or the bias of the historian; to the re¬ 
 quirements of the naturalist, as affording a facsimile of 
 deviations from normal and familiar structure, in cases 
 when representations, to be made truthfully, must be 
 made on the spot, with a rapidity and correctness of 
 detail which would foil the powers of the most facile 
 draughtsman, and that not merely in plane surface, 
 but, by means of the stereoscope, in model relief; 
 to the art student, as saving him cost and trouble, fill¬ 
 ing his port-folio with correct representations of types 
 of form, in a time far shorter than could be done by 
 ordinary manual labour; to the tourist for health or 
 recreation, as furnishing him with reminiscences of 
 nature’s beauties, not only as a future solace to himself, 
 but, with proper description, interesting and instructing 
 those to whom circumstances have denied the enjoy¬ 
 ment of travel. It is further assumed, that some ex¬ 
 perience has been acquired in one or other of the 
 various dry processes already in use; and, should this 
 not be the case, the reader is earnestly recommended 
 faithfully to work out Major Russell’s tannin process, 
 following his written instructions implicitly; for, having 
 done so, no difficulty whatever will be felt in prac¬ 
 tising the methods described in this pamphlet: he will, 
 in fact, walk over the course ; and as the readers prin¬ 
 cipally kept in view are those who—purposing to em¬ 
 ploy photography in a manner subsidiary to its higher 
 purposes, as above hinted at—have neither leisure nor 
 opportunity to practise it except on occasions, a few 
 general hints from one placed in the same position 
 with themselves may not be considered unworthy of 
 regard. 
 
48 
 
 The first of these is to enter upon photographic 
 operations in a systematic manner and with a definite 
 plan. No one would think of arriving at any excel¬ 
 lence in sketching by at once attempting to take a 
 landscape, wdthout the slightest knowledge of per¬ 
 spective or the capability of drawing a perpendicular 
 line; and yet this is an absurdity more frequently 
 than not practised in photography, and is, no doubt, 
 the main cause of much of the disappointment which 
 many have experienced. There are certainly difficul¬ 
 ties in the art, especially in its more pretentious de¬ 
 partments, which would baffle any but those who make 
 it a daily practice,—nor do these always escape ; but 
 there is no reason why any sensible person, with an ordi¬ 
 nary camera, cheap glass, and the appropriate chemicals, 
 should not at any time, with certainty, be able to take 
 a view from nature. Commencing with card portraits 
 is, of all other plans, beginning at the wrong end for 
 the tourist. Consider the very different conditions of 
 the two cases. The carte-de-visite artist is engaged in 
 taking, day by day, objects of a precisely similar 
 character, many of them identical and fixed objects; 
 the focus may be considered as constant, at least the 
 variations are extremely slight, and the subsequent 
 operations are carried on in an unvarying, mechanical 
 routine. The writer, in fact, cannot view the portrait- 
 gallery in any other light than as a miniature manu¬ 
 factory. The tourist, on the contrary, is in a totally 
 different position: with him every new object presents 
 a fresh problem; arrangements must be altered at 
 every move in every part of the apparatus he carries 
 with him; in addition to this, his mind must be as 
 
49 
 
 ulert as liis body; and woe to his prospects if forgetful¬ 
 ness or diverted attention cause him for a moment to 
 overlook the many little essential points and precautions 
 which ensure success: in fact, the tourist-photographer 
 must of necessity be a sharp man. 
 
 In the next place, let the importance be urged of 
 keeping to one plan, until its practice has become easy 
 and familiar; should it be desirable to resort to others, 
 this at least will be employed with confidence, and it 
 is astonishing, in practice, how this confidence transfers 
 itself, as it were, to any new method; the very convic¬ 
 tion that one view at least is safe, so far as circum¬ 
 stances admit, enables the operator to employ any less 
 tried method without anxiety. 
 
 And, lastly, plates that fail from any unknown cause 
 should be kept; for, in this art as well as in the art of 
 living, generally failures, if properly used, are exceed¬ 
 ingly valuable records, and teach much more to the 
 conscientious student than uniform success. 
 
 To begin, then, with the materials required; and first 
 as to the glass plates. Here it is presumed that, for 
 ordinary tourist purposes, the kind known as best 
 flatted-crown will be selected: they are much lighter 
 than those of patent plate; they seem to be harder, 
 and not, therefore, running so much risk of being 
 scratched—they are also considerably less expensive ; 
 but, as a set off, they are not so fiat as necessary for 
 some purposes; the writer believes, however, that on 
 an average, nine out of each dozen may be selected 
 quite flat enough for ordinary use, and some even for 
 printing on glass by superposition. Of course, in paper 
 printing a little curvature is of no consequence, as by 
 
 D 
 
50 
 
 placing three or four folds of black cotton velvet over 
 the paper, the pressure in the printing-frame will be so 
 evenly distributed as to occasion no great risk: this 
 curvature may even be utilised by coating the concave 
 side, and thus in some degree correcting spherical 
 aberration. Of course, such plates could not be sent 
 out to print, as they could not be treated with such 
 tender consideration as is compatible with their 
 safety. Where great precision and durability are essen¬ 
 tial, the patent plates must be used, but their weight 
 is so much greater, alluding, of course, to the thick 
 plates, that the tourist will probably confine their use 
 to objects of special interest. 
 
 Having decided upon the plates, the next important 
 object is to clean them thoroughly,—for as sent out 
 from the manufacturer, or even neatly packed from 
 the photographic warehouse, they are notin a condition 
 to use; for the mere handling is sufficient to spoil 
 results The secretion from the pores of the skin of 
 the most cleanly hand, when in contact with a salt of 
 silver and exposed to light, rapidly reduces the silver, 
 as most have experienced in impressions on albumen- 
 ised paper; and, perhaps, one of these days the salts 
 contained in the fluid of perspiration may be used with 
 success for the salting of paper,—the plates then must 
 be thoroughly cleaned, and an excellent plan is recom¬ 
 mended by Major Russell, who substitutes a solution of 
 iodine, in iodide of potassium, for nitric acid. The 
 plates are to be roughed on the edges by means of a 
 file; and it will be at once seen how easy it is, under 
 such circumstances, for a minute portion of nitric acid 
 to remain in the cavities, which, however insignificant 
 
51 
 
 on one plate, produce a most material effect on the 
 bath after three or four dozen plates have been sensi¬ 
 tised: for it is well known to practical men, that 
 keeping the silver bath in a delicate state of balance 
 between fogging and insensitiveness, is one of the 
 most important problems in the art, no less applicable 
 to dry than to wet plates. A simple and cleanly plan 
 is adopted by the writer:—A potatoe, having been 
 well washed, is cut in half, and the peel pared off, with 
 a clean knife, for a quarter of an inch round the cut 
 edge; the original cut surface is then slightly scooped 
 out, so as to retain any powder made into a paste with 
 a fluid. Now, in many cases, mechanical means are 
 required to remove impurities, and fine tripoli is gener¬ 
 ally used for this purpose, subject to the disadvantage, 
 however, that with every precaution, a portion, less 
 finely levigated, may intrude and scratch our plate. 
 Now we are acquainted with many minute crystals, but 
 slightly soluble in water, which are too soft to scratch 
 glass, and yet sufficiently hard for cleansing purposes; 
 and, from several others, the writer has selected the 
 bi-tartrate of potash (common cream of tartar), for this 
 purpose. Having filled up the hollow in the potatoe 
 section with this salt, a few drops of the iodine solu¬ 
 tion are poured on the plate, and rubbed over the whole 
 surface. It is obvious that this can be done without 
 any risk of staining the fingers, an object of no small 
 importance to lady photographers; an apple, of course, 
 answers the same purpose, and the malic acid assists 
 the operation: oranges and lemons are too yielding for 
 the amount of friction desirable. The plate is now to 
 be well washed in several waters, drained in a colander, 
 
52 
 
 wiped with a clean cloth, free from soap, and, at last, 
 rubbed with a wash leather kept for the purpose, which 
 has been well washed in soda. No pains should be 
 spared in cleaning the plate, when it should be placed 
 in the grooved box until required. 
 
