268 
MISCELLANY. 
in alcohol, and crystallizes from this solution in quadrangular prisms. 
It is a good deal used for the cure of scrofulous tumours, in cases where 
iodine and tonics are indicated. — Ibid. 
Pyrophori of easy formation. — M. Vallet has extracted from the Journal 
fur Praktische Chemie, an account of these combustible compounds. It 
is known that when two and a half parts in weight of pure dry tartaric 
acid, deprived of its water af crystallization, and reduced to powder, are 
rapidly mixed with eight parts of peroxide of lead, in a dry capsule, an 
ignition of the whole mass results in a little time, which is very vivid 
and of long continuance. This fact which was first mentioned by Walker, 
led to the supposition that other organic acids might exhibit the same re- 
action with peroxide of lead. M, Botliger has repeated the experiment 
with oxalic and citric acids, and has found that the action of the first upon 
the peroxide of lead was more prompt, if not stronger than that of tartaric 
acid, and that of citric acid was feebler. Thus by mixing together 
5.25 parts in weight of peroxide of lead with one part of oxalic acid dried 
by heated air, or containing 19 parts of water of crystallization, an in- 
stantaneous ignition of the mass took place, but of less duration than 
with tartaric acid, because the oxalic acid contains less carbon than this 
last. In order to obtain a pyrophorus with citric acid, it is necessary to mix 
promptly at a temperature of from 18° R. one atom of citric acid, previous- 
ly melted and kept some time in fusion, then dried and pulverized, with 
two atoms of peroxide of lead. The ignition of the whole mass is as 
vivid and of as long continuance as with tartaric acid. Minium, litharge, 
and carbonate of lead mixed with this last acid, equally afford pyrophori 
according to this author, but not so good as those obtained with the pure 
oxide. — Journal de Pharmucie. 
