to continue fluid at 2Y. According to the observations of Dr. Clarke, of Cambridge, this oil crystallizes in 
rectangular four-sided prisms with square bases. 
Chevreul, in his Reclierches stir les Corps gras, has shewn that fixed oils consist of two proximate principles, 
upon the relative proportions of which in a great measure depend their relative degrees of fluidity, solidity, 
&c., and therefore that, as afforded by nature, they are doubly compound bodies. By exposure to a low 
temperature these principles separate, the one solidifying much sooner than the other, which remains fluid 
at very low temperatures indeed. The first, Chevreul has named Stearine, from nsaq, suet, in which it is 
the chief ingredient. It likewise abounds in the butter nut oil, and in the palm oil, which are solid at all 
ordinary temperatures. The second he has called Elaine (from i'Aaov oil.) This principle may be obtained 
in a state of considerable purity by pressing the stearine of frozen oil between layers of bibulous paper, and 
then squeezing the paper under water, when the Elaine collects upon the surface. In this state of purity it 
is peculiarly fitted for greasing the wheels of watches, and other delicate machinery, since it does not thicken 
or become rancid, by exposure in the air, and requires a cold of about 20° F. for congelation. 
The olive is remarkable for containing a fixed oil in the pulp of its fruit. Fixed oils are almost inva- 
riably confined to the seeds of plants, as in the poppy, almond, linseed, rape seed, &c., &c., the drupes of 
the olive and the melia being perhaps the only exceptions. 
Adulterations. — Olive oil is said to be sometimes adulterated with poppy oil, though such an occur- 
rence is probably rare in this country. Four methods, however, have been proposed for detecting the 
fraud ; and as they have reference to some characteristic properties of olive oil, they deserve notice. The 
first is the beading: if we shake pure olive oil in a phial half filled with it, the surface of the oil soon be- 
comes smooth by repose ; whereas when poppy oil is present, a number of air-bubbles (or beads, as they 
are termed) remain. The second method is by congelation , — olive oil more readily congealing than poppy 
oil. The third method is that founded on the conducting power of the oil for electricity. The fourth method 
is by nitrate oj mercury. If recently made nitrate of mercury be mixed with twelve times its weight of pure 
olive oil, and the mixture strongly agitated, the whole mass becomes solid in the course of a few hours. 
With poppy or other oils, the nitrate of mercury does not form a solid compound, and therefore when they 
are mixed with olive oil, we judge of their presence and quantity by the degree and quickness of solidification 
of the suspected oil. 
Medical Properties and Uses. — The medical properties of olive oil are those of a demulcent, 
emollient, and laxative. In catarrh and other pulmonary affections, it has been used as a demulcent, in the 
form of emulsion : but the oil of almonds is more generally employed. It is occasionally recommended to 
be internally administered for worms ; and to lubricate, and sheath, the mucous membrane of the stomach, 
from the action of acrid poisons, particularly of cantharides. From the experiments, however, of Dr. Pallas, 
repeated by Orfila, it appears that oil possesses the property of dissolving the active principle of cantharides, 
and augments the danger instead of preventing it. And Dr. Whiting has shewn satisfactorily in a com- 
munication made to the Medico-Botanical Society of London, that its admixture in small quantities with 
morphia, renders the peculiar affects of that medicine more regular and certain. At one time it was sup- 
posed to possess antidotal properties for arsenical poisons ; and Dr. Paris tells us, that the antidote on 
which the men employed in the copper smelting works and tin burning-houses in Cornwall, rely with con- 
fidence, “whenever they are infested with more than an ordinary portion of arsenical vapour, is sweet oil, and 
an annual sum is allowed by the proprietors, in order that it may be constantly supplied.” There is, how- 
ever, no reason to believe that its agency is more than mechanical. It is applied externally to prevent the 
contagious influence of the plague. Mr. Jackson, in his History of Morocco, narrates many individual cases 
of its success, even after infectious symptoms had manifested themselves ; and as his veracity cannot be 
impeached, his advice in the absence of better treatment, is entitled to attention, although the French 
physicians do not appear to rely much upon its virtue. The application should be by long continued 
friction ; and when successful, it is followed by profuse and general perspirations, that are said to afford 
immediate relief. In Malta the frictions with oil were found beneficial only in the first and last stages of 
the disease ; but were of no advantage when it was at its height. The internal and external use of olive 
oil was formerly celebrated for the bite of the viper, rattlesnake, and other venemous serpents ; though little 
reliance is now placed in it. The use of it, as a condiment, and in the arts, is too well known to require 
any comment. 
Besides these, there are other medicinal uses to which olive oil has been applied, but which it is 
sufficient merely to allude to. Such are, the internal exhibition of large quantities of it in arthritic pains, — 
the employment of oil frictions in dropsy, and the anointing the body with warm olive oil as a preventive of 
plague. 
Lastly, we may mention the extensive use made of olive oil in various ointments, cerates, liniments 
and plasters. 
Dose and Administration. — As a laxative, the dose is one or two fluid ounces. As an emollient 
and demulcent, it is sometimes taken in the form of an emulsion, made with either alkali or gum. 
