THE SILVER FIR. 201 
in wood-engraving. It usually sells at the price of common 
pine timber. 
This, like most of the other species of this tree, is very pro- 
ductive of resin. It yields the Strasburg turpentine of com- 
merce, so named from the extensive produce of the forests 
contiguous to that town. This resinous fluid is collected from 
the small blisters or tumours formed under the outer bark or 
epidermis, and from other exudations of the tree. It is the 
only tree of the tribe that yields turpentine employed in 
the preparation of clear varnishes and artists’ colours; and 
the resinous juice of the tree is manufactured into several 
articles of great efficacy and importance in medicine and 
in farriery. The essential oil of turpentine is the produce 
of this tree, and is much esteemed in cases of strains and 
bruises. 
None of the Conifers spring from the roots when felled, but 
roots of the silver fir have been known, after the removal of 
the tree, to produce annual circles of ligneous matter, increasing 
the diameter of the stump, and forming yearly deposits, which 
have sometimes continued for many years. Around the out- 
side of a stump about two feet in diameter I have counted 
eight very distinct circles of this woody substance, of good 
average breadth, corresponding to the number of summers 
which had elapsed since the tree was felled. The substance 
has a creamy white appearance, as compressible as cork, and 
apparently impervious to moisture. Of the instances of this 
curious formation, the most remarkable is that recorded by 
M. Dutrochet, of a stump of silver fir, felled in the Jura 
forests in 1743, which was still full of life when examined at 
the end of the year 1836. This formation consisted of ninety- 
two layers of woody matter, formed during that number of 
years by the roots, deprived of their trunk and leaves, and 
the wood which composed the stump at the time the tree was 
felled had in 1836 entirely disappeared. 
P. balsamea (Loudon): The Balm of Gilead Silver Fir.— 
This tree was introduced into Britain from America at the 
close of the seventeenth century by Bishop Compton. During 
