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alcohol as a test for croton oil. 
English oil; hence the test is true as regards the former, but is not correct as 
regards the latter , or officinal oil , which is wholly and readily soluble in alcohol , 
and the solution thus formed is permanent at ordinary temperatures .” 
Now I presume that these statements, from their general context, are derived 
from the results published by l)r. Pereira in 1850. But if it is so, how is it 
that they are not concordant with those results? In Dr. Pereira we read ‘‘Ex¬ 
periment 2.—Eight volumes of East India croton oil and eight volumes of 
alcohol (sp. gr. -796) gave 8'75 volumes of oil, or ten of oil gave 10’94, being 
an increase of 0'75 volume, or nearly one-tenth.” But the British Pharma¬ 
copoeia states that ten volumes of English-expressed croton oil and ten volumes 
of alcohol gave about 7 - 5 volumes of oil, or a decrease of 2-| volumes, or 
nearly one-fourth. Is this “ about true as regards East Indian croton oil''? 
Is this “ a mistake ”? Have “ the framers of the Pharmacopoeia given the test 
for East Indian croton oil ”? The mistake , I believe, lies with the critic , as 
must be evident. Such statements should surely have been carefully examined 
into before they were put 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 Pharmacopceia 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 Pharmacopceia. 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 mini 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 1 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 105 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- 
