356 
TEST FOR DISTINGUISHING ACETONE. 
"wood naphtha" met with in commerce, when repeatedly 
rectified, over quick lime, will be found to stand these tests; 
and hence, when so rectified, was considered to be the pro- 
per naphtha to be used in medicine. 
A question subsequently seems to have arisen as to the 
dependence to be placed upon these tests, and it was asked, 
Is it pyroacetic or pyroxilic spirit that should be used? — 
and how are we to distinguish readily between the two? 
Accordingly we find this subject fully discussed in the Phar- 
maceutical Journal so far back as the jyear 1843, vol. hi., 
p. 33. 
In this article upon Naphtha, it is stated that pyroacetic 
spirit, or acetone, " is the kind of naphtha which Dr. Hastings 
uses;" and a mode of distinguishing this fluid from pyrox- 
ilic spirit, or ordinary wood naphtha, is pointed out as sug- 
gested by Dr. Ure. It is the way in which nitric acid acts 
upon these two different substances. This test may be de- 
pended upon ; but is almost dangerous, as nitric acid of sp, 
gr. 1.45 acts with explosive violence upon acetone. 
Chloride of calcium affords us a much more ready and 
certain mode of distinguishing acetone from wood-spirit 
naphtha, the former having no action upon it, while the 
latter dissolves and combines with it. It will be found that 
a drop or two of a saturated solution of chloride of cal- 
cium, added to pyroacetic spirit in a test tube, is immiscible 
with it, and separates after agitation, whilst such a solution 
is instantly dissolved by the pyroxilic spirit. 
It should be ascertained beforehand, that the " naphtha" 
under examination does not separate into two fluids, or 
become milky on the addition of water. 
Mr. Bell, in resuming the discussion, said that, although 
it was very important to have a ready means of distin- 
guishing the different liquids which are sold under the 
common name of naphtha — and Mr. Scanlan appeared to 
have supplied this deficiency — yet there was another 
