On the Constitution of mixed Gases, Sc. 537 
182°, it is of half that force; and at 40° above, 
or 252°, itis of double the force;, so likewise 
the vapour from sulphuric ether which boils at 
102°, then supporting 30 inches of mercury, at 
30° below that temperature it has half the force, 
and at 40° above it, double the force: and so in 
other liquids. Moreover, the force of aqueous 
vapour of 60° is nearly equal to inch of mer- 
cury, when admitted into a torricellian vacuum ; 
and water of the same temperature, confined 
with perfectly dry air, increases the elasticity 
to just the same amount, 
3. The quantity of any liquid evaporated in 
the open air is directly as the force of steam from 
such liquid at its temperature, all other circum- 
stances being the same. 
4. All-elastic fluids expand the same quan- 
tity by heat: and this expansion is very nearly in 
the same equable way as that of mercury; at 
least from 32° to 212°.—It seems probable the 
expansion of each particle of the same fluid, or its 
- sphere of influence, is directly as the quan- 
tity of heat combined with it; and consequently 
the expansion of the fluid as the cube of the 
temperature, reckoned from the point of sta 
privation. 
Having now stated the chief principles which 
seem to be established from the following series 
