On the use of alcohol as a test for the purity of croton oil / by Robert Warington.

  • Warington, Robert, 1807-1867.
Date:
1865
Catalogue details

Licence: Public Domain Mark

Credit: On the use of alcohol as a test for the purity of croton oil / by Robert Warington. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    must be evident. Such statements should surely have been carefully examined into before they were pit in print. But I think I have said enough to remedy the error. ' It is also to be regretted that the experiments conducted on English expressed croton oil of 1850 had not been repeated on genuine samples of oil, expressed from seed in England in 1863, before such strong assertions as to their truth were published. It may be asked, and very properly, how does this subject interest me ? and how come I to take it up ? The case stands thus :—In the month of November, 1863, at the time the sheets of the British Pharmacopoeia were passing through the press, Dr. Frederick Farre, the London editor, requested me to try the test for the purity of croton oil given by the Edinburgh College in 1850, before introducing it into the text of the forthcoming volume. This was done with an oil taken from our own stock, and the result published in January, 1864, in the Pharmacopoeia. This croton oil had been purchased in July, 1863, of Messrs. Horner, who, it is well known, press their own seed in London. The volume of oil which separated may have been stated a trifle lower than what it should have been, owing to the graduations) at that part of the tube employed not being perfectly accurate. It will be seen, however, that this error was only of small amount, and does not affect the general statement. On finding the published test, deduced from this experiment, so warmly criticized before the Pharmaceutical Society by one of their own professors, and the truth of my result so strongly questioned, I lost no time in repeating the trial, in order to satisfy my own mind on the subject. This has led me to the conclusion that the use of alcohol as a test for the purity of croton oil was really of no value, and not to be relied on in any way. Between the buyer and seller this becomes a matter of importance, and, as such, I considered it worthy of publication. The sample of oil first tried was also purchased from Messrs. Horner, in May, 1864 ; the experiments having been commenced in June. For the purpose of more easy comparison, the volume of oil taken in each case is estimated at ten measures, and I have noted against Dr. Pereira’s experiments above the results calculated on the same quantity. Experiment 1.—Ten volumes of English-pressed croton oil (Messrs. Horner’s) and ten volumes of alcohol were mixed, and agitated together ; but, on stand- ing, they soon separated. They were again shaken, and gently warmed ; a perfectly clear solution was obtained, which was set aside, and, in the course of a few hours, had separated into two layers,—the under, or oily one, indicat- ing 9-5 volumes; the upper, or alcoholic one, measuring 10-5 volumes. The alcohol had become of an ordinary sherry tint, from the solution of some part of the oil. About this time a parcel of foreign croton oil was notified on the drug lists for sale, of which Mr. Quincey very kindly forwarded me a sample, ac- companied also by one of croton oil expressed from seed in this country about fourteen years since. The sample of imported oil was marked “ ex Earl of Auckland v. Rotterdam in transit from Batavia.” Experiment 2.—Ten volumes of imported oil were mixed, as before, with ten volumes of alcohol, and briskly agitated. It soon separated, and was then again shaken and gently warmed ; perfect solution followed, and the tube was set aside. In a few hours the contents had separated into two layers, the oil measuring 11*5 volumes, and the alcohol 8‘5 ; also coloured, from solution of part of the oil. This result shows a slight increase on that obtained by Dr. Pereira from East Indian croton oil, which was, from experiment Ho. 2, 10-94 volumes of oil, after separation. Experiment 3.—Ten volumes of the old English-expressed oil were mixed with ten volumes of alcohol, as before, only as they seemed to unite immediately no agitation was required; the mixture was very turbid, but exhibited no signs