PHOTOGRAPHIC NOTES AND QUERIES.
Replies to Photographic Questions.—Sir William Newton is right respecting the active properties of sulphuric acid; it should therefore not be stronger than merely tasting of the acid; but it has appeared to me to possess a superior effect in setting the alkalies free. I believe muriatic acid would have precisely the same effect, or Beaufoy's acetic acid, though it would be rather expensive. Starch would be invaluable both for positives or negatives, if it could be laid on perfectly even; but if pinned up to dry it all runs to one corner, and if laid flat it runs into ridges. Perhaps some artist may be able to favour us with the best mode of treating starch; its non-solubility in cold water makes it an invaluable agent in photography.
The above includes a reply to Mr. J. James' first Query: to his second, the solution may be either brushed or floated, but all solutions require even greater care than doing a water-colour drawing, to lay them perfectly flat. The remaining questions depend for answer simply on the experience of the operator: the formula given was simply for iodizing paper; the bringing out, exposure in the camera, &c., have been so clearly described lately by Dr. Diamond, it would be useless to give further directions at present.
G. H. should dispense with the aceto-nitrate and gallic acid, and bring up with gallic acid and glacial acetic acid only. This makes no dirt whatever, and is quite as effective. The marbling
he alludes to proceeds from the sensitive solution not being sufficiently dry when put into the camera. Even if prepared paper is blotted off, which I think a very bad plan, it should have some time allowed it to dry; also the faintness of the image depends either upon not giving time enough, or the aperture he uses for his lens is much too large; or again, he has not found the true chemical focus,—it varies in single meniscus lenses sometimes as much as three-eighths of an inch nearer the eye than the visual:—all these are causes of indistinct images, and require patience to rectify them.
I beg leave to subscribe entirely to Mr. W. Brown's remarks on the subject of Mr. Archer and collodion. I have one of Mr. Horne's handbills, circulated with the first samples of collodion, headed "Archer's prepared collodion" in 1851, and had some of the earliest in the market. That Mr. Archer should fail in trying his own preparation goes for nothing at all, because, at the best of times, and with the most skilful, failures are often numerous and mortifying, in photography above all other arts; therefore, unless some more correct data are given, the merit rests entirely on Mr. Archer.
Weld Taylor.
Bayswater.
Developing Paper Pictures with Pyrogallic Acid (Vol. vii., p. 117.).—Your correspondent R. J. F. asks if any of your photographic correspondents have developed their paper negatives with pyrogallic acid. I have long been in the habit of doing so by the following process. Of Mr. Archer's developing solution, viz.,
| Pyrogallic acid | 3 grs. |
| Acetic acid | 1 drachm. |
| Distilled water | 1 oz. |
take twenty grs. (minims): add an equal quantity of distilled water, and five drops (minims) of acetic acid. I pour the mixture upon a glass plate, and put the sensitive surface of any picture upon it; moving, it up and down by one corner, to prevent the paper being stained, and to observe the development of the picture; which, when sufficiently come out, I blot and wash immediately, and fix with hyposulphite of soda or bromide of potassium.
Thomas Wyatt.
Manchester.
Photography in the Open Air; Improved Camera.—In your Number 172, p. 163., there is a Note of mine in reference to the use to which thin sheet India rubber might be applied. I there alluded to the difficulties attending a single "portable camera," in which all the coating, developing, &c. of your plates is to be done; and for those gentlemen who have the means of carrying about with them a second box, I have devised a modification of Archer's camera, which I think, will prove very useful. It is one which I am about to make for myself. This second box is one in which, when travelling, I can pack my camera, frames, glasses, and chemicals. Having arranged your camera, you proceed to arrange the second box, or "laboratory." This laboratory has three short legs, which screw, or fasten by any simple contrivance, to it, so that it may stand a sufficient height from the ground to allow the bath, which fits in like the one in Archer's camera, to hang beneath it, and also that when working you may do so with ease. It is lighted by either yellow glass or India rubber. There are sleeves of India rubber for your arms, and the holes in the sides of the box traverse nearly the whole of the sides, for the purpose of moving your hands freely from one end of the box to the other; there is also an opening for the head. The bottom of the box is divided: about two-thirds of it, and the nearest to you, has a gutta percha tray, with the four sides, three inches high, fitting it quite tight; and in one corner a tube a few inches long, also of gutta percha, fixed to it, and passing through the bottom of the box, to allow the refuse washings to run off. In the middle of this tray a developing stand of gutta percha is fixed to the bottom, on which to lay the glass plates. The other one-third of the bottom of the laboratory is fitted thus:—There is a slit across the box, immediately before the wall of the tray, for the nitrate of silver bath to slip in. Immediately beyond the edge of the bath is a small fillet of wood running across the box parallel with the bath, and so placed that if the bottom of the dark frame to contain the glass plate is rested against it, and the top of the frame rested against the end of the laboratory, the frame will slope at about an angle of forty-five degrees. Let there be a button, or similar contrivance, on the underside of the lid of the box, that the lid of the dark frame may be fastened to it when open. Bottles of collodion, developing fluid, hypo-soda, or solution of salt, &c., may be arranged in various convenient ways within reach. The proceeding then is very easy. Place the bath-frame and bottles in their places; rear the glass plate in the frame; shut the laboratory lid; place your hands in the sleeves and your head in the hood; fix the door of dark frame to the top; coat the plate; place it in the bath with collodion side from you (it will then be in convenient position when you draw it out of bath to place at once in the frame); fasten the frame door; open the box lid; remove to camera; after taking picture, return frame to its place in camera; bring the plate to developing stand; develop; pour solution of salt over; remove from box; finish outside with hyposulphite of soda.
