220 ALCOHOL-TEST FOR THE PURITY OF CASTOR OIL. 
of oil examined, but I am now convinced this; is not the 
case; and that they depend on other circumstances. To 
Mr. Herring I am indebted for the means of establishing 
this fact, as he has supplied me with authenticated speci- 
mens of East India castor and croton oils, and of castor and 
croton oils expressed in his laboratory. 
Expt. 3— Ten vols, of West India* castor oil were mixed 
with ten vols, of rectified spirit. By shaking, the mixture 
became clear and transparent. After a few minutes it was 
hazy, then cloudy and turbid. The tube was immersed in 
warm water; and the cloudiness disappeared. In eigh- 
teen hours the mixture had separated into two clear liquids ; 
an upper spirituous one of three vols, and a lower oily one 
of seventeen vols. 
Expt. 4. — Ten vols, of East India castor oil were mixed 
with ten vols, of rectified spirit. A cloudy or milky mix- 
ture was obtained, which no shaking would render clear; 
but by immersing the tube in hot water, the mixture became 
quite clear. 
Expt. 5. — Ten vols, of English expressed castor oil were 
mixed with ten vols, of alcohol ; by shaking, a clear trans- 
parent mixture was obtained. After a few minutes a hazi- 
ness began to appear, and in eighteen hours the mixture 
had separated into two strata, an upper spirituous one of 
two vols., and an inferior oily one of eighteen vols. 
Of the three samples of castor oil examined the English 
expressed oil was more soluble in alcohol than either of the 
others. 
Expt. 6 —One vol. of dark colored- English expressed 
croton oil was mixed with one volume of alcohol sp. gr. 
0.796 by shaking without any additional heat, an uniform 
* I am indebted to Mr. Spencer, of Lamb's Conduit Street, for a, 
bottle of this oil. He received it some years ago from the wife of the 
Governor of Tobago, on whose estate it was procured. Its color is 
re ld.sh. 
