By MAJOR WATERHOUSE.
The collodion process is still preferred for reproducing black and
white designs, drawings, engravings, etc., where very dense negatives
are desirable. The fixed and washed plate is put in a bath of bromide
of copper (ten per cent. solution); the film whitens immediately, and
when the color is even all over, the plate is taken out and plunged
into a bath of the ordinary ferrous oxalate developer. It takes a dark
olive tint, which is very non-actinic, the shadows meanwhile remaining
very clear.--_Photo. News._
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