 The next process is coating with collodion, of which 
 the appropriate kind will presently be described; and 
 even here some precaution is necessary. Many who 
 have not practised this department of photography 
 imagine, that, on account of its comparative slowness, 
 much greater liberties may be used with the plate than 
 in the usual wet process, whilst directly the contrary 
 is the fact. Certain disturbing forces, which, from the 
 shortness of their duration, hardly operate on the one, 
 produce a fatal influence on the other,—thus, in sup¬ 
 porting the plate for the purpose of coating it by means 
 of an ordinary pneumatic holder, in the wet process 
 the plate may generally be removed from the holder, 
 plunged in the bath without further precaution, ex¬ 
 posed, and developed, the whole of the operations being 
 completed in a few minutes; but, in the slower process 
 with dry plates, if the back of the plate be not care¬ 
 fully wiped after coating with collodion, the ring of the 
 holder is almost certain to be impressed in the future 
 negative. It must be remembered that, during the 
 evaporation of the ether from the coated surface, 
 intense cold is produced on every part of the back of 
 the plate not shielded by the holder; dew, in fact, is 
 condensed upon it,—and if the holder be not rapidly 
 removed, and the temperature equalised by wiping the 
 plate, the negative will in all probability be lost. The 
 same result must be endangered still more by the 
 
53 
 
 practice of supporting the plate on the tips of the 
 fingers of the left hand, on account of their warmth— 
 indeed, the accident alluded to sometimes befalls the 
 operator, even in the wet process. 
 
 As to the collodion adapted to the processes des¬ 
 cribed in this pamphlet, the writer has carefully 
 worked with preparations from almost all the renowned 
 makers, and finds that they may all be used with suc¬ 
 cess, specially excepting those which are devoted ex¬ 
 clusively to iron developers, apparently from their con¬ 
 taining a large quantity of bromides; and this is con¬ 
 trary to the results of bromides in excess, as applied to 
 Major Russell’s process, and described by him in a recent 
 number of The British Journal of Photography. 
 These salts do indeed give a rapid image, full of detail; 
 but by no device which the writer has tried can he 
 bring the negatives up to the amount of actinic resis¬ 
 tance requisite for printing. Some collodions are made 
 especially for the dry processes, and called powdery 
 collodions, but the more homogeneous films are as safe, 
 and indeed better, for a certain class of negatives, 
 those which are intended for enlarging in the camera. 
 By using the precautions to be hereafter mentioned, no 
 danger need be entertained of the film leaving the 
 glass, with ordinary care, whilst it bears less iodide, 
 more ether, and lies very close on the plate, giving 
 clean negatives, with distant objects beautifully defined. 
 Of course all collodions which are crapy, and make 
 the plate appear as if scratched with the hatchings of 
 a graver’s tool, are unfit for the purpose and must be 
 rejected. Few amateurs would wish to prepare their 
 own collodion, but it is a rule wfith those who under- 
 
54 
 
 take researches to make everything possible them¬ 
 selves, and the following formula may be depended 
 upon:—Good cotton, long fibred andclean, is plunged in¬ 
 to a mixture of three parts, by measure, of sulphuric acid, 
 which must be of full strength, and one part of strong 
 nitric acid, which will generally be found not to exceed 
 the sp. gr. ofl-38 to 1/40, having previously stirred these 
 with a glass rod ; no artificial heat must be applied nor 
 must more cotton be dipped than the fluid can well cover. 
 After gently pressing the cotton down repeatedly, so 
 that the mixed acids may permeate every fibre of cot¬ 
 ton, the vessel is to be covered with a glass plate and left 
 for fully a quarter of an hour; after again stirring 
 with the glass rod, the fluid should be poured off and 
 pressed out; having previously mixed a fresh quantity of 
 acids, in equal proportions of sulphuric and nitric acids, 
 the cotton is to be re-introduced, moved about gently 
 for a minute, and, after covering the vessel as before, 
 left to digest for ten minutes ; the acids are then 
 poured off and pressed out, the cotton thrown into a 
 large vessel of water and moved about, frequently 
 changing the water, until they are so far removed that 
 the remainder of the water can be pressed out in a 
 cloth. The cotton is then soaked in a solution of 
 acetate of soda, ten grains to the ounce, thoroughly 
 •washed in many changes of water, pressed, dried, and 
 carefully pulled out. Four grains of this cotton are 
 sufficient for an ounce of the usual mixture of alcohol 
 and ether, and, iodised with three grains of iodide of 
 sodium and one grain of bromide of cadmium, this is a 
 very simple form, keeps well, and improves by keeping 
 within ordinary limits. Those who wish to make their- 
 
55 
 
 own collodion, without the annoyance of preparing the 
 cotton, may obtain it of excellent quality from respect¬ 
 able houses; but it should be remembered that oxidised 
 cotton soon deteriorates and becomes acid if exposed 
 to air and light, in fact, oxalic and nitrous acids are 
 formed, the slightest trace of either of which will ren¬ 
 der the collodion unfit for use, and, if the cotton has 
 been kept for some time, it should always be re-washed 
 in solution of acetate of soda, with the other pre¬ 
 cautions stated, before using it for collodion. The 
 writer has become acquainted with cases in which 
 great disappointment and pecuniary loss have resulted 
 from this cause. 
 
 We now suppose the plate to be coated, and ready 
 to dip into the bath of nitrate of silver, which is thus 
 composed for ten ounces:— L $r l 
 
 A. 
 
 Re-crystallised nitrate of silver 
 
 320 grains. 
 
 
 Distilled water. 
 
 5 ounces. 
 
 B. 
 
 Caustic potash (avoid ammonia) 
 
 2 grains. 
 
 
 Distilled water. 
 
 1 ounce. 
 
 Mix these, and, when agitated, allow the precipitate to 
 
 subside, and filter; fill up to nine ounces and add 
 acetate of soda,[previously dissolved in an ounce of 
 water] three grains with five minims of glacial acetic 
 acid.y^The bath is now ready for use, and should be 
 tested for action with a wet collodion plate, develop¬ 
 ing with pyrogallic acid. If foggy, more acetic acid 
 should be added, drop by drop, until the bath works 
 clear; but the writer has always found the above pro¬ 
 portions give good results. It will be observed that 
 the bath is not, as usual, saturated with iodide of sil¬ 
 ver : the first plate may suffer a little if the weather 
 
56 
 
 be very warm, but it is simpler and safer, for reasons, 
 which will presently be stated, to leave it thus. 
 
