196 
Mr. Faraday on the condensation of 
Cyanogen. 
Some pure cyanuret of mercury was heated until perfectly 
dry. A portion was then inclosed in a green glass tube, in 
the same manner as in former instances, and being collected 
to one end, was decomposed by heat, whilst the other end 
was cooled. The cyanogen soon appeared as a liquid : it 
was limpid, colourless, and very fluid ; not altering its state 
at the temperature of o°. Its refractive power is rather less, 
perhaps, than that of water. A tube containing it being 
opened in the air, the expansion within did not appear to be 
very great ; and the liquid passed with comparative slowness 
into the state of vapour, producing great cold. The vapour, 
being collected over mercury, proved to be pure cyanogen. 
A tube was sealed up with cyanuret of mercury at one 
end, and a drop of water at the other ; the fluid cyanogen 
was then produced in contact with the water. It did not 
mix, at least in any considerable quantity, with that fluid, 
but floated on it, being lighter, though apparently not so 
much so as ether would be. In the course of some days, 
action had taken place, the water had become black, and 
« 
changes, probably such as are known to take place in an 
aqueous solution of cyanogen, occurred. The pressure of 
the vapour of cyanogen appeared by the guage to be 3.6 
or 3.7 atmospheres at 45° F. Its specific gravity was nearly 
0.9. 
Ammonia. 
In searching after liquid ammonia, it became necessary, 
though difficult, to find some dry source of that substance ; 
and I at last resorted to a compound of it, which I had occa- 