I have been thus explicit to render the matter as plain and intelligible as possible without aid of diagrams. But I shall be happy to give any
one any further information, either privately, or through "N. & Q." It seems to me that by this contrivance you simplify the process as much as is almost possible; you keep separate the different processes, and run little or no risk of mixing your chemicals, a misfortune which would spoil several hours' work, as well as entail a considerable loss of materials. The box would be no expensive article; any one possessing a little mechanical skill could construct it for himself, and its use as a packing-case for your apparatus would repay the cost.
I have for some time been using a developing fluid, which appears to have some desirable qualifications for it is simple, inexpensive, and keeps good, as far as I have tried it, for a very long period. I have worked with it when it has been made ten weeks; it slightly changes colour, but it throws down no deposit, and does not ever stain the film; when first made, it is colourless as water. Dr. Diamond has kindly undertaken to test its value, and if he pronounces it worthy of being made known, the readers of "N. & Q." shall shortly have the benefit of it.
J. L. Sisson.
Edingthorpe Rectory, Norfolk.
New Effect in Collodion Pictures.—In the course of some experiments I have been following in reference to a photographic subject, a method by which a new effect in pictures on glass may be obtained has occurred to me. Such productions, when treated as positives, are of course white pictures upon a black ground; and although for beauty of detail they are superior to those belonging to any other process, there is a certain harshness and want of artistic effect: to remedy this, I turned my attention towards obtaining a dark picture upon a light ground, as is the case when glass photographs are printed from; in this I have succeeded, and as the modification affords a pleasing variation, it may be acceptable to the tastes of some of your readers. The principle I proceed upon is to copy, by means of the camera, from a previously-taken picture in a negative state. Suppose, for instance, our subject is an out-door view: I take a collodion picture—which would answer for a positive if backed with black: this, viewed by transmitted light, is of course negative,—an effect which may be produced by placing a piece of white paper behind it from this white-backed plate: I take another collodion picture, which, being reversed in light and shade, is negative by reflected light; but viewed as a transparency is positive, and of course retains that character when backed with white paint, paper, or other substance lighter in colour than the parts formed by the reduced silver. Instead of the first picture being formed by the glass, any of the paper processes may be adopted which will afford negative pictures. Copies of prints may be beautifully produced on this principle by obtaining the first or negative by the ordinary process of printing. As these pictures are to form a contrast with a white ground, they should be as brown in tint as possible; nitric acid, or other whitening agents, being avoided in the developing solutions for both negative and positive. By this process the detail and contrasts can be kept far better than by the operation of printing: for it is exceedingly difficult to obtain a picture which will convey to the prepared surface an amount of light corresponding to the natural lights and shades, and the trouble of making collodion copies is far less than printing. There is certainly the drawback of having the copies upon glass: I think, however, that some white flexible substance may be found, upon which the collodion, albumen, &c., may be spread; but if they be intended for framing, of course they are better on glass. The general effect is that of a sepia drawing. The picture first taken and used as a negative, may be preserved as a positive by removing the white back, and treating it in the usual manner.
Permit me to observe, that much confusion arises from the manner in which the terms positive and negative are often used; a negative glass picture is frequently spoken of as a definite, distinct thing; this is not the case, for all photographic pictures upon glass are both negative and positive, accordingly as they are seen upon a back of lighter or darker shade than the reduced silver—by transmitted or reflected light. A picture intended to be printed from is no more a negative than another, its positive character being merely obscured by longer exposure in the camera. When first removed from the developing solution, glass pictures are negative, because they are seen upon the iodide of silver, which is a light ground. This is a thing of course well known to many of your readers, but beginners are, I know, often puzzled by it.
Wm. Tudor Mabley.
Manchester.
Powdered Alum—How does it act?—Sir W. Newton has again kindly informed me of his motive for using the powdered alum, which in "N. & Q." (Vol. vii., p. 141.) he asserts readily removes the hyposulphite of soda. What is the rationale of the chemical action upon the hyposulphite of soda?
W. Adrian Delferier.
40. Sloane Square.