  Before describing in detail the manipulations of the process on Dry Collodion plates, it will be necessary to say a few words on the materials and apparatus to be employed, and also to give an account of the means of preparing the various solutions used in the process. First, THE COLLODION.This being the principal material we have to use, we must exercise great care in the selection of a sample that possesses all the characteristics which fit it for a dry process. We must reject all samples that possess great tenacity and contractile power: the Collodion must not be too thick, and it must flow evenly over the plate, and not set in ridges. The best condition for the Iodized Collodion is that known as powdery, that is, being spread on the plate and partially dry, it cannot be removed as a film, but crumbles up on being pressed by the finger in its passage across the plate; in fact, such a condition as The following formula will be found to answer most admirably:
The cotton is to be shaken up with the mixture of alcohol and Æther, and when dissolved, the bottle containing it must be stood aside, in order that any undissolved particles of cotton may subside. The clear liquid may then be decanted into a clean bottle for use. It will be as well to test the quality of the Collodion thus prepared before coating any number of plates with it, for, although the above proportions are very excellent, some little latitude must be allowed for the different degrees of solubility of the various samples of cotton used from time to time. The film, when spread, on the glass plate and partially dry, should not be capable of being removed in the form of a skin, but should give before the finger and crumble up on its being rubbed across the plate. Should any difficulty, however, occur, it would be better to obtain a sample of the Collodion made by an experienced hand, in order that a fair trial may be given to the process. If the Collodion be too contractile it will give rise to blisters in the film, and will wash off the plate during development. The Iodizing Solution that I have found to give the best results in this process is made in the manner following:—
The iodides are to be dissolved by agitation in the alcohol, and the resulting solution is to be carefully filtered, and preserved in a well stoppered bottle. The Iodized Collodion consists of—
The Collodion should always be iodized at least twelve hours before it is required; this interval allows any insoluble matters either from the iodizing solution or from the Collodion itself to fall to the bottom, and enables the operator to pour off the clear solution into a perfectly clean bottle for use. Next in importance to the Iodized Collodion comes THE PRESERVATIVE SOLUTION.Some care is required in the preparation of this solution, in order that it may be clear and bright when finished, and not contain particles that would be deposited in its passage over the Collodion film when being used. The chief precaution to be observed is not to allow it to boil too rapidly, and not to conduct the operation over too fierce a fire; attention Take one ounce of the best transparent gelatine, and throw it into a pipkin in which has been previously placed one pint of distilled water; set this on a slow fire, or over a lamp, until the gelatine is completely melted; then weigh out half ounce of pure citric acid and dissolve it in two ounces of distilled water; add this to the solution of gelatine, stirring it during the addition with a glass rod. The solution in the pipkin is now to be gently boiled for about half an hour: remove it from the fire, and add sufficient distilled water to make up the bulk of liquid to one pint. When quite cold, the liquid in the pipkin is to be filtered through two thicknesses of pure white blotting paper into a bottle perfectly dry and clean. We now add to every pint of filtered preservative solution, two ounces of alcohol of the specific gravity of ·840. The solution thus prepared is ready for use, and should be of a pale amber colour, without any signs of insoluble particles floating in it; should any appear after it has been prepared for some days, a second filtration will remove them, and render the liquid again bright and clear. It will be found better to prepare this solution only in the quantity indicated above, unless the consumption be large, for, although it will keep good for a month or more, my experience points to the fact, that the THE NITRATE OF SILVER BATH.The bath for rendering the plates sensitive does not differ from that recommended for taking negatives with wet Collodion. The formula for its preparation may not be out of place, however, and may assist those whose knowledge of the matter is not perfect.
