EXTRACT. 
235 
thickness of ten or twelve inches in diameter, that it is worth while 
to collect the turpentine; and from that time for forty or fifty years, 
if it continue so long in vigorous growth, the tree will continue to 
yield annually from seven to eight pounds of turpentine. 
All the turpentines totally dissolve in rectified spirit, they become 
miscible with water into a milky liquor, by the mediations of the 
yolk or white of an egg, and more elegantly by mucilages. Distilled 
with water, they yield a subtile penetrating essential oil, vulgarly 
called spirit of turpentine, a yellow or blackish resin remaining in 
the still which is the common resin of the shops. The essential oil, 
on being distilled in a retort, becomes more subtile and in this state 
is ethereal oil of turpentine. 
The turpentines stimulate the first passages, and prove laxative; 
and we are told by Dr. Cullen, that half an ounce of Venice turpen¬ 
tine, triturated with the yolk of an egg, and diffused in water, may 
he employed in the form of an injection, as the most certain laxative 
in colics, and other cases of obstinate costiveness. When turpentine 
is carried into the blood vessels,it stimulates the whole system ; hence 
its use in chronic rheumatism and paralysis. It readily passes off by 
urine, which it imbues with a peculiar odour; also by perspiration, 
and probably by exhalation from the lungs; and to these various ef¬ 
fects are to he ascribed the virtues it may possess in gravelly com¬ 
plaints, scurvy, and pulmonic disorders. In all these diseases, how¬ 
ever, and especially the last, this medicine, as well as some of the 
gums and balsams of the terebinthinate kind,by acting as stimulants, 
are often productive of mischief, as was first observed by Boerhaave, 
and since by Fothergill. 
The essential oil, in which the virtues of turpentine reside, is not 
only preferred for external use, as a rubifacient, &c. but also inter¬ 
nally as a diuretic; and by Pitcairne and Cheyne, as a remedy for 
the sciatica; but few stomachs are able to bear it in the doses they 
direct. Turpentine, so much used formerly as a digestive applica¬ 
tion, is in modern surgery, almost wholly exploded. 
Besides this well known product, the Larch yields also a manna 
and a gum. The manna is found in the south of France, and is 
called the Marine de Briancon ; it is white, concrete, and sweet, like 
fine new honey. It is rare, and met with only in small drops, so 
that it would be very difficult to collect a pound of it. The drops 
are more or less hard, and adhere to the leaves. Mons. Villars hav¬ 
ing made some enquiries relative to this substance, with Mons. 
Guettard, in the year 1773, found it at sun rise almost fluid, and 
picked up drops of it on the turf, exactly like those which remained 
