Is it possible by further processes to separate these active principles from the oily matter that contains them?
To solve this question we resorted to the following experiment:—
We took two kilogrammes of croton oil, and for several days we left it in contact with half a kilogramme of alcohol. A distinct separation took place. The upper part, composed of oil and alcohol, did not represent the exact quantity employed; which is explained by the power which the oil has to dissolve 10 per cent. of alcohol. The upper part being decanted, it was necessary to remove the alcohol, to avoid the inconvenience which might have arisen by employing heat for this purpose. Water was added to this liquid, which having become turbid, ether was added. Thus the oil came with the ether to the surface. The ether was removed by free evaporation. During this lengthened process, the effluvia was so pungent as to affect the eyes and nostrils of the operator, and cause blisters to rise on his face. The oil thus obtained is dark-brown, opaque, thick, possessed of a strong smell and acidity. Applied to the skin, it causes almost instantaneous pain, followed by a blister. It is soluble in all proportions in alcohol and ether. Mixed with nine parts of its volume of olive oil, it forms a liquid possessing specific qualities stronger than those of common croton oil.
These facts prove the mobility of the active principles of croton oil, and the possibility of succeeding in obtaining them free from all fatty matter by chemical ingenuity, a task which will be the object of further experiments.
The results from the above experiments are the following:—
1. That the croton oil does not contain a volatile acid.
2. That the sensible acid in croton oil is fixed or retained in the oil, and cannot be separated from it by a heat at 212° Fahr., or even by distillation. {177}
3. That the acrid volatile principle, which exists in this oil, possesses not the qualities of an acid, and has hitherto withstood the chemical operations which were instituted to extract it.
4. That the active principles of croton oil are capable of being separated from one part of the oil, and concentrated in the other.
5. That croton oil is not homogeneous in its composition, but is formed of two parts, one inert, of which alcohol is unable to dissolve more than one-tenth, and a more soluble part, which carries with it all the active principles.