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BRITISH PHARMACEUTICAL CONFERENCE. 
volatile oils, so far as we can judge from the few exact notions we have of its 
chemical properties. We will not allude in this place to its early history, which 
also ought to be more exactly elucidated. In a chemical point of view, attar of 
roses is a mixture of a liquid oil containing oxygen, to which is due the perfume 
of the attar, and of a solid hydrocarbon (stearoptene) entirely devoid of odour. 
This is the case with a great number of essential oils; their hydrocarbons, how¬ 
ever, are mostly highly aromatic. Besides this, the analyses of Theodore de 
Saussure* and Blanchetf have long since revealed a very striking peculiarity of 
the solid part of the oil, that is, its being composed of carbon and hydrogen in 
equal atomic proportion. X 
The recent experiments of my friend Daniel Hanbury§ have shown that this 
stearoptene is also found in a comparatively large proportion in the roses of 
western and even northern Europe, and that it sometimes exceeds in weight the 
liquid portion. 
The most recent paper on this subject, that of Dr. Baur of Constantinople, in 
the ‘Neues Jahrbuch fiir Pharmacie,’ January, 1867, translated, with valuable 
additions, by Mr. Hanbury,|| also affords some contributions to a knowledge of 
the stearoptene of rose-oil. * 
I have always regarded the properties and the composition of the rose stearop¬ 
tene with some doubts, as they indeed differ from those of all analogous bodies 
hitherto known in essential oils. All the other camphors or stearoptenes of the 
properly so-called essential oils of the vegetable kingdom are composed of carbon, 
hydrogen, and oxygen ; most of them are fusible only at a much more elevated 
temperature, and are possessed of the smell of the oil from which they are 
derived. And as to the hydrocarbons occurring in volatile oils, all are poorer in 
hydrogen, none being composed of an equal number of atoms of the two com¬ 
pounds. 
These facts are certainly encouraging enough to induce one to submit rose- 
oil to a renewed examination, but the great difficulty is to procure an undoubt¬ 
edly pure oil, that of commerce being always adulterated. The sophistication 
in most instances has nothing to do with the stearoptene, and does by no means 
alter it; yet, in order to examine it, I was under the obligation to set aside all 
possible objection referring to the purity of the oil. 
To Mr. Hanbury I am indebted for samples of genuine rose-stearoptene, 
which have enabled me to make the following experiments. The stearoptene in 
question is the same which Mr. Hanbury has already described, and which was 
prepared by himself in London from Mitcham roses. I have nothing important 
to add to his statements concerning the physical properties of the stearoptene, 
which I simply confirm. I tried in vain to obtain perfect crystals of it. If it 
is cautiously melted in the sunlight, the microscopical crystals formed on cool¬ 
ing show a very peculiar shape. Most of them have the form of truncated 
hexahedral pyramids, not, however, belonging to the rhombohedric system, as 
the angles evidently are not equal. Many others are very peculiarly curved, 
nearly S-shaped. Examined under the polarizing microscope, these crys¬ 
tals make a brilliant object from their refractive power. In a pure state the 
melted stearoptene quickly and thoroughly crystallizes on cooling, so com¬ 
pletely that the microscope can easily reveal the presence of most of the solid 
bodies which can possibly be fraudulently added to it. Neither spermaceti nor 
fatty acids resemble it in their crystallographic character, which, indeed, is very 
striking in the pure stearoptene. I scarcely need add that amorphous sub¬ 
stances, like wax, may still more easily be detected by the microscope. But we 
* ‘ Annales de Chimie et de Physique,’ xiii. (1820) 337. 
+ Annalen der Pharm,, vii. (1833) 155. 
§ Pharm. Journ. and Transact, xviii. (1859) 504. 
X C=6, H=l. 
1| Ibid. ix. (1867) 286. 
