ALCOHOL-TEST FOR THE PURITY OF CASTOR OIL. 219 
After several weeks, the mixture had separated into two 
strata ; an upper spirituous one of twelve vols, and an infe- 
rior oily one of one hundred and eighteen vols. The super- 
natent spirit was found to contain oil in solution. 
In this experiment, then, fifty-three vols, of rectified 
spirit must have been held in solution by the castor oil. 
Expf. 2. — Eight vols, of pale or amber colored East India 
croton oil were mixed with eight vols, of alcohol, sp. gr. 
0.796, and gently heated. In two days a separation had 
taken place ; the oil now measured eight volumes and three- 
quarters, while the alcohol measured only seven volumes 
and a quarter. 
In this case the croton oil had taken up three-quarters of 
a volume of alcohol. 
The mutual action of these oils and alcohol appears to 
me to be similar to that of ether and water. If equal 
volumes of pure anhydrous sulphuric ether and water be 
mixed, the mixture on standing separates into two strata ; 
an upper one, consisting of ether holding water in solution, 
and an inferior one, consisting of water, retaining some 
ether in solution. The separation of the two liquids by 
repose, is effected, partly by the difference of specific gra- 
vity, and partly by t te force of cohesion acting between 
homogeneous particles. 
In the case of spirit, and either castor or croton oil, the 
phenomena attending the separation are of a very peculiar 
kind, and require further investigation. By mere shaking 
without any alteration of temperature, a perfectly clear, 
transparent, homogeneous liquid is obtained, which by re- 
pose becomes (often in a few seconds) cloudy, and in a few 
hours or days, a separation into two st,a a of liquids is 
effected. 
II The mutual action of alcohol or rectified spirit, and 
either castor or v croton oil, is not uniform, but varies with 
different samples of oil. At first I was inclined to ascribe 
this variation to differences of purity in the several samples 
