20 
ON THE LIQUEFACTION OF GASES. 
that with the aid of two pumps I was able to subject va- 
rious gases to a pressure of 40 atmospheres, and at the same 
time to submit them to the intense cold obtained under the 
air-pump, and to examine the resulting effects. As I ex- 
pected, the cold produced several results which pressure 
alone would never have done, and principally in the solidi- 
fication of bodies ordinarily gaseous. The following is a 
sketch of the various results : — 
Olefiant gas was condensed to a beautiful colorless trans- 
parent liquid, but it did not solidify ; it dissolves the resinous, 
bituminous and oily bodies. 
Pure hydr iodic acid may be obtained either in the solid 
or liquid state. Solid hydriodic acid is very clear, colorless 
and transparent; generally several fissures traverse the mass; 
it greatly resembles ice. 
Hydrobromic acid may also be obtained either as a lim- 
pid and colorless liquid, or as a clear transparent solid. 
Both these acids require a very careful distillation in 
closed vessels and under great pressure, to be obtained pure 
and colorless. 
Fluosilicic acid was condensed to the liquid state, but it 
is requisite to operate at the lowest temperature. It is ex- 
tremely liquid and mobile, like hot aether ; it then produces 
a pressure of about 9 atmospheres, and gives no sign of so- 
lidification. It is transparent and colorless. 
Fluoboric acid and phosphurelted hydrogen presented 
some results of condensation. 
Hydrochloric acid liquifies readily at less than I atmo- 
sphere of pressure, but it does not solidify. 
Sulphurous acid freezes immediately, as was to be ex- 
pected. 
Sulphuretted hydrogen becomes solid, and then forms a 
white, transparent, crystalline mass, bearing greater resem- 
blance to solid nitrate of ammonia or to camphor, than to 
ice. 
Carbonic acid, when it passes from the liquid to the solid 
