PHOTOGRAPHIC CORRESPONDENCE.
[At the suggestion of several correspondents we have reprinted from The Athenæum of the 22nd Nov. 1851, the article detailing the new process by Mr. Muller referred to by the Rev. Mr. Sisson in our last Number.]
Mr. Muller's Process.—"The following photographic process has been communicated to us by Mr. C. J. Muller, from Patna in the East Indies. We have submitted it to an experienced photographer; and he informs us that it offers many advantages over the Talbotype or the Catalissotype of Dr. Woods, which it somewhat resembles; that it is easy in all its manipulatory details, and certain in its results. We give Mr. Muller's own words—
"'A solution of hydriodate of iron is made in the proportion of eight or ten grains of iodide of iron to one ounce of water. This solution I prepare in the ordinary way with iodine, iron-turnings, and water.—The ordinary paper employed in photography is dressed on one side with a solution of nitrate of lead (fifteen grains of the salt to an ounce of water). When dry, this paper is iodized either by immersing it completely in the solution of the hydriodate of iron, or by floating the leaded surface on the solution. It is removed after the lapse of a minute or two, and lightly dried with blotting-paper. This paper now contains iodide of lead and protonitrate of iron. While still moist, it is rendered sensitive by a solution of nitrate of silver (one hundred grains to the ounce) and placed in the camera. After an exposure of the duration generally required for Talbot's paper, it may be removed to a dark room. If the image is not already out, it will be found speedily to appear in great strength and with beautiful sharpness without any farther application. The yellow tinge of the lights may be removed by a little hyposulphite of soda, though simple washing in water seems to be sufficient to fix the picture. The nitrate of lead nay be omitted; and plain paper only, treated with the solution of the hydriodate of iron, and acetic acid may be used with the nitrate of silver, which renders it more sensitive. The lead, however, imparts a peculiar colorific effect. The red tinge brought about by the lead may be changed to a black one by the use of a dilute solution of sulphate of iron:—by which, indeed, the latent image may be very quickly developed. The papers however will not keep after being iodized.'
"Mr. Muller suggests, that as iodide of lead is completely soluble in nitrate of silver, it might furnish a valuable photographic fluid, which could be applied at any moment when required.
"No small degree of interest attaches to this process, originating in experiments carried on in Central India. It appears perfectly applicable to the albumenized glass and collodion processes."
Detail on Negative Paper.—I have not observed before this, that any photographic operator has "noted" the burnishing of the iodised paper previous to adding the exciting solution, though I know it is usual to burnish before taking a proof. This is a very useful adjunct to obtaining minuteness, and it is a plan I have sometimes adopted. I at first thought it would injure or knock off the iodized surface, but no injury whatever arises from the rubbing. I use a small piece of glass rod, polished flat at one end, so that it may present a facet about half an inch square; but I should imagine a better instrument might be manufactured with a proper handle, and some mode of obtaining pressure; not obtaining sufficient is the cause of a little after-disarrangement if the nitrate of silver is laid on with a brush, but if floated the polish remains.
It cannot be doubted but paper is adequate to any detail; and when a paper shall be manufactured of a perfect kind, there is no reason to suppose but paper generally will rival collodion for most purposes.
Nothing prevents it at present but the uneven surface of paper. It is very nearly perfect in the French negative paper; but that has so many other drawbacks to its use that it cannot be safely depended upon. Our manufacturers have still some improvements to make; for if Canson Frères had left out the blackening chemical in the paper, it would have been better than any of ours in my estimation.