564 On the Force of Steam or Vapour 
that of water. The principle however is not 
true, either with regard to spirit of wine or any 
other liquid. Experiments made upon six diffe- 
rent liquids agree in establishing this as a ge- 
neral law ; namely, that the variation of the force 
of vapour from all liquids is the same for the same 
wariation of temperature, reckoning from vapour 
of any given force: thus, assuming a force equal 
to 30 inches of mercury as the standard, it being 
the force of vapour from any liquid boiling in the 
open air, we find aqueous vapour loses half its 
force by a diminution of 30° of temperature ; so 
does the vapour of any other Jiquid lose half its 
force by diminishing its temperature 30° below 
that in which it boils; and the like for any other 
increment or decrement of heat. This being 
the case, it becomes unnecessary to give distinct 
tables of the force of vapour from different 
liquids, as one and the same table is sufficient for 
all_—But it will be proper to relate the experi. 
ments on which this conclusion rests, | 
Experiments on Sulphuric Ether. 
The ether I used boiled in the open air at 
102°.—I filled a barometer tube with mercury, 
moistened by agitation in ether. After a few 
minutes a portion of ether rose to the top of the 
mercurial column, and the height of the column _ 
became stationary, When the whole had acquired 
