180 
BRITISH PHARMACEUTICAL CONFERENCE. 
The resistances of the essential oils were determined with one cell; and I 
may remark, that I was considerably surprised at the low resistances of the vo¬ 
latile oils, this being the reverse of what, judging from the composition of them 
generally, I was prepared to expect. 
The adulterants of the volatile oils are principally turpentine and alcohol.* 
Compared with any of the essential oils, turpentine has an immense resistance, 
whilst that of alcohol is enormously lower than any of them, except perhaps 
that of oil of bitter almonds, which is so low that I did not measure it. 
The importance of this general fact is at once apparent, since the addition 
either of alcohol or turpentine in the smallest quantity is readily detected ; and 
the quantity denoted by the variation in the deflection, either when compared 
with a standard of known purity, or by the resistances themselves. 
The oils of lemon and bergamot, when mixed with a small proportion of tur¬ 
pentine, do not, however, show such marked differences as the generality of the 
essential oils. The addition of turpentine reduces the conducting power, or, in 
other words, increases the resistances to a very perceptible extent in all oils 
except lemon and bergamot, but in these two last cases it becomes, nevertheless, 
perceptible in the effects of increased resistance,—in these cases, however, a 
property not solely confined to turpentine aids in its detection, and consequently 
enlarges the scope of the application of this test. Large quantities of turpen¬ 
tine are instantly perceptible in increasing the resistances. 
The addition of turpentine to oil of lavender is more strongly marked by this 
test than in any other case. 
The following tables contain the averages of six tests on each oil, taken at 
different times. For reasons noted further on, the same sample should not be 
used for a second test. The volatile oils were obtained from trustworthy sources, 
and were supplied as perfectly genuine and in mature condition. I am particu¬ 
larly indebted to Messrs. I. and H. Smith for the liberal manner in which they 
have supplied me with information respecting the samples obtained from them. 
I met with great difficulty in obtaining samples of cotton-seed oil, and although 
my samples are unauthenticated for condition or purity, I must acknowledge 
my obligation to Mr. Edward Mann, 7, Pall Mall East, for his kindness in pro¬ 
curing them. 
Table of Resistances of Yolatile Oils. 
Genuineness of Samples Authenticated. 
Name of Oil. 
Observed 
Deflection. 
Ohmad’s 
Resistance. 
Peppermint, Ang. 
224 x 8 94 
800,000f 
?> » . 
274 x 8-94 
652,160 1 
„ German. 
236 x 8-94 
759,000 
Caraway. 
202 x 8-94 
90,000 
„ 2nd sample. 
202 x 8-94 
90,000 
Cloves . 
205 x 8-94 
81,000 
Bitter Almonds. 
. § 
Aniseed. 
57x8-94 
3', 144,000 
Bergamot. 
94 x 8-94 
1,906,000|| 
Lemon. 
53x8-94 
3',376,000 
Lavender, Ang. 
310 
5,244,000** 
„ Mitcham. 
250x8-94 
717,000ft 
* The foreign oils are, no doubt, sometimes entirely substituted for the English oils, or 
largely diluted with them. 
f 1858 product. J 1861 product. § Beyond range of observation. 
i| Sample turbid. ** Deflection rising rapidly to 350. 
ft Deflection increasing slowly. This arises from electrolysis. 