Dissolve the nitrate of silver in half the water and then add the iodide of cadmium; thoroughly agitate the mixture for five or ten minutes, then add ½ ounce of alcohol, sp. gr. ·840, and fill up with the remaining half of the distilled water; further agitation, and subsequent filtration through two thicknesses of white bibulous paper, will put us in possession of a negative bath. The nitrate of silver being fused, and consequently, pure and neutral, and as it is essential to obtain clean pictures that the bath should be slightly acid in its reaction, we find it necessary to add 5 or 6 minims or drops of pure glacial acetic acid to a bath of 20 ounces, in order that the above condition may obtain. THE DEVELOPING SOLUTIONIs very simple in its nature, being merely a saturated The exact formula is as follows:—
The gallic acid will not be entirely dissolved, but that left at the bottom of the bottle will ensure the solution being saturated; it is better not to filter the developing solution until it is required for use, as it is preferable to allow it to stand over an excess of gallic acid, than for it to be withdrawn after a slight agitation with the crystals; it is a great error to suppose that we obtain a saturated solution of gallic acid by merely agitating the crystals with water for a few moments. The developing solution prepared as above directed will keep good and in working order for some weeks, but when it becomes of a dark color, it would be safer to reject it and prepare a fresh quantity than to run the risk of a failure from an impure and imperfect developing agent. NITRATE OF SILVER SOLUTION,For adding to the gallic acid during development, is composed of
THE FIXING SOLUTIONConsists of a solution of hyposulphite of soda in water, (filtered,) in the following proportion:—
The Apparatus, &c. required in the Dry Collodion process is of the most simple kind, and consist of the following items Glass plates. In the above List we presume that the operator is in possession of a suitable camera and lens, and the usual adjuncts of camera tripod, &c. &c. These should all be of the best kind, otherwise it will be impossible to obtain good results. deco bar THE MANIPULATION. The process of obtaining a picture on Dry Collodion plates is in itself a most simple and easy matter, but there are one or two precautions that appear necessary to ensure success that cannot be lightly neglected. In the first place, it is absolutely certain, that if we want a clean and bright picture, we must have a plate perfectly free from all extraneous matters, such as soap, grease, &c. Various plans for cleaning the glass plate have been proposed, all more or less successful, but in most of them there is one great fault, namely, that of using a powder, as tripoli, rotten-stone, &c. to rub off the dirt with. Now we find that in The next precaution necessary to be observed is, that all the solutions should be perfectly bright and clear; they should be absolutely free from floating particles of any kind. This is essential, as it is impossible to obtain clean pictures without attention to it; the floating bodies in the solution settle on the plate, and form so many nuclei, around which, in the development of the picture, the silver is deposited in an opaque mass, forming spots and blemishes on the surface of the plate. There is one precaution that cannot be dispensed with, and that is, to be sure that the chemicals employed are of absolute purity; without this, success is very problematical, and vexation and disgust the sure reward of its neglect. The process may for convenience be divided into the following stages:— 1.—Cleaning the plate. CLEANING THE PLATE.Fig. 1. The glass plate is first to be thoroughly washed with an abundance of water, and dried on clean cloths; it is then to be placed in the plate holder ( The plate being clean, we proceed to the next step, COATING THE PLATE.Lay a piece of clean blotting paper on the table, larger than the plate we are about to use; place the Fig. 2. The Collodion is then to be poured on, as shown in the diagram ( RENDERING THE PLATE SENSITIVE.Fig. 3. The plate being placed, coated side outwards, on the dipper, is to be plunged without hesitation into the nitrate of silver bath ( Fig. 4. When the plate has rested for half a minute in the bath, it may be withdrawn, and quickly re-immersed. This washing must be continued at intervals, until the greasy appearance goes off, generally for the space of two minutes, when the plate is to be taken out of the bath and placed with its lower edge on a pad of blotting paper, in a position as shown in the cut ( APPLYING THE PRESERVATIVE SOLUTION.Fig. 5. Taking the plate in the left hand by means of the pneumatic holder, incline it as shown in the diagram ( EXPOSURE IN THE CAMERA.Collodion plates preserved as above directed, will keep perfectly good and sensitive for 12 months at least; and from the appearance of the developed