PHOTOGRAPHIC CORRESPONDENCE.
Precision in Photographic Processes.—I have for a long period observed, and been much annoyed at the circumstance, that many of your photographic correspondents are very remiss when they favour you with recipes for certain processes, in not stating the specific gravity of the articles used; also, in giving the quantities, in not stating if it is by weight or measure.
To illustrate my meaning more fully, I will refer to Vol. viii., p. 252., where a correspondent, in his albumen process, adds "chloride of barium, 7¼ dr." Now, as this article is prepared and sold both in crystals and in a liquid state, it would be desirable to know which of the two is meant before his disciples run the risk of spoiling their paper and losing their time.
How easy would it be to prefix the letter f where fluid oz., dr., or other quantity is meant.
Trusting that this hint may in future induce your correspondents to be as explicit as possible on all points, believe me to be an
Amateur Photographer.
Tent for Collodion.—As I have frequently benefited from the hints of your correspondents, I in my turn hasten to communicate a very simple plan I have contrived for a portable tent for the collodion process, in the hope it may be found to answer with others as well as it has done with me: it is as follows.
Round the legs of my camera stand (a tripod one) I have made a covering for two of the sides, of a double lining of glazed yellow calico, with a few loops at the foot to stake to the ground; the third side is made of thick dark cloth, much wider and larger than to cover the side, which is fastened at one leg of the stand to the calico. The other side is provided with loops to fasten to corresponding buttons on the other leg, and by bending on my knees I can easily pull the dark cloth over my head and back, fasten the loops to the buttons, and then I can perfectly perform any manipulation required, without the risk of any ray of white light entering; and certainly nothing can be more portable.
The simplicity of the thing makes any farther description of it unnecessary, to say nothing of your valuable space.
Jan.
Mr. Sisson's Developing Solution.—The Rev. Mr. Sisson, in a letter I received from him a few days ago, stated that he had been trying, at the recommendation of a gentleman who had written to him upon the subject, a stronger developing solution than that the formula for which he published some time back in your pages, and that it gave splendid positive pictures with very short exposure in the camera.
Since I received his letter I have been able to corroborate his testimony in favour of the stronger solution, and have much pleasure in sending you the formula for the benefit of your readers. It is this: 1½ drachms of protosulphate of iron in five ounces of water, 1 drachm of nitrate of lead, letting it settle for some hours; pour off the clear liquid, and then add to it 2 drachms of acetic acid.
J. Leachman.
20. Compton Terrace, Islington.
Mr. Stewart's Pantograph.—Will some of your photographic readers, who may know the proper size of Mr. Stewart's pantograph, give a detailed description of it? We should have focal length of lens, size of box, and the length of the sliding, parts of it. Cannot the lens be made fast in the middle of the box, provided the frames can be adjusted for different-sized pictures?
R. Elliott.