ON THE MODE OF ASCERTAINING THE PURITY OF ESSENTIAL OIL OF BITTER ALMONDS.
Mr. Redwood laid before the meeting some samples of oil of bitter almonds, prepared by different makers, together with the results of experiments he had made with the view of ascertaining whether or not they had been subjected to adulteration.
He stated, that his attention had been directed to the subject by more than one of the dealers in this article, in consequence of its having been represented that some of the samples had {206} been adulterated with alcohol, an inference which had been drawn from the fact that the suspected samples had a much lower specific gravity than others met with in commerce.
He had been furnished with five samples from different makers, the specific gravities of which were as follows:—
- 1. 1052.4
- 2. 1055.2
- 3. 1067.
- 4. 1081.
- 5. 1082.2
The merchants having no better mode of testing the quality of this oil than by its flavor, its specific gravity, and other physical characters, it was important to ascertain what reliance could be placed on this class of observations. It was well known that spirit was sometimes mixed with it, the effect of which would be to reduce its specific gravity, and this addition, to the extent to which it would be likely to be made, would not impair the flavor of the oil, or alter its sensible characters in any other way than is above stated. The light oils were, therefore, very naturally suspected to have been reduced with alcohol.
The experiments he had made in reference to this subject had fully satisfied him that the specific gravity of essential oil of bitter almonds, within certain limits, could not be relied on as affording evidence of purity or adulteration. The specimens on the table, to which he had already referred, although differing in specific gravity to the extent of nearly thirty grains in the thousand grain-measures, he believed to be all free from adulteration.
Before describing the tests which he had found to afford the most satisfactory indications, he described the proximate constituents of the crude oil, which vary considerably in proportion in different samples, and hence the differences in density and in some of the properties of the oil.
According to Liebig and Gregory, crude oil of bitter almonds consists of hyduret of benzoyle, hydrocyanic acid, benzoic acid, and benzoine, and these probably are not its only constituents. Of these the two first may be said to be essential constituents, and the others accidental, being the result of changes which {207} the hyduret of benzoyle, or true oil of bitter almonds, undergoes.