Henry H. Snelling

Under this title a process has been brought forward by Mr. Hunt. It consists of the application of a solution of succinic acid to paper, which is subsequently washed over with nitrate of silver. The image is then to be taken either in the camera or otherwise, as required, and is brought out by the application of the sulphate of iron in solution. Although this process has not come into general use, its exact description may be interesting to the general reader, and we therefore subjoin it.

Many efforts have been made to render chromatic acid an active agent in the production of photographs. M. Ponton used a paper saturated with bichromate of potash, and this was one of the earliest photogenic processes. M. Becquerel improved upon this process by sizing the paper with starch previous to the application of the bichromate of potash solution, which enabled him to convert the negative picture into a positive one, by the use of a solution of iodine, which combined with that portion of the starch on which the light had not acted.

by Henry H. Snelling

The expressed juice, alcoholic, or watery infusion of flowers, or vegetable substances, may be made the media of photogenic action. This fact was first discovered by Sir John Herschel. We have already given a few examples of this in the third chapter.

New York, January 27, 1849. E. ANTHONY, ESQ.

This process is a discovery of Sir John Herschel and receives its name from the fact that both negative and positive photographs can be produced by one process. The positive pictures obtained by it have a perfect resemblance to impressions of engravings with common printer's ink. The process, although not yet fully carried out, promises to be of vast utility.