508 A FOREST TOUR AMONG THE DUNES OF GASCONY. 
ordinary temperature of the air; and spirit of turpentine, which 
is liquid and volatile, and some of which is lost if the caldron is 
over-heated. These two substances are separated by distillation 
in the following manner:—The liquid resin is allowed to run 
through a strainer into a retort, a small quantity of water being 
introduced at the same time. The rising steam carries the spirit 
of turpentine with it, and both are, after passing through a 
refrigerator, caught, in a liquid form, in a trough placed to 
receive them ; the spirit, being lighter than the water, lies over it, 
and is easily drawn off. The colophany is then allowed to 
run out of the retort, and passing through a sieve, is caught 
in a vat below. Thence it is poured into flat metal dishes, and 
allowed to harden in the sun, under which process the finer 
qualities attain a delicate amber colour. But there are several 
classes of this substance, distinguished chiefly by their colour, 
which is a guide to their degree of purity, and these are known 
by various names, and have different commercial values. The 
impure residue left in the caldron is distilled separately, and 
yields rosin and pitch. The raw resin collected from the trees in 
the autumn is harder and less valuable than that obtained during 
the spring and summer. 
We were told that, at the factory, 25 barrels (of 520 lbs.) of 
raw resin are distilled per diem in summer, and 16 in winter. 
The spirit of turpentine sells for 24s. per 100 lbs., and the 
colophany for 9s. per 100 Ibs.; but the purer kinds, for the 
manufacture of which only the most liquid portions of the raw 
resin are put into the caldron, fetch from 13s. 6d. to 14s. 6d., 
the price of the finest quality, known as Venice turpentine, 
rising to £4, 10s. per 100 lbs. Comparatively small quantities 
only of the finer substances are extracted. 
UTILISATION OF THE WoopD AND SUBSTANCES EXTRACTED 
FROM THE PINE TREES. 
The effect of tapping the pine is to cause a flow of resin towards 
the lower portion of the stem, which thus becomes charged with 
that substance, and is rendered harder and more durable than the 
upper part of the tree. The resinous wood is used for various 
purposes: very largely for railway sleepers, when it is injected 
with creosote or sulphate of copper. We visited a factory at 
Labouheyre, in which the latter substance is used for injecting 
