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XVIII. On the application of liquids formed by the condensation 
of gases as mechanical agents. By Sir Humphry Davy, 
Bart. Pres. R. S. 
Read April 17, 1823. 
One of the principal objects that I had in view, in causing 
experiments to be made on the condensation of different 
gaseous bodies, by generating them under pressure, was the 
hope of obtaining vapours, which, from the facility with 
which their elastic forces might be diminished or increased, 
by small decrements or increments of temperature, would be 
applicable to the same purposes as steam. 
As soon as I had obtained muriatic acid in the liquid state, 
a body which M. Berthollet supposed owed its power of 
being separated from bases by other acids, only to the faci- 
lity with which it assumes the gaseous form, I had no 
doubt, as I mentioned in my last communication, that all the 
other gases which have weaker affinities or greater densities, 
and which are absorbable to any extent by water, might be 
rendered fluid by similar means ; and, that the conjecture 
was founded, has been proved by the experiments made with 
so much industry and ingenuity by Mr. Faraday, and which 
I have had the pleasure of communicating to the Society. 
The elasticity of vapours in contact with the liquids from 
which they are produced, under high pressures by high tem- 
peratures, such as those of alcohol and water, is known to in- 
crease in a much higher ratio than the arithmetical one of the 
