NE Se OOS Lr 
Memoir on Sulphuric Ether. 453 
found between the above and ether of abso- 
lute purity. 
Having obtained ether of the sp. gravity 
-72 and alcohol of .83 specific gravity, both 
of which may be considered as very nearly 
pure or free from water; mixtures of these 
two liquids may be made in any proportions 
and the resulting specific gravities ascer-— 
tained; from which we may be enabled to 
estimate the proportions of the two fluids in 
any specimen where no water is present. 
This operation however is more difficult 
than may be imagined. By taking ether and 
diluting it successively with equal portions of 
alcohol, the resulting specific gravities may 
be found in the usual way, provided we 
could guard against any Joss of the mixture. 
But such is the evaporating power of ether, 
especially when pure, that it is impossible to 
pour it from one vessel into another in the 
open air without much loss.—In one instance 
I found that after 6 successive dilutions 
and 12 transfers, made with great care, I 
had lost + of the whole weight used. In 
such case, if the diluting portions are not 
diminished duly, the results must be erro- 
neous. One circumstance is favourable, the 
increase of density by chemical action ap- 
pears to be very small; so that the den- 
