222 ALCOHOL-TEST FOR THE PURITY OF CASTOR OIL. 
not, therefore, have been appreciably effected by the boiling 
proc ?ss. 
Expt. S. — Some English expressed croton oil was heated 
with water^until the water boiled, and the ebullition was 
continued for several minutes. No visible change was 
effected in the oil, and no scum of any kind separated from 
it. When cold, a portion of the oil was mixed with an 
equal volume of alcohol, and shaken up; no heat being ap- 
plied. The mixture became clear and transparent, and no 
separation had taken place in it at the end of two hours. 
As far, therefore, as these two experiments go, they ne- 
gative the supposition, that exposure to the action of boil- 
ing water lessens the solubility of either castor or croton oil 
in alcohol or rectified spirit. 
With the fact of the unequal solubility of different sam- 
ples of apparently genuine castor oil in rectified spirit, I 
have long been familiar; but I am indebted to Mr. Red- 
wood for the information that a similar difference exists be- 
tween the foreign and English croton oils, 
In the Edinburgh Pharrnacopoeia, a note is appended to 
the oil of croton, stating jthat, when agitated with its own 
volume of pure alcohol, and gently heated, it separates on 
standing, without having undergone any diminution. I 
have never been able to verify this statement. Genuine 
croton oil, expressed by Messrs. Herring of London, forms, 
with an equal volume of alcohol, a perfectly transparent 
mixture, without being "gently heated," and does not 
again separate at ordinary temperatures. Mr. Redwood 
has verified the same fact with various samples of genuine 
croton oil, respectively expressed by himself, by Mr. Mor- 
son, by t lie Messrs. Herring, and by Messrs. May & Co., 
and he finds that no subsequent separation takes place, 
unless the mixture be subjected to artificial cold, as a 
freezing mixture, or to the atmosphere during a very cold 
night; and in that case the oil is found to have slightly 
increased in bulk, and the alcohol to have suffered a corres- 
