452 Memoir on Sulphuric Ether. 
part by repeated distillations ; always taking 
the first produce and setting aside the re- 
mainder for other use ; but this method is te- 
dious and expensive. A more ready method 
is to agitate the rectified ether with about its 
own bulk of pure water; after agitation the 
mixture resolyes into two fluids, a heavier ~ 
and a lighter; the lighter may be decanted, 
and will be found about 2 of the volume of 
ether used; it will have the specific gravity 
.73 nearly, and may be considered as ether 
of the first quality. But it is demonstrable 
that it still contains some alcohol, and has be- 
sides acquired a portion of water from this 
process. 'The watery stratum below contains 
the greatest part of the alcohol, and has also 
taken along with it a portion of ‘ether, as is 
evident from the smell, which is much the 
same as that of ether itself. This heavy 
liquid has the specific gravity of .96 or .97 
usually. If this ether of .73 specific gravity 
be again treated with water it will be reduced 
nearly to .72 specific gravity; but it still 
contains minute portions of both alcohol and 
water, the quantities of which are not easily 
appreciated. Subsequent distillation would 
doubtless improve the quality a little ; but 
for most practical purposes there is reason to 
believe that no material difference would be 