 After a certain number of plates has been prepared, 
 say three dozen, more or less, change will have taken 
 place in the action of the bath: it will not act so 
 readily, and, if the collodion contain an undue propor¬ 
 tion of bromides, the character of the negatives will be 
 altered; they will still indeed be full of detail, but will 
 not readily, if at all, admit of such an accumulation of 
 silver in development as is necessary to produce a good 
 negative; the colour of the negative will not be the 
 same as before, and will be much more permeable to 
 the actinic rays. The bath then must be corrected, or 
 a new one formed. The writer would recommend 
 keeping two baths, so that one can be used whilst the 
 other is repairing, which is easily accomplished as 
 follows:— 
 
 Pour the bath into a Florence flask, or such like 
 vessel, and boil it in a water bath, or, in less technical 
 terms, in a saucepanful of water. By this means, the 
 volatile matters, alcohol, ether, and principal excess of 
 acetic acid are removed; add the solution of caustic 
 potash, as before, until a brown precipitate of oxide of 
 silver is formed, agitate well, expose to the sun for an 
 hour or two, filter, add fifty grains of nitrate of silver 
 and a few drops of acetic acid, when the batli will be 
 ready for use immediately as the nitrate of silver is 
 dissolved. A larger quantity of acetate of soda may 
 be added at first, but it is not advisable, as the acetate 
 of silver is sure to accumulate, and, after the bath has^ 
 been thus corrected four times, from this and other 
 causes, it will be better to discontinue its use; no waste 
 
57 
 
 whatever need be made, as it is only necessary to 
 throw down the chloride of silver with a solution of 
 common salt; the curdy precipitate is repeatedly 
 washed with common water, collected on a thick calico 
 strainer, the fluid squeezed out, and the whole dried in 
 an oven, when the chloride of silver may be collected: 
 and sent to a respectable assayer, who will give the full 
 value of it, or send back re-crystallised nitrate of 
 silver in exchange. Those who are unaccustomed to 
 chemical operations will find this a far more economical 
 plan than re-forming the nitrate of silver, which, on the 
 small scale, can only be done with considerable loss of 
 material. 
 
 Having then sensitised the plate, by allowing it to 
 remain five minutes at least in the bath, it is trans¬ 
 ferred into another containing distilled water, or, at any 
 rate, soft water which has been boiled (if the latter, 
 with the addition of five drops of glacial acetic acid to 
 each ten ounces), and left to soak for some minutes, 
 until the oily appearance of the film—familiar to- 
 everyone—ceases, and then placed in another dish of 
 water for a few minutes longer: the water in the 
 bath may be used for some dozens of plates, to collect 
 the excess of nitrate of silver from the sensitising 
 bath, then reducing it to chloride as above stated*- 
 the water in the dish should be frequently replaced: a 
 gentle stream of water is now poured from a jug, and 
 the plate is ready for the preservativ e solution selected 
 from those described in the preceding Chapter. In the 
 tannin and some other processes, a small quantity of 
 chloride is recommended to be added to the water in 
 the dish; the writer does not advise this, as the pre- 
 
58 
 
 sence of chlorides is a fruitful source of wliat are known 
 as pinholes in the denser portions of the negative. 
 
 The preservative fluid then is poured into a clean 
 developing glass, in the proportion of one ounce for 
 every six plates, after which it should be replaced with 
 fresh fluid, as it becomes much diluted by use, and the 
 plate, if of stereoscopic size, being held at the upper 
 corners between the thumb and fore-finger of the left 
 hand, is to be covered with the fluid, beginning near 
 the top and chasing the surface water downwards, 
 allowing it to run into the developing glass, and repeat¬ 
 ing this action several times ; now reverse the plate, and 
 proceed in the same manner. It is essential, as before 
 stated, that the preservative solution should not merely 
 float on the film, it must penetrate it to be effective; 
 and the successful preparation of the plate depends 
 mainly upon the care with which this part of the pro¬ 
 cess is accomplished. The plate is now placed in a 
 dish of clean water, which will answer for two or three 
 dozen plates, and allowed to soak while others are 
 preparing. With a little system these operations may 
 be carried on in succession with considerable rapidity, 
 and a dozen plates can easily be prepared in an hour. 
 Nothing now remains but to pour a gentle stream of 
 water over the plate and place it, resting on one cor¬ 
 ner, on blotting paper to drain, the upper corner of the 
 plate being supported against any suitable fixture. 
 When the whole of the plates proposed to be prepared 
 have thus drained they may be placed inside a box, re¬ 
 clining against the sides, with the sensitive surfaces 
 upwards, and reilioved to a moderately-heated oven 
 until they are as hot as the hand can bear, and then, 
 
59 
 
 being finished, they should be stored away in the 
 grooved box for use. 
 
 It is hardly necessary to say that all these operations 
 should be carried on in a room to which not a ray of 
 actinic light has access. The plates are so sensitive 
 to diffused light, that, when used for printing trans¬ 
 parencies, a fraction of a second’s exposure to a north¬ 
 ern sky is abundant. They may also be printed by 
 gas-light, or, if it were not for the objectionable fumes, 
 by the light of inflamed phosphorus, which the writer 
 finds highly actinic. It seems equally unnecessary to 
 point out the prudence of testing the bath, each time 
 corrected, by means of a wet collodion plate, or, in 
 making a stock of plates from fresh quantities of pre¬ 
 servative fluid, to try one dry plate before proceeding 
 further: these precautions may give a little more 
 trouble, but this is amply compensated for by the 
 comparative certainty with which a tour will be en¬ 
 tered upon, and, indeed, the word trouble is unknown in 
 research. 
 
 We are now prepared to take a view, and assume 
 that the reader is fully acquainted with the ordinary 
 mode of doing so, and has had some previous practice 
 in the operation. The apparatus for the purpose is, of 
 course, the lightest that can be procured, compatible 
 with steadiness and the absolute exclusion of a ray of 
 light which does not enter through the lens. The 
 admirable specimens of work in this department afford 
 the tourist a wide scope for choice. It is probable, 
 however, that, if going a distance, he will select a 
 stereoscopic camera,—for, although the views may be 
 small, it is no great feat to enlarge a picture of three 
 
60 
 
 inches square to one of 12 X 10 inches or much larger 
 by the solar apparatus. 
 
 The writer has hitherto avoided all names in con¬ 
 nection with collodion or other business departments- 
 of photography, feeling such matters to be totally 
 without the scope of this pamphlet; he may, however* 
 be permitted to state, that he has found a small 
 stereoscopic camera, purchased from Messrs. Squire, 
 very portable and useful as a travelling companion, 
 with a few modifications, which may be adopted with 
 great advantage to ensure greater steadiness, a most 
 material point for the tourist who cannot always screen 
 himself from the wind. The two pieces of wood, 
 which are attached to the base of the camera alluded 
 to for determining the stereoscopic angle, are removed, 
 and the camera screwed on to a slip of well-seasoned, 
 mahogany, 4x1 inch, and half-an-inch thick, bevelled 
 off on both sides of one surface—the narrower surface 
 towards the camera. Another piece of wood, which 
 may be deal, twelve inches, long, three inches wide, 
 and an inch thick, is now provided with two thin 
 pieces of mahogany of the same thickness as the 
 former, each bevelled off on one side and screwed or 
 otherwise fastened on to the deal, with the bevelled 
 edges downwards, and in such a manner that they may 
 serve as accurate guides within which the portion 
 attached to the camera may slide, after the fashion of 
 a Wollaston’s sliding scale: the other side, having a 
 brass plate, with a screw hole tapped in, fastened on, 
 will furnish the means of its being attached to the 
 tripod stand. Suppose now the whole apparatus set 
 up for work; the camera is brought to the right sida 
 
