384 M. C. Lea on Picric Acid. 
Prierate of Peroxyd of Iron.—Picric acid in solution boiled with 
freshly precipitated and still moist peroxyd of iron takes up so 
little of the ae as to give ~ me indications with sulpho- 
+ oR of potass By accurately — picrate of 
ta with pormaliants of iron and leaving to crystallize ty 
spontaneous evaporation, the perpicrate of iron is obtain 
small yellowish red prisms and yellow needles, which, daria 
larly when examined with a lens, exhibit a beautiful amethyst 
reflexion. Heated on platinum foil, it fuses to a red liquid which 
grows deeper and deeper in color until it takes fire and burns 
with a hissing noise 
Picrate of Cobalt.—The neutral salt is marae obtained ra rt 
ing a somewhat concentrated solution of chlorid of cobalt 
similar ante of picrate of soda. If the eihtibes be hot the er 
erystallizes out by cooling. In this way beautiful amber-brown 
tals may be obtained which often extend entirely across the 
evaporating dish, and which must be freed from adhering chlorid 
ium by recrystallization from a small quantity of hot water. 
his process is more easy and less wasteful than that recom- 
etomttety in the text-books, of eating picric acid with carbonate 
of cobalt and separating the neutral from the basic salt by 
lute alcohol. Heated on platinum foil, the picrate of cobalt melts, 
becoming reddish- —o and deflagrates with a white light. 
te of Nic Hydrated oxyd of nickel readily dissolves 
in hot aqueous ios ds sick, giving a yellow solution which yields 
green crystals by evaporation. By spontaneous evaporation 
beautiful prisms are obtained, pete fis an inch and a half or 
more in length. By heat it becomes first yellow, then brown, 
and finally deflagrates with a brilliant white light. 
Ammonia Picrate of Nickel.—This beautiful but very unstable 
salt is formed whenever an ammoniacal solution of chlorid of mic- 
kel is mixed = a tet = I have generally used picrate 
= yellow pres p vitata takes plies: which under the compound 
pres to consist of bundles of transparent acicular 
ergata, ek cold water in sufficient quantity decomposes ’ this 
Placed on a filter and washed the water runs through bright 
yellow, and after a sufficient time the filter is found to contain 
nothing but oe — of nickel, free from any trace of picri¢ 
aitd,:.com a asic carbonate by exposure to the 
y evaporation yields, as might > be 
icrate of ammonia. It is, therefore, evi- 