image on a plate that has been kept that time, I see at present no reason why, if preserved from the damp, they would not keep indefinitely. In my experiments, I have never found the least difference in sensitiveness, whether the plate be used within a few hours of the time of its preparation, or has been kept for months; until, however, we have had more experience in the matter, it would be safer not to rely on plates more than 12 months old. The time of exposure in the camera, of course varies in this process, under the same circumstances as it does with the wet Collodion; but I have found as a general If the exposure has been of too short duration, the image will come out under the developing solution with difficulty; and after a continued immersion in it will only present the high lights, the deep shadows not being represented, or, if so, in so faint a manner as to be useless in the picture. An over exposed plate, when treated with the developing solution, will almost immediately give indications of the picture; and in a few minutes, the whole of the picture, deep shadows and all, will come put in unnatural force; on looking through the picture thus produced, we shall observe a great flatness in it, there is a want of contrast between the The sky and high lights will first appear, then the half tones, and lastly, the parts of the picture that were in deep shadow will show themselves; this effect should take place in about five minutes from the time of immersion in the developing bath: a picture that comes out sooner than this, is, as a general rule, over exposed; and one that is much after the five minutes before it makes its appearance, may be considered as under exposed. We trust that the above instances may be of service in indicating the average time required for an exposure of the plate, but we must ask the reader not to take the figures given as actual values, but merely as very close approximations to the truth. We will imagine the plate to have been properly exposed, and proceed to THE DEVELOPMENT OF THE PICTURE.It is not necessary that the picture should be developed immediately after exposure in the camera; any time that is convenient to the operator may intervene between the processes, provided the aggregate The development of the picture may be conducted in two ways, either by immersing the plate in baths or dishes, or by placing it on the levelling stand and treating it with the solutions, in their proper order, as detailed below. Each plan possesses certain advantages, but it is of little consequence which one is followed. Perhaps there is less danger of the film washing off if the plate be treated on the levelling stand, and on the other side with large plates it is more difficult to cover them evenly with the developing solution than it is simply to immerse them in a pan of solution. We say to the reader, try both ways, and make your own selection. The plate upon being removed from the camera is placed face upwards in a porcelain or glass dish of a convenient size (not too large), and sufficient distilled water is to be poured over it to cover the surface thoroughly—this is for the purpose of softening the preservative solution, and must be allowed to remain on the plate for five minutes; the plate is then to be lifted in and out of the water by means of the silver hook. This done, remove the plate to a perfectly clean dish, and pour carefully over it the developing solution, composed of
In a few minutes the picture will begin to make its appearance, and will gradually unfold its details under the influence of the developer, until the whole of them are apparent; on raising the plate, however, when this stage of development is reached, and viewing it by transmitted light, the picture will appear weak and poor; we must now remove the plate from the bath, and add 2 drams more of the nitrate silver solution, and having thoroughly mixed it with the gallic acid already in the dish, we return the partially developed plate, which in the course of a few minutes will have acquired a great amount of intensity,—the exact degree can be regulated by the time of immersion: when the picture appears sufficiently intense, it is to be removed from the developing dish, and a gentle stream of water is poured over it, in order to remove any adhering developing solution, and stop all further reducing action on it. During the whole time of the development, the gallic acid should remain quite clear; it will become slightly discoloured before the end of the development, but it ought not at any time to become muddy, or it will deposit a sort of sandy sediment on the surface of the plate, which cannot be removed by subsequent washing. The usual time occupied in the development of a successful picture is from 20 to 30 minutes, it might be developed much quicker by using pyrogallic acid, but at present I give the preference to the The picture being washed free from the adhering