230 Proceedings of Philosophical Societies. (Marcu, 
azote, and hydrogen. The truth of this suspicion has been ascer- 
tained by Gay-Lussac. 
On decomposing, with the precautions which he indicates, the 
prussiate of mercury by muriatic acid, he obtained pure prussic 
acid ; and we have already in one of our preceding reports spoken 
of the singular properties which he ascertained it to possess in that 
state, particularly its great volatility. Burning this vapour by means 
_of oxygen and the electric spark, he obtained determinate quantities 
of water, carbonic acid, and azote. He abstracts the oxygen con- 
sumed in the formation of the first two bodies, and obtains this 
conclusion, that one volume of the vapour of prussic acid results 
from the combination and concentration of one volume of the 
vapour of carbon, half a volume of azote, and half a volume of 
hydrogen; or expressing these volumes in weight, according to the 
density of the vapours, 100 parts of the acid contain, 
Carbon ow soja e)s,¢.9.4)5, e969,» 0,0) 9) ese oa 09 SAND 
ZOLA: ck. cok tote fal DIL! Sosc6 lanes is a tna, wtatal 5ES7 0 
ORE as ie x mo WS 0 io 4 m8 min aie iaus aibt Le 
100°00 
This prussic acid contains more azote and less hydrogen than 
other animal substances, from which it is particularly distinguished 
by the absence of oxygen. 
This is the first known hydracide with a decomposable base. 
Gay-Lussac has likewise succeeded in obtaining this radicle in a 
separate state. The accidental name prussic not being proper, he 
has given it the name of cyanogen (that is, producing blue). Hence- 
forth prussic acid must be called hydro-cyanic acid ; its saline com 
pounds, hydro-cyanates; and the compounds of its radicle, cya- 
murets. 
We wish it were in our power to give an account of the nume- 
rous and delicate experiments by which Gay-Lussac has reduced 
under the ene or the other of these classes the different products of 
the action of prussic acid upon bodies, and the properties which he 
has recognised in them. Let it suffice to say that Prussian blue 
rather appears to him a cyanuret of iron containing water than a 
hydro-cyanate, or to use the old name, a prussiate. 
Cyanogen itself possesses peculiar properties. It is a permanently 
elastic fluid, of the specific gravity 1°8064, having a peculiar and 
strong odour, giving a sharp taste to water, and burning with a 
purple flame. Water absorbs four times its volume of it, and 
alcohol 23 times its volume. Its direct analysis gave the same _ 
results as that of hydrocyanic acid, namely one volume of vapour 
of carbon, and half a volume of azote. 
Gay-Lussac has likewise presented to the Class, memoirs on the 
cold produced by evaporation, and on evaporation in air of different 
degrees of temperature and density, in which he expresses by a 
formula the result of his experiments. He has, likewise, given a 
