The following poisonous coloring materials are sometimes used in
confectionery, says "The Art of Confectionery," but should be avoided:
Scheele's green, a deadly poison, composed of arsenic and copper;
verdigris (green), or acetate of copper--another deadly poison; red oxide
of lead; brown oxide of lead; massicot, or, yellow oxide of lead; oxide of
copper, etc.; vermilion, or sulphuret of mercury; gamboge, chromic acid,
and Naples yellow. "Litmus, also, should be avoided, as it is frequently
incorporated with arsenic and the per-oxide of mercury."
Ultramarine blue is barely admissible, and blue candies are less liable to
be injurious than green, yellow, or red. Marigolds and saffron are
sometimes used for coloring; but the cost of these, particularly the
latter, compared with the minerals, as French and chrome yellows, is so
high, rendering the temptation to substitute the latter so great, that
purchasers should give themselves the benefit of the fear, and use no
yellow candies of a cheap quality. Green candy is the most dangerous. Buy
none, use none; they are mostly very dangerous confections.