234 
EXTRACT. 
a piece of sound, well ripened larch wood, with another piece of sound 
oak wood, in the river Medway, at Rochester Bridge, where it is well 
known that every other kind of wood is very soon perforated by the 
sea worm. In addition to the other valuable properties of this tree, 
Mr. White has communicated to the Society of Arts, the result of 
some experiments decisive of the use of its bark in tanning. While 
some of his workmen were taking off the bark from a number of larch 
trees, intended, for building, they found the nails of their fingers 
stained, which induced him to try whether it would tan leather or 
not. He procured two calf skins, of equal price, weight, and sub¬ 
stance, and immersed one in an infusion of oak bark of very fine 
quality, and the other in the same proportion of larch bark, from a 
very small tree, each skin remaining exactly the same time in its 
respective tan-pit; and, during the operation, he repeatedly weighed 
a measure of larch liquor against the oak, and always found the 
former to preponderate; the consequence was, that the skin tanned 
with larch, felt thicker in the hand and heavier, and was finer in 
the grain, and of a lighter colour, than that tanned with oak. For 
this communication, Mr. White was presented by the Society of 
Arts with a gold medal, in the year 1813. See their Trans. Vol. 
xxi, for that year. It is proper also to observe, that Mr. White’s 
father had received nine gold and two silver medals from the same 
society, for planting those trees, which the son is now converting to 
so valuable a purpose. The resinous juice of the larch tree is the 
turpentine of commerce. It issues spontaneously from the bark, but 
is more commonly obtained by boring a hole with an auger, about 
two feet above the ground, till it reaches near to the heart of the tree; 
into this hole is inserted a small pipe or cock, through which the 
turpentine flows into proper vessels placed for its reception. This 
process is continued from the end of May to the end of September. 
When the trees will yield no more for that season, the turpentine is 
pressed through a cloth to purify it. This is usually thinner than 
any of the other sorts, of a clear whitish or pale yellowish 
colour, a hot, pungent, bitterish, disagreeable taste, and a strong- 
smell, without any of the aromatic flavour of the Chian or Cyprus 
turpentine, obtained from the Pistacia Terebinthus. The common 
and Strasburgh turpentines are from the Pinus Picca; but the 
Canada balsam, which may be considered as the purest of the tur¬ 
pentines, is procured from the balm of gilead and silver firs. 
The turpentine is not to be obtained in considerable quantities 
from very young trees, and in very old ones it gradually dries up, 
ill at last it affords none; it is only after the tree has obtained the 
