ON A RECENTLY PROPOSED TEST, ETC. 
501 
not genuine, gave the indications of genuine otto. Under these circumstances, 
he did not think that any reliance could be placed on this test, and as a bad test 
was worse than none at all, it was desirable that pharmaceutists should be 
cautioned against judging of the genuine or spurious character of a costly drug 
such as otto of roses by such imperfect means. He had frequently had occasion 
to investigate means that were suggested for testing essential oils, and had 
generally found them to be imperfect and unsatisfactory. There was often con¬ 
siderable difficulty in judging of the genuineness of an essentia] oil, in conse¬ 
quence of differences occurring in genuine samples of the same oil. These dif¬ 
ferences arose partly from the influence of soil and climate upon the plants 
yielding the oils, partly from the process adopted in their separation from the 
plant, and partly from changes which occurred in keeping them. Thus English 
otto of roses contained a large proportion of a solid fatty matter, which gave it 
a high melting-point, and caused the peculiar reaction, in the application of 
Hager’s test, resembling that caused by spermaceti. Some samples of French 
otto also contained a good deal of this solid fat, while Turkish otto contained 
but little of it. It could hardly be expected that different samples of an oil 
thus differing in composition should give the same reaction with a test. There 
were many other oils in which similar differences were observed. Essential oil 
of almonds differed materially in its characters, properties, and composition, 
according to the process by which it was produced. Oil of cloves, again, differed 
at different stages of the process of distillation. Then most essential oils under¬ 
went changes when they were long kept, especially if exposed to the air. Dif¬ 
ferences thus caused not only affected the chemical reactions of the oils, but also 
their physical characters, so that no great reliance could be placed on specific 
gravity, refractive power, or the power of rotating a ray of polarized light, for 
all these characters were liable to chauge under the influences alluded to. 
Thus, for instance, it was well known that French and English oil of turpentine 
rotated the plane of polarization of a ray of light in opposite directions. 
Mr. D. FI anbury explained the circumstances under which he had obtained 
the samples of otto of roses and of oils used for its adulteration, which he had 
supplied to Dr. Redwood for the experiments which had been described. He 
thought the samples of otto might be relied upon as genuine, for he received 
them directly from the manufacturers as genuine samples. He believed the oils 
labelled Idris Yaghi and Roshe Oil were identical, and their similar reactions 
with Hager’s test tended to confirm this. 
Dr. Attfield remarked that, in confirmation of what had been stated by 
Dr. Redwood, he might mention the fact that some time ago he received two 
samples of oil of cloves from Mr. Whipple, both of which were obtained in the 
same operation, and he found one to be a pure hydrocarbon, while the other 
consisted of eugenic acid—a body containing oxygen. 
Dr. Edwards, of Liverpool, suggested that probably spectrum analysis might 
be applied to aid in detecting intrinsic differences in essential oils. 
Mr. Mee inquired if Dr. Redwood had made any experiments to ascertain 
whether the cohesion figures described by Mr. Tomlinson might be used as 
means of testing the oils alluded to. 
Dr. Redwood replied that he had not done so, and he thought such a method 
of testing, which depended on the physical condition of the oil, could not be of 
much use, as these and other essential oils are subject to constant variation in 
their physical conditions. 
Dr. Waring stated that oil of sandal-wood was used in India to adulterate 
otto of roses. 
