Mr. Faraday on fluid chlorine . 1 65 
some applications of them that I propose to make, before the 
Society. 
I cannot conclude this note without observing, that the 
o-eneration of elastic substances in close vessels, either with 
or without heat, offers much more powerful means of approxi- 
mating their molecules than those dependent upon the appli- 
cation of cold, whether natural or artificial : for, as gases 
diminish only about in volume for every — degree of 
Fahrenheit’s scale, beginning at ordinary temperatures, a 
very slight condensation only can be produced by the most 
powerful freezing mixtures, not half as much as would result 
from the application of a strong flame to one part of a glass 
tube, the other part being of ordinary temperature : and 
when attempts are made to condense gases into fluids by 
sudden mechanical compression, the heat, instantly generated, 
presents a formidable obstacle to the success of the experi- 
ment; whereas, in the compression resulting from their slow 
generation in close vessels, if the process be conducted with 
common precautions, there is no source of difficulty or dan- 
ger ; and it may be easily assisted by artificial cold in cases 
when gases approach near to that point of compression and 
temperature at which they become vapours. 