61 
 
 of the table, and a view taken. It is then pushed 
 towards the left side three inches, which may be 
 marked for permanent use; the table, with all its 
 belongings, should now be very slightly rotated on 
 the stand for one quarter of an inch, measured from the 
 extremity of the table, and an excellent stereoscopic 
 effect will be produced for a lens with a focus of 3*75 
 inches. The amount of this rotation is not of much 
 consequence, provided it be not in excess, which would 
 produce exaggerated relief; if not rotated at all, the 
 object would still appear stereoscopic, though with 
 under relief; besides, in a double picture, taken with 
 the monocular camera, it is not necessary to cut the 
 paper, provided a given point in each picture does not 
 exceed 2J- or 2f inches in distance from its companion, 
 and this is ensured by the formula given. Again, this 
 contrivance is applicable to pictures of all sizes, pro¬ 
 posed to be taken stereoscopically: thus, for the sake 
 of round numbers, take four inches as the focus 
 adapted to the above distance, place on the slide a 
 camera of a larger size, fitted with a twelve-inch focus 
 lens, capable of taking a whole-plate picture ; now 
 4 : 3 :: 12 : 9 inches the distance through which the 
 camera will have to move for stereoscopic effect in 
 taking two pictures, the degree of rotation being th 
 same as before. This very simple subject of the 
 stereoscopic angle, as theoretically viewed, has been 
 much misunderstood, and many absurd instructions 
 given as to the distances required; but the reader will 
 not be disappointed in putting the above hints into 
 practice. Two excellent double slides were sent with 
 the camera, but they were found too delicately con- 
 
62 
 
 structed for brass binges, the screws not having 
 sufficient depth of substance to hold, and soft kid 
 leather -was substituted, a strip being fastened over 
 the whole length which connects the two sides of the 
 slide. The writer employs a still more simple camera 
 for twin lenses, which can be constructed in a short 
 time by any one, even on a journey, if necessary. 
 The material of which it is principally composed is 
 thick pasteboard, covered on the outside with black 
 holland, lined on the inside with black cotton velvet ; 
 the lenses, single view lenses of 4J inches focus, are 
 placed three inches apart, measuring from centres, the 
 flanges being screwed on to a mahogany slide, so 
 arranged that it can be moved in a vertical direction 
 for a full inch, thus giving an opportunity of varying 
 the position of the horizontal -line for different objects 
 or at different elevations; the frame in front is adapted 
 to the slides above mentioned. Both back and front 
 can be removed at pleasure, the pasteboard folded up, 
 and the most jealous douanier , meeting with the whole 
 in a traveller’s portmanteau, would scarcely recognise 
 the individual parts of a most useful and efficient binocu¬ 
 lar camera. The weight of stand, camera, slides, and all 
 the accompaniments necessary for a journey, is under 
 seven tbs.; indeed, it would not be easy to construct a 
 more convenient travelling companion; as the slides fit 
 both instruments,—the former one being arranged as a 
 monocular for double glasses,—the addition of weight 
 in travelling with both is not worthy of consideration. 
 The writer does not burden himself with a level, but, 
 as a substitute, on the portions of the ground glass 
 occupied by each picture, a line in pencil is drawn to' 
 
63 
 
 represent the horizon, and a vertical line to secure 
 perpendicularity. Two legs of the tripod being fixed, 
 it is easy, with the other, to obtain such a position that 
 the two pictures may assume precisely the same rela¬ 
 tive position and be truly level. Nothing further 
 remains than to elevate or depress the front slide, to 
 determine the horizontal line desirable; a compara¬ 
 tively unpractised eye will detect any deviation in 
 level; but, at the same time, when great precision is 
 required, such as for future measurement by scale, ad¬ 
 ditional precautions will be necessary. These details 
 arranged, it only remains to remove the focussing 
 slide, substitute one containing a prepared plate, and 
 expose. The time for exposure, with an ordinary ste¬ 
 reoscopic lens and stop one quarter inch in diameter, will 
 vary, in Process I., from one minute and a-half to two 
 minutes, according to the nature of the object and the 
 state of the atmosphere; in Process II., about one 
 minute; in Process III., thirty to forty seconds; in 
 Process IV., the time necessary has not yet been 
 determined, but about half that time will probably be 
 found sufficient. There are, of course, minimum 
 periods to which the operator would not confine him¬ 
 self, excepting where objects liable to move are to be 
 represented. 
 
 It must be borne in mind that the utmost precaution 
 is necessary in excluding the slightest admission of 
 light. Previously to undertaking each tour the camera 
 and slides ought to be thoroughly overhauled; and, 
 before taking a view, the whole camera, excepting 
 lens space, and slides should be covered with a black 
 cloth, the slides being opened under the cloth. The 
 
64 
 
 whole apparatus also, especially in windy weather, 
 should have the benefit of the shelter of an umbrella, 
 which will greatly assist in securing steadiness. 
 
 We now proceed to the important subject of deve¬ 
 lopment. By any process mentioned a picture can 
 scarcely fail of being impressed on the plate, and its 
 resulting in a good negative depends entirely on the 
 operator. Having then returned to the dark-room, or 
 its equivalent, the first step, with reference to the 
 plate, is to pour distilled, or, at any rate, water abso¬ 
 lutely free from chlorides or carbonates, over it, until 
 the film is thoroughly moistened. In travelling, it is 
 not always possible to obtain distilled water, but easy 
 to find a substitute by dropping a w T eak solution of nitrate 
 of silver into it until the fluid no longer becomes turbid. 
 Snow water has been recommended, but we must be 
 on our guard as carbonate of ammonia may be pre¬ 
 sent. The water of many mountain lakes is also pure, 
 but much will depend on the geological structure of 
 the surrounding country: we should, for instance, ex¬ 
 pect to find the water more free from metallic solutions 
 at Geneva than at Llanberis; in the processes, how¬ 
 ever, described in this pamphlet, more than ordinary 
 precaution is necessary, and it will be prudent, when 
 distilled water cannot be obtained, to resort to the 
 device mentioned. The next step is to place the plate 
 on the levelling stand, pour a little water over it, so as 
 to cover the surface, whilst we prepare a small quantity 
 of a saturated solution of gallic acid in' water, which 
 is easily done by keeping in stock two or three ounces 
 of a saturated solution of that substance in alcohol,^ 
 .and adding one drach m of this to an ounce of water; 
 
65 
 
 ** 
 
 
 or a saturated solution may be made in boiling water 
 and suffered to cool. Pour off the water from the 
 plate and replace it with this solution, pouring off once 
 or twice, and leaving it to soak into the film for five 
 minutes; in the meantime drop into the developing-^j^, 
 glass five drops of glacial acetic acid, with the same^j^; 
 quantity of solution of nitrate of silver, twent y grains 
 to the ounce of distilled water; add to this the . . 
 fluid from the glass, or, better, a fresh portion o 
 the same, and when it is evenly distributed ovei/*^ 
 the plate, leave absolutely quiet until the whole 
 of the details of the picture are well out. In this, 
 
 which is alluded to as the i% slow developing pro¬ 
 cess^ we find some special advantages: in the first 
 place, from the comparative weakness of the developer, 
 the action, instead of rushing forward, proceeds with 
 great regularity, and, from the small quantity of nitrate 
 of silver added, the particles of silver are successively 
 deposited on the different lights with an evenness and 
 precision approaching the electrotype process; we 
 have, thus, again the advantage of being able to watch 
 progress and leisurely decide upon the period at which 
 we may venture upon pushing the development, if con* 
 sidered necessary; still further, we may frequently by 
 this process obtain beautifully printing negatives, 
 which would at once be rejected, if the plates had 
 been treated with quicker developers in the first 
 instance, as not being sufficiently exposed; the high 
 lights would appear at once, but no amount of silver 
 or strength of developer would produce an harmonious, 
 negative ; in this slow process, however, the image is 
 
 coaxed out, and even under unfavourable circum* 
 
 E 
 
stances as to position and light, the results are very 
 satisfactory. The impetuous operator will of course 
 reject it at once, but to one whose object is to obtain 
 negatives from which he can print with care, and 
 refer to with confidence, the mere suddenness of the 
 appearance of the image will not compensate for 
 delicacy of detail and resistance to light. It is a 
 great mistake to imagine that more work can be done 
 with a tent and the wet process than by the dry, even 
 with such a slow developer as the above, for any num¬ 
 ber of negatives may be undergoing development at 
 the same time; and, taking the general results of a 
 tour, the dry process operator will store in his grooved 
 boxes a far greater number of finished plates than one 
 following the usual out-of-door methods, and at the 
 same time enjoy his trip in every other respect, having- 
 no anxiety about condition of chemicals and numerous 
 other perplexities that, more frequently than not, 
 harrass the other and send him home in a very dis¬ 
 appointed and dyspeptic state. 
 
