250 AMERICAN MIDLAND NATURALIST 
with the formation of ethyl sulphuric acid, according to the 
equation, 
(C,H5)O\ 
(HO) 7 
HOY 
HO) S02 + (C:Hs)OH = 
SO, +HOH 
Barium hydroxide seems to have but slight attraction for large 
quantities of alcohol and may be omitted from consideration. 
Wood alcohol is also thus absorbed by ali the above mentioned 
substances and hence ‘‘Synthol”’ substituted for absolute alcohol 
of late, because cheaper, can be as readily used in the Venetian 
Turpentine method with any of the above-mentioned chemicals. 
One of the best drying agents is zine chloride. Although at first 
this does not seem likely, because the calcium chloride is far more 
porous, practical experiments show that this drawback is quite 
overcome by the greater attraction of the zine chloride for the 
alcohol. When comparing the value of the zine chloride with 
calcium chloride in this respect the absorption is more rapid 
in the case of the former. Other experiments show too, that a 
mixture made by fusing the zinc chloride and the calcium chloride 
together, worked better than the calcium chloride; but evidently 
not because of the increase of porousness, as this fused mixture 
is anything but porous. ; 
Again, it was found that a mechanical mixture of the separately 
fused zinc chloride and calcium chloride also exceeds the calcium 
chloride as a drying agent. Sulphuric acid because of its 
affinity for alcohol appeared to have drying powers equal to the 
above-mentioned substances, but proved impracticable, because 
of its destructive effect upon the stain. 
Results show that zine chloride alone, or in combination 
(with calcium chloride), and sulphuric acid, increase the rapidity 
of absorption by one-half the time required when using calcium 
chloride. The greater the free surface of the drying agent, the more 
closely the vessel is stoppered, and the higher the temperature, 
the greater will be the available vapor tension of the alcohol, 
and therefore the more rapid the absorption. 
The following table shows the time, as exact as could be deter- 
mined, for the concentration of the turpentine, under the conditions 
which follow. In table No. 1, Hempel’s vacuum dessicator was 
used, without applying diminished pressure, of course, and in 
table No. II, large covered crystallizing dishes. Through the whole 
