388 
ALCOHOL AS A TEST FOR CROTON OIL. 
whether true or not, is altogether unimportant, so far as the test of the British 
Pharmacopoeia is concerned, for my criticisms were not intended to supply a 
test for a nou-officinal croton oil, but essentially to indicate that the test for the 
officinal “ English croton oil ” given in the British Pharmacopoeia was incorrect 
according to the investigations of Pereira and Itedwood. I may add also, as 
Mr. Waring ton regrets that I did not repeat the experiments, that the test was 
not in accordance with the results obtained by myself. 
In reference to this test we will now quote Mr. Warington, as follows :—“It 
may be asked, and very properly (he says), 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 in¬ 
troducing 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.” 
Mr. Warington here admits that from a single experiment upon one sample of 
oil only, and when the results obtained by him were entirely opposed to those 
previously published by Pereira and Redwood, the test for English croton oil was 
upon his authority and recommendation inserted in the British Pharmacopoeia. 
With how much more care Dr. Pereira proceeded before he published the 
opposite results to those obtained by Mr. Warington will appear from the fol¬ 
lowing extract from his k Materia Medica : ’—“This fact, which was mentioned 
to me by Mr. Redwood, he has verified with various samples of croton oil ex¬ 
pressed respectively by himself, by Mr. Morson, by Messrs. Herrings, and by 
Messrs. May and Co. 1 have verified it with a sample expressed by Messrs. 
Herrings.” 
Mr. Warington then adds,—“ On finding the published test, deduced from 
this experiment, so warmly criticised 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 sub¬ 
ject.” Mr. Warington then performed a number of carefully conducted ex¬ 
periments, and obtained the valuable results which he has given in his paper ; 
these all tend to show that the solubility of English croton oil is liable to 
fluctuations, according to the length of time the oil has been expressed and the 
temperature at the time the experiments are performed ; and he concludes as 
follows :—“ I cannot but consider that a test which is open to so many weighty 
objections, both from the influence of small fluctuations of temperature, and 
for indicating the purity of a material liable to such marked differences from 
the effects of such natural and in some cases inevitable chemical changes, is per¬ 
fectly useless as a reliable indication of purity.” 
It is much to be regretted that Mr. Warington did not try a similar series of 
experiments before he recommended the introduction of a test into the British 
Pharmacopoeia, which he now admits is perfectly useless as a reliable indication 
of purity, rather than afterwards. “ On finding the published test, so warmly 
criticized before the Pharmaceutical Society by one of their own professors.” I 
will conclude by asking, who has made the mistake with regard to the test? Is 
it the critic who first called attention to its being entirely opposed to the pub¬ 
lished results of Pereira and Redwood? or is it the criticiser of the critic who 
recommended its insertion into the British Pharmacopoeia on the strength of a 
solitary experiment? and who now upon further investigation admits that it is 
perfectly useless as a reliable indication of purity? 