developing solution, is to be placed on the levelling stand, and subjected to the seventh part of the process— FIXING THE DEVELOPED IMAGE.This is accomplished by pouring over the surface of the plate sufficient solution of hyposulphite of soda (p. 15) to thoroughly cover it, this will dissolve out the unaltered iodide of silver, and give us a clear and bright picture, in which the deep shadows should be as transparent as the glass itself, and the high lights as dense as a piece of metal, the intermediate tones assuming their proper positions according to the intensity of the light that was concerned in their formation. When the whole of the yellow iodide of silver is removed, the fixing solution may be thrown off, and the plate must be treated with an abundance of water; too much cannot well be given at this stage, as the hyposulphite adheres with great tenacity to the plate, The picture being thoroughly washed, and either dried spontaneously or by the fire, has only to be covered with a film of varnish. And now comes the last operation, of VARNISHING THE FINISHED NEGATIVE.Benzoin varnish is the best coating that can be given to a Collodion negative. It resists the action of pieces of grit; it does not crack; and, above all, it does not, like amber varnish, split off the picture on the slightest friction. The application of this varnish is a very simple matter. The negative is to be again placed on a pneumatic plate holder, and the varnish is to be poured on to the surface in precisely the same manner as the Collodion was at the commencement of the process, the superfluous quantity being returned to the bottle: in a few moments the varnish will be quite dry and hard, and the plate may be handled with perfect safety. I may mention, as a precaution, in varnishing the plate, that it is better to perform that operation in a still atmosphere; as the solvent of the gum being chloroform and very volatile, if it were conducted in a current of air, there might be some difficulty in obtaining an even coating to the picture. In concluding this description of a process, which is at once simple and certain, I would ask the patient attention of those who may do me the honor of repeating my experiments. I have endeavoured to render the details of the process as intelligible as possible, and if I have succeeded in advancing the art of Photography only one step by so doing, I consider that it is an ample return for hours and days spent in anxious thought and laborious experiment. FINIS. SPECIAL LIST OF REQUISITES FOR THE DRY COLLODION PROCESS, SUPPLIED BY Messrs, BLAND & LONG, Opticians, & Photographic Instrument Makers TO THE QUEEN, 153, FLEET STREET, LONDON. BLAND & LONG'S IODIZED DRY COLLODION. This preparation will keep for an indefinite period, and can be exported to any climate, without risk of deterioration. Half-pints, 10s.; Pints, 18s. BLAND & LONG'S PRESERVATIVE SOLUTION,> READY FOR USE.—1s. per pint. BLAND & LONG'S BENZOIN VARNISH, FOR PROTECTING THE FINISHED NEGATIVE. 1s. per oz. This varnish does not require the plate to be warmed; but dries instantly, leaving a perfectly hard transparent coating on the picture. NITRATE OF SILVER BATH, FOR BLAND & LONG'S DRY COLLODION, Ready for immediate use.—7s. 6d. per pint. PURE CHEMICALS.
FOR THE PRICES OF APPARATUS SEE BLAND & LONG'S Illustrated Catalogue of Photographic Apparatus Sent free by post, on application. SENSITIVE DRY COLLODION PLATES, READY FOR EXPOSURE IN THE CAMERA. (LONG'S PROCESS.) Messrs. Bland & Long are now prepared to supply these plates, carefully secured in sealed cases, with full directions for exposure and development, of all sizes and in any quantity, at the following prices:—
LARGER OR OTHER SIZES TO ORDER. The advantages of a certain and simple Dry Collodion Process are so obvious to those who have practised Photography in the open air, that we feel it is merely necessary to introduce the above list to their notice with as few remarks as possible. We would, however, mention a few particulars connected with the process for the information of those who have not hitherto practised the Dry Collodion process, as detailed by Mr. Long. The plates as prepared for sale, are hermetically sealed in an envelope perfectly impervious to air and moisture, they can therefore be exported to any climate without risk of deterioration. Plates prepared by Mr. Long's process will keep sensitive for almost an indefinite period, and can be developed at any time without regard to the date of exposure; this, it will be seen, is of immense advantage to the tourist, as he can delay the development of the whole of his plates until his return. To those Photographers whose inclinations or want of leisure will not admit of their carrying through the first preparation of the plate, these Dry Sensitive Plates will be found invaluable, enabling their whole energy to be directed to the more careful selection of subject. The plates being dry, there