22 
ON THE LIQUEFACTION OF GASES. 
Cyanogen freezes, as was already proved by Bussy. 
Perfectly pure and dry ammonia may be obtained as a 
transparent, crystalline white substance, heavier than liquid 
ammonia, and diffusing very little odour, from the weak 
tension of its vapor at this temperature. 
Jlrseniuretted hydrogen and chlorine do not pass from 
the liquid to the solid state. 
Alcohol becomes thick like cold oil, but does not crystal- 
lize any more than caoutchene, camphene and oil of tur- 
pentine, but these bodies become viscid. 
Binoxide of nitrogen and oxide of carbon did not ex- 
hibit the least sign of liquefaction at the lowest temperature, 
and at a pressure of 30 to 35 atmospheres. 
While making these general observations, I have de- 
termined several numbers relative to the point of fusion of 
these various gases and their tension at different tempera- 
tures. The numbers will be given in the memoir which I 
am preparing on this subject, and in which I hope to have 
something new to say respecting the state which oxygen, 
nitrogen or hydrogen may affect in passing to the liquid 
state. Will this latter body present itself in the metallic 
form, as you think ? Will nitrogen prove to be a metal, or 
retain its place among the non-metallic bodies? This, ex- 
perience will show. — Ibid, from *flnn* de Chim. et de Phys. 
