1819. History of Anthrazothionie Acid. 41 
longer. From the very first, a peculiar penetrating substance 
was disengaged, having a peculiar smell (which is not similar 
to that of prussic acid). When a burning body is brought into 
contact with this substance, it takes fire, and burns with a light 
white flame mixed with blue, which may be extinguished by 
again putting the cover over the crucible.. This gas is either the 
cyanogen discovered by Gay-Lussac, or prussic acid ; for if a 
paper moistened with liquid ammonia be held over it for a while, 
it gives with an acid solution of oxide of iron excellent prussian. 
blue ; but J have not made any more accurate experiments on it. 
The mass in the crucible concretes together, melts, assumes an 
appearance very similar to graphite, and shows here and there, 
particularly along the fracture, a quantity of small metallic specks, 
similar to iron with a silvery lustre. When at this period, the 
fire is raised, by blowing to a white heat there comes over at 
last anothet gas, the bubbles of which as soon as they pass 
through the melted graphite-looking matter take fire in the air 
of their own accord. A white flame and weak explosion cha- 
racterize this combustion. If a polished plate of steel be held 
over the crucible at this period, it becomes covered with subtile 
flocks of a whitish grey colour, which act as an alkali upon tur- 
meric paper. As the gas is always distinguished by the peculiar 
smell already mentioned, and as it always forms prussian blue 
when treated with liquid ammonia and an acid solution of oxide 
of iron, it must consist of cyanogen mixed with potash, or of 
prussic acid gas containing potash.* 
Sect. 3.—The black, graphite looking matter in the crucible 
is now allowed to cool, it is taken out, rubbed down to powder, 
and set to digest in alcohol. After some time, the liquid is passed 
through the filter, and a new portion of alcohol poured upon the 
powder. This digestion of new alcohol is continued till the 
liquid ceases to alter the colour of solutions of iron. The alco- 
holic solution is usually colomless and transparent, though 
sometimes it has a blood red colour, owing to the presence of a 
portion of anthrazothionate of iron, from which it is easy to free 
it by the addition of a few drops of the alcoholic solution of 
* When the experiment is repeated in proper metallic tubes (which better keep 
off the action of atmospherical oxygen), there can be no doubt that potassium will 
be obtained at a lower temperature, and with greater ease, than by the method 
hitherto practised, Ought not this gas to be formed when potassium is heated in 
eyanogen? And ought not the hydrogen gas, which remains behind when the excess 
of cyanogen is absorbed by potash, to be ascribed to the decomposition of the water 
which the potassium in the cyanogen finds in the potash? Gay-Lussac found that 
when 48 or 50 volumes of cyanogen were combined with potassium, the remaining 
cyanogen, after it had been absorbed by potash (which always contains moisture), 
left a residuum amounting to 12 parts. But this isan equivalent to 24 vilumes of 
hydrocyanic acid: hence it follows that the cyanogen under examination must 
have contained the third of its volume of hydrocyanic acid, When we consider 
Gay-Lussac’s accuracy, and the excellent apparatus and reagents which he had at 
his disposal, so great an impurity in the cyanogen prepared by him, and contrary to 
tris wishes, is very unlikely, 
2 
