Brighton.
PHOTOGRAPHIC CORRESPONDENCE.
Mr. Sisson's developing Fluid.—Since I sent you the new formula for Mr. Sisson's positive developer, which you published in Vol. viii., p. 301., Mr. Sisson has written to me to say that if, instead of the acetic acid, you add two drachms of formic acid, the new agent proposed by Mr. Lyte, you certainly obtain the sweetest-toned positives he has ever seen. The pictures, he says, come out very quickly with it indeed; and with a small lens in a sitting-room he can in about ten seconds obtain the most wonderful detail. Every wrinkle in the face, and ladies' lace ribbons or cap-strings, he says, come out beautifully.
The formula then, as improved by Mr. Sisson, is—
Water 5 oz.
Protosulphate of iron 1½ drs.
Nitrate of lead 1 dr.
Formic acid 2 drs.
Perhaps you will give your readers the benefit of it in your next Number. Having tried it myself, I think they will be delighted with the beautiful white silvery tone, without any metallic reflection, produced in pictures developed with it.