Ixviii ~=Historical Sketch of the Physical Sciences, 1818. 
pensive, and would leave the camphor in the peculiar semitrans- 
parent state which it is at present required to possess.— 
(See Ann. de Chim. et Phys. vii. 75.) 
7. Action of Alcohol on Oil of Bergamot.—It is a common 
practice with dealers in perfumes to adulterate oil of bergamot 
with alcohol. This induced M. Vauquelin to make a set of ex- 
periments on the action of these two bodies on each other, that 
it might be in his power, when necessary, to detect the fraud. 
The iullawing are the results of these trials. (1.) Oil of berga- 
mot may contain eight per cent. of alcohol of the specific 
gravity 0°817, without its being perceptible when it is mixed 
with water. (2.) When it contains a greater quantity, the sur- 
plus separates, dissolving about 4d of its volume of oil. (3.) A 
small quantity of water, mixed with the alcohol, diminishes 
remarkably its action on the oil; for alcohol of the specific gra- 
vity 0°880 dissolves only =!,th of its volume, while pure alcohol 
dissolves almost half its volume. (4.) When alcohol of the 
specific gravity 0°847 is mixed with oil of bergamot of the 
specific gravity 0°856, the alcohol sinks to the bottom, and the 
oil swims on it. The reason is, that the oil, absorbing a portion 
of the alcohol, becomes lighter, while the residual alcohol, be- 
coming weaker, increases in specific gravity.—(See Annals of 
“Philosophy, xii. 150.) 
8. Oul of Carapa.—This is an oil extracted in Cayenne from 
the fruit of a tree, called carapa by the natives and persoonia by 
botanists. This oil is solid at 39°; it melts when heated to 50° ; 
it has an amber colour, which is more intense when the oil is 
liquid, than when it is solid. This oil has a taste so intensely 
bitter, that it cannot be used for any other purpose than burning 
in lamps. This bitter principle cannot be separated by water, 
alcohol, ether, or acetic acid. Neither is it completely re- 
moved by combining the oil with alkalies —(See Cadet, Jour. 
de Pharmacie, 1819, p. 49.) 
9. Potash.—Dr. Peschier, of Geneva, has pointed out a very 
ingenious way of detecting the presence of potash in vege- 
table juices or infusions, without the necessity of subjecting 
them to incineration. He introduces into the liquid in question 
a quantity of magnesia, and agitates for some time ; the acid 
-(usually carbonic, oxalic, or tartaric) forms an msoluble com- 
“pound with the magnesia, while the alkali, thus set at liberty, 
remains in solution in the liquid, and may be detected by its 
‘ properties.— (Annals of Philosophy, xi. 336.) 
10. Sugar and Gum in Potatoes.—Dr. Peschier has also de- 
tected the presence of mucous sugar, and of gum in the potato. 
’ Hence we see the reason why it undergoes the vinous fermen- 
-tation.—(Iid. p. 337.) bat 
1]. Rice.—Vauquelin made a set of experiments, chiefly with 
a view to ascertain whether rice contained any saccharine mat- 
-ter.; but he was not able to discover ‘any. . He detected a little 
