M. C. Lea on Picric Acid. 385 
undergone no visible change except the loss of its crystalline 
structure. Heated on platinum foil, the ammonia picrate of nickel 
turns brown and deflagrates with a brilliant white light. 
Picrate of Protoxyd of Chromium.—Chromous acetate dissolved 
in aqueous picric acid yields a brown solution which by sponta- 
neous evaporation dries up to a crust which shows no trace of 
crystallization. 
Picrate of Sesquioxyd of Chromium.—Basic carbonate of chromic 
oxyd boiled with aqueous picrie acid gives a greenish solution 
which by spontaneous evaporation affords greenish crusts with 
no trace of crystallization. But by accurately precipitating the 
violet modification of sulphate of sesquioxyd of chromium with 
picrate of baryta, and leaving the filtrate to evaporate sponta- 
neously, minute greenish needles are obtained. _ 
Picrate of Zine.—Carbonate of zine. readily dissolves in hot 
oa picric acid, and the salt crystallizes out in small prisms 
which effloresce even in well cl vessels. ; : 
Picrate of Cadmium.—Carbonate of cadmium dissolves readily 
in hot aqueous picric acid, and gives by spontaneous evaporation 
very beautiful crystals belonging to the rhombic system, and 
1Isomorphous with the manganese and iron salts, which it very 
closely resembles; it is, however, somewhat lighter in color than 
the manganese salt, and possesses its dichromatic properties in a 
much inferior degree. It is extremely soluble in water, and the 
crystals gradually effloresce even in well closed vessels. By con- 
tinued boiling its aqueous solution deposits a brown powder, . 
probably a basic salt. 
Ammonia Picrate of C 
werfully with a brilliant white light. 
par: : ng Dotonea of Mercur. _—Carbonate of peroxyd of mer- 
cury dissolves by digestion in aqueous picric acid, and ~ b 
evaporation brilliant orange-colored needles, easily soluble in 
Water, and by exposure to air efflorescing to yellow. Heated it 
SECOND SERIES, Vou. XXVI, No. 73.—NOV., 1858. 
50 
