LIQUEFACTION, ETC., OF GASEOUS BODIES. 121 
ART. XXXIII.— ON THE LIQUEFACTION AND SOLIDIFICATION 
OF GASEOUS BODIES. A Lecture delivered at the Royal Institu- 
tion; by Professor Faraday. 
Before commencing his lecture, the Professor read an ex- 
tract from a letter written by Professor Liebig, of Giessen, 
shortly after his visit to this country, in which the learned 
writer said, the thing which struck him most in England was 
the persuasion that only those works that had a practical ten- 
dency attracted attention and commanded respect, whilst those 
which were purely scientific were almost unknown; and yet 
the latter were the true sources from which the others flow- 
ed. In Germany, added Liebig, it was the contrary ; but he 
did not say that that was better — in his opinion the golden 
medium was the proper course. Mr. Faraday then proceeded 
with his lecture. The condensation of gases (said he) had 
been brought before the public some years ago. A gas was 
one of those substances in an aerial form which remained per- 
manent under the ordinary circumstances of temperature and 
pressure, whilst vapor was like gas, but which under ordinary 
circumstances was condensable again into liquid. It was at 
one time thought that all gases were perfectly elastic fluids, 
but by his researches he had succeeded in turning into vapor 
the following nine gases, namely, chlorine, muriatic acid, sul- 
phurous acid, sulphuretted hydrogen, carbonic acid, euchlorine, 
nitrous oxide, cyanogen, and ammonia. One of these, name- 
ly, carbonic acid, the late celebrated Thillorier, of Paris, had, 
after many experiments, obtained in a solid state, and Bunsen 
had subsequently obtained also cyanogen in a similar condition. 
But although continued attempts had been made to solidify 
the other seven, and by immersion in deep water a pressure of 
200 atmospheres, i. e., of 3,0001bs. to a square inch, had been 
produced, still they had been unattended with success. He 
would explain what he believed to be the reason of the failure. 
If he took a bottle half filled with ether (and this was La- 
11* 