is no danger of dust settling on their surfaces; this point will be appreciated by every Photographer. The development of the pictures can be conducted in any room whence the light can be excluded—as the process is simple and clean—three dishes being the only requisites in point of apparatus. To Officers, Engineers, and Architects, these Dry Plates offer a desideratum of no small value, as they are always ready for use, occupy very little room in travelling, and can be used under circumstances which would preclude the adoption of any process that had to be carried out on the spot. BLAND & LONG, Photographic Instrument Makers to the Queen 153, FLEET STREET, LONDON. THE DRY COLLODION PROCESSES. Messrs. BLAND & LONG have invented the following CHANGING THE DRY COLLODION PLATES while working in the fields. The plan has been in use Price according to size. DESCRIPTION AND DIRECTIONS FOR USE. No matter what process we employ to retain the sensitiveness of our plates, it is most objectionable that the glasses should be made to slide by their gravity from the plate-box to the slide; for if we employ either honey, glycerine, or oxymel as preservative agents, the chances are considerably in favor of an amount of dust settling on the surface, the dust being in a great part formed by the attrition of the roughened edges of the plate against the plate-box. Another inconvenience attending the use of a box when the plate has to slide, is the danger that exists under that arrangement of ripping the film from the edges of the plate by the friction against the groove in the box which holds it. These may appear very trivial matters, but they are nevertheless great drawbacks to successful operations. We may mention that the plan we are about to describe is equally applicable to all Cameras of moderate size. We will, however, take our description from the form of apparatus adapted to a double lens Stereoscopic Camera. The Camera (A) is furnished at its back with two wires (B). On these wires slides the plate-box (C), which has previously been fitted at its sides with two sockets (D). Just inside the back of the Camera box is a spring (E), and on the top of the Camera is a button (F), which secures the dark slide in its place. We now slide the box of prepared plates (C) on to the wires (B), the lid of the box opening from the Camera; we The opaque covering is furnished at its side with two elastic rings. Into these thrust the hands, so that the rings may firmly encompass the wrist. Then open the plate-box, and throw the lid quite back. Next unbutton the door of the dark slide, and raise it until the spring (E) flies underneath it, and retains it in a horizontal position. This we will presume to be done with the right hand; the left hand being engaged as soon as the door is opened, in holding the plate that is already in the back in its place. The right hand being now at liberty, comes to the assistance of the left, and the plate that has undergone exposure is safely transferred to the vacant groove in the plate-box. This accomplished, the next plate is to be placed in the back, and the same operations gone through in the inverse order, the left holding the plate in its place, while the right releases the door from the influence of the spring (E), and re-buttons it, leaving the plate quite safe in the dark slide. When we require to focus for a fresh picture, it is only necessary to remove the dark covering from that part of the Camera where the ground glass is placed. The picture can be seen without removing the plate-box or the whole of the covering. It is obvious that there is no limit to the number of glasses that can be taken to the field of operations. In this way, several boxes holding a dozen each, can be strapped together and placed on the Camera, one by one, as occasion or opportunity may direct. H. Silverlock, Printer, Doctors' Commons. PRACTICAL PHOTOGRAPHY, ON GLASS AND PAPER, A Manual, CONTAINING SIMPLE DIRECTIONS FOR THE PRODUCTION OF PORTRAITS, VIEWS, &c. BY THE AGENCY OF LIGHT, INCLUDING THE Collodion, Albumen, Calotype, Waxed Paper, and Positive Paper Processes. By CHARLES A LONG. Fourth Edition, price 1s.; per Post, 1s. 2d. ILLUSTRATED PHOTOGRAPHIC CATALOGUE, FREE BY POST. SPECTACLES: WHEN TO WEAR AND HOW TO USE THEM. ADDRESSED TO THOSE WHO VALUE THEIR SIGHT. By CHARLES A. LONG, THIRD EDITION. POST FREE, SIXPENCE. ALSO, A DESCRIPTIVE AND GENERAL CATALOGUE OF SCIENTIFIC & EDUCATIONAL INSTRUMENTS AND CHEMICAL PREPARATIONS, Manufactured and Sold by BLAND & LONG, OPTICIANS, PHILOSOPHICAL, PHOTOGRAPHICAL, AND CHEMICAL INSTRUMENT MAKERS, AND OPERATIVE CHEMISTS. Free by Post. PUBLISHED BY BLAND & LONG, Opticians, Philosophical and Photographical Instrument Makers to the Queen, 163, FLEET STREET. Transcriber Note Minor typos corrected. Images moved to prevent splitting paragraphs. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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