 But to proceed. Vfe must now consider our deve¬ 
 loping plate under two conditions. After a reasonable 
 time, say half an hour, we find it well developed, with 
 every detail out, and the gradations of light and shade 
 satisfactorily established. In many cases this stage 
 of our operations may be considered as complete ; but 
 the writer, almost invariably, pours off the gallic acid, 
 washes gently, and then uses a fresh developer of 
 pyrogallic acid with citric acid and a drop or two—the 
 less that will answer the purpose the better—of the 
 ordinary twenty-grain solution of nitrate of silver. 
 This is done, not so much to increase the blackness 
 
67 
 
 of the negative as to modify its tone , which it does 
 materially, rendering it more capable of resisting the 
 actinic rays. Once or twice pouring off is sufficient 
 for the purpose, and, if continued too long, an appear¬ 
 ance takes place which is differently accounted for- 
 The writer alludes to that of small breaches in the 
 film, generally called pin-holes. Some attribute these 
 to dust, others to the presence of chlorides in the film; 
 but, when we consider the circumstances under which 
 these holes occur, and the fact that we can produce 
 them when we like, the reason of their appearance and 
 the means of avoiding them will easily suggest them¬ 
 selves. The film of collodion, after it has undergone 
 the previous treatment, is comparatively rigid, and 
 admits of but little extension. Now, with every in¬ 
 crease of shade during development, we introduce a 
 foreign body into its substance, and a time arrives at 
 which the film, unable to receive more, breaks up, 
 exhibiting minute spaces, just where we should expect, 
 at the points of greatest deposit. One of the chief 
 commendations of the slow process of development is, 
 that this deposit proceeds so gradually and evenly 
 that the film has time to accommodate itself to the 
 new circumstances under which it is placed. By the 
 application, however, of a powerful developer and 
 more silver, the film is rent asunder and the negative 
 injured. Whether this explanation be satisfactory to 
 others or not the writer has found it of great value as 
 a practical guide, especially under the second condi¬ 
 tion of the plate under development to which he has 
 Alluded. 
 
 If the plate has been exposed under untoward cir- 
 
68 
 
 cumstanees, perhaps after the slow developer has been 
 floating upon it for half an hour, but very little action 
 is apparent, and the solution, if poured off, is still per¬ 
 fectly clear; a little change of colour is of no conse¬ 
 quence. Return the solution and leave it on for an 
 hour longer, if necessary, until the details are well out; 
 any attempt to push the development in this state is 
 useless, and if the negative must be lost, far better 
 that it should happen from a loosened film—a very 
 unlikely occurrence with ordinary care—than from 
 unequal development; we say better, because even 
 when a film does become loosened, a negative obtained 
 with cost and labour will generally have some portions 
 left, worth preserving. The detail then having come 
 out, pour off the developing solution and wash very 
 carefully, still on the levelling-stand. Prepare now 
 the pyrogallic acid developer, as above, and in both 
 cases, avoid the use of alcohol, adding te n drops of silver 
 solution to the ounce of developer^; pour this on and 
 off the plate several times, until the negative is dark 
 enough in the skies, and again wash with distilled 
 water. The foreground will now, in all probability, be 
 not sufficiently developed, and may be treated thus:— 
 Prepare a fresh quantity of developer, draw it up into 
 a dropping tube with a large bulb, and direct it so as 
 to flow over the less-developed portions of the plate,., 
 held in a slanting position; the fluid is allowed to run. 
 into the developing glass, and the operation repeated.. 
 A very little experience will render the manipulation 
 easy, and this little artifice will, under some circum¬ 
 stances, be found a most useful resource. 
 
 The writer has found this slow development to meet 
 
69 
 
 liis requirements so successfully that he generally uses 
 it in preference to others, especially in the dry pro¬ 
 cesses which he adopts; quicker methods may,however, 
 be frequently used : thus, when a plate has been fully 
 exposed—and it may here be mentioned that a reason¬ 
 able over-exposure does not seem to injure the three 
 first of these processes, such, for instance, as the 
 difference between forty seconds and one and a-half 
 minutes, in Process III.—We may proceed as follows:— 
 
 Pour distilled water over the plate until the film is 
 
 equally moistened, and, having prepared a solution of 
 
 pyrogallic acid, three grains to the ounce of distilled 
 
 water/pour it over the plate, resting on the levelling 
 
 stand, and allow it to remain four or five minutes; 
 
 then into a developing-glass drop five drops of glacial 
 . // * "> 
 acetic acid, and the same quantity of the twenty-grain 
 
 nitrate of silver solution; pour the solution from the 
 
 plate and mix it well with this and return it; in a few 
 
 seconds the image will come out, but the solution must 
 
 be kept in motion or the development will take place 
 
 in patches, especially in the high lights, which no after 
 
 treatment can remedy. The details being well out, 
 
 pour off the developer: wash gently, and remove the 
 
 iodide of silver with a weak solution of cyanide of 
 
 potassium; again wash, and increase the intensity 
 
 as in the former case. 
 
 Sometimes, when the negative is very weak, 
 this is done, the plate, after washing, may be treated^ 
 with a solution of iodine, two drops of tincture to an 
 ounce of water, and the negative be rendered much 
 more capable of receiving a due amount of intensity 
 without hazarding the film. 
 
 b» 
 
70 
 
 A salt of mercury also may be used; and the safest 
 form that the writer has tried is that entered in his 
 note-book as Robertson’s, from Sutton’s Photographic 
 Notes , Oct. 15th, 1862. 
 
 Bichloride of mercury.. 4 grains. 
 
 Iodide of potassium.11 „ 
 
 Water. 1 ounce. 
 
 Mix one part of the above with three of water. 
 Fuming with ammonia, as well as the solution of car¬ 
 bonate of ammonia, recently recommended by Major 
 Russell, has also been tried; but, however well they 
 may suit plates otherwise prepared, in those above 
 mentioned no increase of rapidity w^as gained in de¬ 
 velopment, the film was weakened, and, in fact, the 
 plates thus treated were spoiled. 
 rfy.0 Formic acid with pyrogallic acid, is a rapid deve- 
 /' loper; it not only loosens the film, but is peculiarly 
 apt to develope in patches, and gives a wavy sky. 
 
 On the whole, the writer is convinced that, if a good 
 negative can be produced by the simpler means pro¬ 
 posed, it is far better not to resort to others which 
 involve complicity of treatment; what is by some 
 imagined to be a loss in this important stage is, in fact, 
 a clear gain of time. 
 
