470 Scientific Intelligence. {Dxc. 
VII. Cyanogen. " - 
Cyanogen is easily obtained by exposing what was formerly called 
russiate of mercury, but which Gay-Lussac has shown to be a 
‘compound of cyanogen and mercury, to the heat of alamp. The 
salt should be very dry. A gas comes over, which must be re- 
ceived over mercury. It is cyanogen gas. This gas has a very 
strong and peculiar odour. Water dissolves it, and acquires a sharp 
taste. It is inflammable, and burns with a blueish purple flame. 
Its specific gravity is 1°8064. It may be exposed toa very strong 
heat, without decomposition. Water dissolves 41 volumes of it, 
alcohol 23 volumes, and alcohol and oil of turpentine at least’ as 
much as water. It reddens infusion of litmus, and combines’ with 
the salifiable bases, and therefore possesses acid properties. “Phos- 
phorus, sulphur, and iodine, may be volatilized in it without 
change. Hydrogen has no action on it. Copper and gold ‘do ‘not 
combine with it, but iron partly decomposes it at a red heat. Potas- 
‘sium absorbs just as much of it in bulk as it separates of hydrogen 
from water. 
For combustion it requires twice its bulk of oxygen gas. It deto- 
nates with great violence, anj with a bluish flame. 100 measures 
of cyanogen thus burn and form 200 measures of carbonic acid gas, 
and leave 100 measures of azote. Cyanogen combines with several 
of the metals. It unites also with the alkalies and alkaline earths. 
When these compounds are dissolved in water, the cyanogen is de- 
composed, and converted into carbonic acid, ammonia, and hydro- 
cyanie acid; and what is curious, equal volumes of these three 
substances are formed, supposing them all in the gaseous state. 
VIL. Chloro-cyanic Acid. 
Berthollet observed long ago, that when chlorine was mixed 
with hydro-cyanic acid, the properties of this latter acid were altered. 
Its smell became much stronger, and it precipitated iron, not blue 
as before; but green. The new substance thus obtained was called 
oxy-prussic acid, because it was considered to be a compound of 
oxygen and prussic acid. Gay-Lussac has ascertained that it is a 
compound of equal volumes of chlorine and cyanogen, and on 
that account has given it the name of chloro-cyanic acid. 
’ To obtain it, he passed a current of chlorine gas into hydro-eyanic 
acid, till that acid acquired the property of destroying the colour of 
a'solution of indigo in sulphuric acid. By agitating the liquid with 
mercury he got rid of the excess of chlorine. The liquid was 
then distilled. He obtained a gas which was a mixture of chloro- 
cyanic acid and carbonic acid; but chloro-cyanic acid is not an 
elastic fluid, but a liquid. He obtained it in that state by filling 
two thirds of a glass Jar with mercury, and the other third with the 
hydro-cyanic acid, saturated with chlorine. This jar was placed 
inverted over mercury, under the receiver of an air-pump. On 
producing a vacuum the mercury and liquid were driven out of 
