_Cement for Glass Baths._--In reply to numerous inquiries which have
appeared in "N. & Q." relative to a good cement for making glass baths for
photographic purposes, I send a recipe which I copied a year or two ago
from some newspaper, and which seems likely to answer the purpose: I have
not tried it myself, not being a photographer.
Caoutchouc 15 grains, chloroform 2 ounces, mastic 1/2 an ounce. The two
first-named ingredients are to be mixed first, and after the gum is
dissolved, the mastic is to be added, and the whole allowed to macerate for
a week. When great elasticity is desirable, more caoutchouc may be added.
This cement is perfectly transparent, and is to be applied with a brush
cold.