 In all the additional artifices mentioned the film is 
 endangered, and it will be prudent, after the prefatory 
 development, to dry the plate and varnish the edges; 
 indeed, this gives so little trouble, that it should be 
 done in all cases when the manipulator only practises the 
 art occasionally, before storing away the dry plate in 
 the box. It is only necessary, whilst the plate is quite 
 hot, to run a small camel’s hair brush, dipped in varnish, 
 
71 
 
 along the edge of the plate for one-eiglith of an inch, 
 holding the edge to be varnished slanting downwards, 
 or it is apt to run into the film by capillary attraction. 
 A very useful application of varnish deserves mention. 
 After varnishing the edges, draw a thin line of varnish^ 
 between the two pictures of an exposed stereoscopic* 
 plate after the first stage of development, taking care, 
 of course, that the plate is thoroughly dry and warm; 
 it sometimes happens that both pictures differ slightly 
 in intensity, and thus, as the developing fluid confines 
 itself within the varnish, we can develope one side 
 more than the other, or, even, with a different deve¬ 
 loper. In the course of the very numerous experiments 
 made with reference to the subject of this pamphlet, 
 the writer has frequently had recourse to this device, 
 w r ith great economy of material and time. 
 
 The iodide of silver is removed from the plate by 
 any of the usual means; but a weak solution of the 
 cyanide of potassium is generally to be preferred/' 7 It 
 is, of course, presumed that the development is com¬ 
 plete, otherwise the details wall be destroyed. In 
 printing by development on dry glass plates, by super¬ 
 position, the image may be brought out almost instan¬ 
 taneously by the usual pyrogallic acid developer, but 
 often, on applying the cyanide solution, it entirely 
 disappears, but is reproduced on applying a fresh 
 quantity of developer; but no amount of silver will 
 bring it up to the point of intensity required for a good 
 negative. The same happens in the process of slow 
 development if an attempt be made to push it before 
 the deposit of silver w-ithin the film is in a condition 
 prepared for this result/ 7 
 
72 
 
 The theory of this interesting subject does not come 
 within the scope of this pamphlet, and it only now 
 remains to give a summary of the respective capabili¬ 
 ties of these methods, according to the writer’s ex¬ 
 perience. 
 
 Process I. is an extremely certain process, and, if 
 the directions given be followed out, can hardly dis¬ 
 appoint the tourist. Any number of plates may be 
 prepared at one time. They will keep for weeks, and 
 need not be developed for some days after exposure ; 
 they require, however, almost as long an exposure 
 as Fothergill plates. The preparation of the malt in¬ 
 fusion demands care, and the operations are rather 
 troublesome, which is no more than may be said of the 
 other dry processes already in use ; but the tourist will 
 have no reason to complain if he arrive at the results 
 which this method is capable of producing. 
 
 Process II.—This requires much less exposure than 
 the preceding, especially if the slow development be 
 employed. The plates seem to keep equally well with 
 the last, but should be developed within a day or two 
 of exposure. 
 
 Process III.—The tourist will most likely select 
 this, as the preservative fluid is very readily prepared, 
 and the plates may be coated during a journey: it is, 
 also, far more sensitive than the last. The principal 
 drawback to its use is, that the plates vary in sensi¬ 
 tiveness with different kinds of glycerine. This can 
 hardly be wondered at, as, in the manufacture of this 
 fluid, which is now largely consumed, various accidents 
 may occur, such as the presence of a minute portion of 
 sulphuric acid, &c., which would unfit it for photo- 
 
73 
 
 graphic purposes. The case has, however, thus been 
 met by the writer:—Having, on trial, found a speci¬ 
 men which gave superior results, he obtained a suffi¬ 
 cient quantity for his requirements : as glycerine costs 
 a mere trifle, this is the safest plan. It would be well 
 if the photographer could make all his own prepara¬ 
 tions, but this is clearly impossible. The matter is 
 under investigation, and, when he has leisure, the 
 writer hopes to fall upon a plan which will secure 
 uniform results. 
 
 Process IV. has only recently been tried, but pro¬ 
 mises to be a valuable addition to the photographer’s 
 resources. 
 
 In the text it should have been mentioned that if the negative after 
 fixing be not dark enough, it may be intensified by any of the usual 
 methods; of course, after fixing, it may be exposed to light for more 
 thorough examination. Allusion has also been made in the text to 
 different kinds of glycerine, as varying in their photographic properties; 
 the same may be remarked of tannin, and the writer would recommend 
 the use of tincture of galls, formed by digesting coarsely-powdered nut- 
 galls in a mixture of equal volumes of absolute alcohol and water for 
 three or four days. Half an ounce, by measure, of this tincture, with 
 half an ounce of distilled water, one drachm of glycerine, and eight drops 
 of glacial acetic acid, thoroughly mixed, form an excellent preservative 
 fluid, and very convenient for the tourist whose stock of plates may be 
 exhausted in a journey. It does not come within the object of this 
 pamphlet to describe specific apparatus; one exception, however, may be 
 admitted. Although it is desirable to prepare the plates at leisure, as 
 recommended, occasions may arise in which they must be prepared at a 
 short notice, and the drying may cause some embarrassment; the follow¬ 
 ing little device meets the case:—Provide three pieces of perforated zinc M 
 plate, half an inch larger than the prepared plate; place one over the /x 
 other in such a way that the holes do not coincide, and tack the corners " 
 together with solder; when the plate is well drained and surface dry,' 1 ' 
 wipe the back carefully; place it on the above—sensitive surface, of 
 course, upwards—and apply a spirit lamp beneath, moving about; the v 
 flame is divided, and the hot air well diffused, without danger of cracking ' 
 the plate, with ordinary care. 
 
SUPPLEMENTARY NOTICE 
 
 OF 
 
 PLANS USEFUL TO THE SCIENTIFIC TRAVELLER 
 AND MISSIONARY. 
 
 Those who have interested themselves with the pro¬ 
 gress of photography, as recorded in the journals, 
 must have observed one feature of advance at least in 
 the far wider scope which has recently become recog¬ 
 nised in the purposes to which it is capable of being 
 applied, and a marked yielding of prejudice towards 
 certain plans which, in the infancy of the art, were the 
 ordinary means employed, but which, in proportion as 
 photography limited itself to a narrower and more 
 specific range of objects, yielded to methods more 
 adapted to its requirements. 
 
 The all-engrossing subject of portrait taking seemed, 
 at one time, to divert research from a more enlarged 
 field and contract it to seeking out modes by which 
 facilities, in the way of rapidity and economy, for this 
 special object could be promoted, and its profits conse¬ 
 quently increased. Those, however, who were capable 
 of estimating the true nature of lieliograpliic science 
 perceived the boundless extent to which it might be 
 applied, and were not slow in calling it into the service 
 of almost every research which required the assistance 
 of art to record its results, in the way of representa¬ 
 tive illustration. In most of these cases, however, it 
 
75 
 
 is possible to avail ourselves of the acknowledged 
 advantage of fixed apparatus, and, indeed, for many 
 of the purposes alluded to, the utmost precision is 
 demanded to attain the objects in view. In such cases 
 also, the amount of detail required can only be met by 
 the collodion process, which assumes a certain amount 
 of material to be always at hand, and of such a nature 
 that very slight causes affect its action. 
 
