How to Make Blueprint Lantern Slides

Lantern slides of a blue tone that is a pleasing variety from the usual black may be made from spoiled or old plates which have not been developed, by fixing, washing well and then dipping five minutes in the following solution:

Solution A.
Green Iron ammonium citrate150 gr.
Water1 oz.

Solution B.
Potassium ferrocyanide50 gr.
Water1 oz.

Prepare the solutions separately and mix equal parts for use, at the time of employment. Dry the plates in the dark, and keep in the dark until used. Printing is done in the sun, and a vigorous negative must be used, says the Moving Picture World. Exposure, 20 to 30 minutes. Wash 10 minutes in running water and dry. Brown or purple tones may be had by sensitizing with the following solution instead of the above:

Distilled water1 oz.
Sliver nitrate50 gr.
Tartaric or citric acid1/2 oz.

Bathe the plates 5 minutes, keeping the fingers out of the solution, to avoid blackened skin. Dry in the dark. Print to bronzing under a strong negative; fix in hypo, toning first if desired.