468 Memoir on Sulphuric Ether. 
Force of Ether Vapour. 
My former experiments on the force of 
ether having been made with an article not 
of the highest purity, they ought all to ex- 
hibit a force too low for the temperature. 
Such I find to be the fact ; at least within a 
range of temperature of easy investigation, 
that is, from 30° to140°.—The difference 
however is but small, and may, without 
much error, be corrected by deducting 2 or 
3° from the respective temperatures, as given 
in my table. (New System of Chemistry, 
page 14). The apparatus to be used, con- 
sists of a common barometer tube, one bent 
into a syphon at 4 of the length from the 
sealed end, and a tall smaller one bent six or 
seven inches from the sealed end, and having 
the other leg 40 inches long. The first of 
these instruments is best used for atmospheric 
temperatures, having a drop of ether let up 
into the vacuum. The second, is to have its 
short leg filled with mercury, and an inch of 
the other leg, a drop of ether being at the 
top of the mercury in the short leg. This is 
used from temperature 80° to 110 or 120°. 
The third is to have its short leg filled with 
mercury, and a drop of ether as the other, 
—-= ~ 