 There is, however, another class of cases in which, 
 by having recourse to photography, we supply a want 
 keenly felt by those whose duties or inclinations have 
 placed them in positions wdiere, from want of such 
 assistance, most important facts have been left either 
 altogether unrecorded or described without illustration 
 in such a manner as to the reader can convey no ade¬ 
 quate idea of the reality. It is true that the scientific 
 •traveller is almost of necessity capable of sketching 
 from nature, or, at least, of making use of the camera 
 lucida —a very valuable instrument, affording, with 
 sufficient pains, any amount of detail—but both come 
 far behind the requirements of those who are hurried 
 for time, and are totally unfitted for taking such accu¬ 
 rate delineations of evanescent objects as may be pro¬ 
 duced by the least efficient method in photography; 
 and. admitting the great inferiority of such a method 
 to the collodion process, in its present advanced state, 
 in point of beauty and delicacy, it must be remem¬ 
 bered that, in the case alluded to, the object is not so 
 much to produce an attractive picture as faithfully to 
 record a fact, and for this purpose, if he wish to attain 
 his object, the traveller must resort to less perfect 
 methods indeed but such as, with the slightest care 
 
76 
 
 and the least possible inconvenience, will avail him for 
 the purpose contemplated. 
 
 By those who take a narrow view of the matter it 
 may be supposed that the specific duties attached to 
 the office of a missionary also render an acquaintance 
 with photographical operations of indifferent impor¬ 
 tance ; but to every missionary circumstances must 
 constantly arise, the record of which, if not useful to 
 himself as a matter of reference, may, to others at a 
 distance, be replete with interest, and conduce much 
 to forward the objects he has in view. There is one 
 point in which the missionary stands pre-eminently 
 on vantage ground, and which gives his records, 
 whether of description or pictorial, more than ordi¬ 
 nary weight: he is, usually, no mere passing traveller, 
 biassed with present impressions, and liable, though 
 unintentionally, to give undue weight to incidental 
 occurrences; but, dwelling sometimes for lengthened 
 periods amongst the same people and in the same 
 localities, is able to discriminate between what is 
 normal, what only casual; and photography might by 
 him be made largely to contribute to the extension of 
 knowledge with respect to the nature of countries, 
 their produce, and inhabitants. 
 
 It is clear, however, that his availing himself of 
 this art must entirely depend upon its being adapted 
 to the exigencies in which he is placed. The appa¬ 
 ratus, for instance, must be light and compact, the 
 materials few in number, and easily replaced. Now, 
 these are conditions that are not complied with in the 
 ordinary processes; and the object of the writer is to 
 offer a few suggestions which he hopes will be found 
 
77 
 
 to meet the case in point: and, at the outset, it must 
 be kept in mind that -we are supposing a case involving 
 shifts, where it is not possible to employ the appliances 
 for producing anything like a perfect picture, though 
 desirable to retain as exact a facsimile of an object as 
 the circumstances will admit of. Here, then, in the 
 first place, size is no object, as from the smallest deli¬ 
 neations we can increase dimensions to any desirable 
 extent. The scientific traveller or missionary will not 
 then burden himself with any photographic arrange¬ 
 ments larger than those of a stereoscopic size. Again, 
 he will confine himself to such surfaces for retaining 
 an image as involve as little weight as possible; and 
 he must, therefore, almost entirely discard the use of 
 glass, and employ a lighter substance. Fifty plates of 
 mica, for instance, large enough for his purpose, will 
 weigh little more than half-an-ounce, whilst fifty 
 plates of glass of the same size would weigh some 
 pounds; but, as mica even can only be used to a 
 limited extent, he will generally resort to paper, of 
 which a single sheet, 22 by 17, may be made to 
 receive twenty double stereoscopic pictures. Little 
 room now remains for these hints, and the writer will 
 confine himself to two methods useful for the purpose 
 he contemplates, in the one of which mica* is used, in 
 the other paper. 
 
 As the writer has made use of the largest sized 
 mica plates which he could conveniently obtain— 
 those adapted to a quarter size camera—he shall refer 
 to these. It is obvious, however, that they may be 
 cut down to any size. 
 
 * Of course, the -writer is aware that mica is in use for various photo¬ 
 graphic purposes. 
 
78 
 
 Let us suppose the operator to be placed in a posi¬ 
 tion that will allow him to take half-a-dozen quarter 
 glass plates on an expedition, but no more. These may¬ 
 be employed for hundreds of negatives on mica, which 
 can easily be transmitted to a suitable place for copy¬ 
 ing on glass, and thus ensuring more durable negatives. 
 The mica must first be attached to the glass plate with 
 a weak solution of lukewarm gelatine : Major Russell’s 
 formula may be used for this purpose. The gelatine 
 having been poured over the glass plate in the usual 
 manner, and drained for a few seconds, place the mica 
 plate neatly and gently upon it, which can easily be 
 done without inclosing air bubbles, and dry the whole 
 as usual; when dry, examine the surface of the mica 
 by reflected light, and breathe upon it; if spots appear, 
 these can be removed by wiping with a soft wash 
 leather, scrupulously prepared for the purpose, and 
 it must be remembered that mica is easily scratched. 
 "When convinced of its cleanliness, collodion is poured 
 on, in the usual manner, over the -whole surface, both 
 -of mica and glass—the latter being larger than the 
 other, and projecting beyond the edges; sensitise in 
 the bath and proceed precisely as above directed for 
 glass plates, using in preference Process III., and in every 
 other respect to the final varnishing* of the picture as 
 
 * Varnish may not be at hand; the white of egg, diluted with half 
 its bulk of water, maj^ be substituted, drying in the sun or by artificial 
 heat, and carefully avoiding air-bubbles. It appears, on the authority of 
 Dr. Livingstone, that the white of the egg of the crocodile is not coagulable, 
 and the photographic traveller may find it valuable in some of the albu¬ 
 men processes ; at any rate, it is a fluid well deserving examination in a 
 chemical point of view, and the writer would be proud to undertake its 
 analysis. It might be smeared over any glazed surface, evaporated in 
 the sun, and then collected as a gummy mass, when it would be little 
 liable to decomposition. 
 
79 
 
 in the other dry processes. When all is finished, pass 
 the point of a penknife round the outside edge of the 
 mica, and soak the plate for a minute or two in luke¬ 
 warm water, when the mica is to be carefully removed 
 from the glass plate, which may now be washed and 
 prepared for another journey. Many other methods may 
 be used for attaching the mica, such as a drop of col¬ 
 lodion, &c.; but the writer prefers the method proposed. 
 
 It may not, however, be possible to make use of the 
 collodion at all, the stock of materials being exhausted, 
 and we fall back upon paper. Any person who has 
 followed up the calotype process on the plan laid 
 down by Mr. Sutton, in an admirable little work on 
 this subject, published some years ago, will practice 
 the following with ease and success. 
 
 The paper used by the -writer for this purpose is 
 Hollingworth’s negative. Many others have been 
 tried, but those sized with vegetable matter give com¬ 
 paratively weak negatives. Instead of merely coating 
 the surface of the paper with potassio-iodide of silver— 
 which, for this purpose, need not be half the strength 
 of that used for the ordinary Talbotype—it is plunged 
 into the solution and allowed to soak for five minutes, 
 when it is removed and suspended by a clip, with a strip 
 of blotting-paper at the corner, to dry; proceeding in 
 a similar manner with the remaining sheets. A con¬ 
 siderable amount of paper can thus be prepared at the 
 same time. When dry, the excess of iodide of potas¬ 
 sium must be washed out, and the iodide of silver pre¬ 
 cipitated on and within the paper, as usual, omitting 
 none of the precautions necessary in this important 
 stage. When thoroughly washed, the paper is again 
 
80 
 
 dried and stored for use. In preparing for impression, 
 make a solution of—• 
 
 Tannic acid. 5 grains. 
 
 Alcoliol . 2 drachms. 
 
 Water . 6 „ 
 
 Glacial acetic acid.10 drops. 
 
 Solution of nitrate of silver... 5 „ 
 
 Twenty grains to the ounce of distilled water. 
 
