Scientific American Supplement, No. 401

ttled on the subject and carefully dusted the negative, as well as placed it in situ for reproduction, the next thing required is a suitable collodion, and the following will be found all that can be desired:

TRANSFER COLLODION.

Cotton. 3 drachms. Iodide of cadmium. 65 grains. Ammonium iodide. 25 " Bromide of cadmium. 19 " Ammonium bromide. 11 " Alcohol. 15 ounces. Ether. 15 "

The plate thoroughly cleaned and coated with the collodion is now transferred to a bath, as follows:

Nitrate of silver (common) 25 grains to the ounce.

Made slightly acid with nitric acid.

After sensitizing, the plate is exposed in the usual way and taken to the room where pictures are ordinarily developed, and quantum suff. of the following poured into the developing cup to bring out the image:

DEVELOPING SOLUTION.

A Winchester of water, i.e. 80 ounces. Protosulphate