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SELECTED ARTICLES. 
barometer of 760 mm , is 4 6°. 6 C; the temperature of the 
vapor which is disengaged from a boiling mixture of carburet 
of sulphur and water, is 43°.5 C. If we suppose, however, 
that the elasticity of the vapor of carburet of sulphur at that 
temperature is equal to the elasticity of these vapors at a 
temperature 3°.l C. lower, that is to say at 96°. 9 C, we will 
find, by the tables of Biot, that the elasticity of the vapors of 
carburet of sulphur at 43°. 5 C, is equal to 680 mm ; the elas- 
ticity of the vapors of water, at the same temperature, is 
63 mm .5. Then the sum of the elasticity of the vapors of the 
two liquids at that temperature, is 743 mm .5. The barometer, 
during the observation, indicating 752 mm .2, then it will be 
seen that, at the temperature of 43°.5 C, the sum of the 
elasticities of the vapors of water and carburet of sulphur, is 
such as to be nearly equal to the pressure exercised upon 
them; the difference may be attributed to errors of observa- 
tion. We cannot apply this with the same success to oil of 
turpentine and water, because, for so great a difference of 
temperature from the boiling point of the mixture, at 94°.5 C, 
to that of the oil of turpentine at 156°.8, the elasticity of the 
vapor of this oil is not equal to the elasticity of the vapor of 
water for the same difference of temperature, to the boiling 
point of water. 
We might, perhaps, inversely, use the temperature of the 
vapors of a mixture to determine the elasticity of the vapor 
of one of these liquids, that of the other being known. It is 
to be regretted that the number of volatile substances which 
do not mix, is so small that we can by this mode determine 
the elasticity of only a small number of vapors, and that, at 
the most, for a single point of temperature below that of ebul- 
lition. 
If the more volatile liquid occupies the superior portion, it 
receives its heat from the liquid which is below, as if it was 
alone in the vessel. It is striking that there are so few liquids 
which do not act upon each other, of which the more volatile is 
the lighter. In my experiments I have only used mercury with 
water and with the oil of turpentine, and water with the oil of 
