Henry H. Snelling

The last number (for March, 1849) of the London Art-Journal, gives the following description of a recent improvement in Photographic Manipulation, and as I am desirous of furnishing everything new in the art, I stop the press to add it, entire, to my work.

We shall now proceed to describe the various processes for Photogenic drawing on paper; first, however, impressing on the mind of the experimenter, the necessity which exists for extreme care in every stage of the manipulation. In this portion of my work I am entirely indebted to the works of Professors Hunt, Fisher and others.

The object of this little work is to fill a void much complained of by Daguerreotypists--particularly young beginners.

The author has waited a long time in hopes that some more able pen would be devoted to the subject, but the wants of the numerous, and constantly increasing, class, just mentioned, induces him to wait no longer.

The materials and apparatus necessary for the Calotype process are--

Two or Three Shallow Dishes, for holding distilled water, iodide, potassium, &c.--the same water never being used for two different operations.

White Bibulous Paper.

Photogenic Camera--Fig. 9.

Pressure Frame--Fig 29.

Paper, of the very best quality--directions for the choice of which have been already given.

OXIDE OF SILVER exposed for a few hours to good sunshine, passes into a more decided olive color, than characterises it when first prepared by precipitation from nitrate of silver. Longer exposure renders this color very much lighter, and the covered parts, are found much darker, than those on which the light has acted directly. In some instances where the oxide of silver has been spread on the paper a decided whitening process in some parts, after a few days exposure, is noticed.

At a meeting of the British Association, Professor Grove described a process by which positive calotype pictures could be directly obtained; and thus the necessity to transfer by which the imperfections of the paper are shown, and which is moreover a troublesome and tedious process, is avoided. As light favors most chemical actions, Mr.