 Mix thoroughly, all this portion of the operation being 
 performed where not a particle of white light can 
 enter. The paper is brushed over with this, in the 
 usual manner, excess of fluid removed with blotting 
 paper, and the sensitised paper folded over the glass 
 plate—sensitised surface outwards—and attached to 
 the back by means of gum or other suitable adhesive 
 fluid. The further manipulation is the same as for the 
 Talbotype, but the paper is far more sensitive and gives 
 a much denser negative. One minute and a-half to two 
 minutes, with a stereoscopic lens and small aperture, is 
 sufficient. The glass plates on which the paper is 
 stretched may, of course, be re-employed to any extent; 
 and for this purpose varnished pasteboard or ebonite 
 may be substituted for glass with advantage. 
 
 This paper will be found a most useful travelling 
 companion in another way. It may be convenient to 
 take an average number of dry glass plates on a tour, 
 but not at all sufficient for the objects contemplated. 
 Then print on this paper, by development, and from 
 this positive, at any future time, other negatives may 
 be produced on glass or paper; the original glass can 
 then be washed and prepared for fresh views, keeping, 
 however, a few of the prepared plates for the choicest 
 
81 
 
 objects. With care on the part of the operator, a 
 great number of useful negatives may thus be obtained 
 in very inaccessible places, nor need he be discouraged 
 at the inferiority of his results, under the emergencies 
 we suppose, with the indifferent means he is obliged to 
 employ. The class of objects which he has placed on 
 record are of no ordinary interest or every-day charac¬ 
 ter, and will amply repay the application of various 
 artifices known to the practical intelligent photographer, 
 who, with the most jealous regard to the truthful repro¬ 
 duction of the originals, will be able to correct any 
 accidental blemishes inseparable from the very circum¬ 
 stances under which they were obtained. 
 
 Quite recently another modification of the calotype 
 process has been recommended by Mr. Prichard,* and 
 promises many advantages to the tourist, especially 
 from the circumstance of its reducing the operations to 
 the simplest conditions ; in fact, nothing more is neces¬ 
 sary than preparing the calotype paper in the usual 
 manner with the greatest possible care. This may be 
 done in the light at any convenient time, and in quan¬ 
 tities sufficient to last for months; so that a stock may 
 always be ready. We have now then merely to 
 sensitise for use, with a moderately weak solution of 
 nitrate of silver, in the dark, washing off the solution 
 from the surface, and drying between folds of bibulous 
 paper. Of course, if the sensitised paper is not to be 
 used for some hours, the washing will be attended to 
 with greater care. The writer has only had leisure to 
 make a few experiments on the subject, and had not at 
 hand Turner’s paper, as recommended by Mr. Prichard ; 
 
 *The British Journal of Photography, May 15th, page 203; and 
 June 1st, page 241, of the present year. 
 
 F 
 
82 
 
 but Hollingworth’s paper, saturated with potassio- 
 iodide of silver, as above recommended, answers admi¬ 
 rably—the little black spots excepted—and, although 
 it is not so sensitive as when the solution of tannin is 
 used, it keeps longer and developes with greater clean¬ 
 ness in the lighter parts of the negative. 
 
 Whatever paper plan be used, it is important to 
 wash very thoroughly when the development is com¬ 
 pleted ; and this operation is best effected by pressing 
 the negative between folds of bibulous paper after each 
 washing. 
 
 Those who have practised the paper processes must 
 have been frequently annoyed by the negative losing 
 much of its density in the hyposulphite bath. The 
 writer has tried the sulphocyanide of ammonium, 
 which certainly is safer ; but its present high price is 
 prohibitory to most amateurs: nor is it necessary to 
 remove the iodide of silver at all, as the application of 
 a weak solution of iodide of potassium after the last 
 washing is all that is required. The negative may 
 then be dried and waxed as usual, the slightly prim¬ 
 rose tint of the remaining iodide of silver being far less 
 resistant to light than the brownish colour that is so 
 apt to occur after treatment with hyposulphite of soda. 
 
 It has not been considered necessary to describe the 
 manipulatory steps more minutely ; nor would it be 
 possible to do so in a few words without obscurity. 
 Many special manuals have been devoted to the sub¬ 
 ject, amongst which Mr. Sutton’s handbook, published 
 in 1856, stands pre-eminent; and, by following the 
 directions therein given, the experimentalist cannot 
 fail to obtain the best results of which this paper pro¬ 
 cess is capable. The wax-paper and other methods 
 
83 
 
 have not been mentioned, as the risks and incon¬ 
 veniences attending their use are not less than those 
 of the collodion process, and, therefore, little suited to 
 the tourist in extreme cases. We must, however, 
 allude to the addition of bromine and its compounds, 
 in connexion with the iodides, as a means of producing 
 the sensitive surface ; and on this subject the writer 
 can speak with some confidence, having made it a 
 special matter of inquiry. He believes, then, that 
 the iodide of silver alone is best adapted to the pur¬ 
 pose contemplated in this Appendix. In the first 
 place, it is simpler—a most important consideration, 
 to which many a trifling advantage must be sacrificed; 
 in the next place, the time of exposure with iodide of 
 silver alone is not a matter of much nicety, whereas, 
 with the addition of bromide of silver, if the paper be 
 over-exposed to any great extent the lighter shades 
 and whites of the negative will almost certainly be 
 destroyed during the development. By following 
 Mr. Sutton’s very lucid instructions on this stage of 
 the operations, the paper, merely iodised, may be ex¬ 
 posed several times as long as necessary for impressing 
 an image ; indeed, when the traveller has but one 
 chance of securing an object, over-exposure should 
 always be risked. When the writer practised the 
 wax-paper process, success was just in proportion to 
 the simplicity of the iodising mixture ; and the addi¬ 
 tion of excess of bromides, fluorides, cyanides, chlo¬ 
 rides, and especially sugar of milk, as recommended, 
 led to inferior results or loss of negative. 
 
 The washing-out of the excess of iodide of potas¬ 
 sium, which must be done very thoroughly, has 
 frequently been considered a great objection to this 
 
84 
 
 method ; but this may be accomplished in a much 
 shorter time, and with considerably less water, if the 
 following course be pursued:—The paper, having 
 been saturated with the potassio-iodide of silver, and 
 thoroughly dried, is to be plunged in a dish of distilled 
 or rain water, frequently turning it, and each time 
 passing a feather over the surfaces to remove minute 
 bubbles ; it may then soak for five minutes, when it is 
 removed and hung up with a clip to drain. Whilst this 
 is going on another sheet is treated in a similar manner, 
 and so on with the whole quantity to be prepared. The 
 water is now changed for a fresh supply, and, begin¬ 
 ning with the first sheet, the whole series is proceeded 
 with as before ; and, after thus washing three times, 
 the papers may be finally dried. With two or three 
 dishes, a large quantity may thus be prepared in an 
 hour. 
 
 As the pores of the paper are thoroughly saturated 
 with the silver solution, it has been mentioned that it 
 is unnecessary to use it so concentrated as when one 
 surface only is iodised. 
 
 From the above remarks, then, it will be seen that 
 the materials required for photographic representations, 
 under the difficult circumstances we have supposed, are 
 few in number, light, and occupy but inconsiderable 
 space. As to the manipulations, any person with far 
 less handiness than those to whom our observations 
 are applicable may become an adept after a few days’ 
 practice ; and, as to apparatus, the objective of the 
 travelling telescope may be used for a lens, and a few 
 pieces of thick pasteboard be easily converted into a 
 dark box. Mamy other hints suggest themselves, but 
 time and space prohibit further details. 
 
/