p I 
N U S. 
in Shroplhire, it tnuft have been here much fooner. 
Evelyn alfo mentions two Spanilh or filver firs then 
growing in I-Iarefield-park, Middlefex, belonging to Mr. 
Serjeant Newdigate, that were planted there in 1603, at 
two years growth from the feed, the biggell ot which was 
eighty-one feet high, and thirteen feet in circumference 
below; the length, fo far as it is timber, that is, to fix 
inches fquare, feventy-three feet, in the middle feventeen 
inches fquare; and containing 14.6 feet of good timber. 
Mr. Miller fays, it is fuppofed that moll if not all thefe 
trees in Germany were originally planted there; that 
Tournefort, in his travels, mentions the firs of Mount 
Olympus as the moft beautiful trees in the Levant, and 
that he has received cones from thence upwards of a foot 
in length. 
Though Linnaeus and feveral other writers on the 
Materia Medica refer the common turpentine to the 
Pinus fy 1 veftris, and the Straiburgh turpentine to this; 
yet Murray, following Haller and Duhamel, afcribe the 
common turpentine to the filver fir, which pours it out 
fo freely, that it is feldom neceffary to make incifions 
through the bark for that purpofe. 
It has been cbferved in Ireland, that no tree grows 
fpeedily to fo large a fize as the filver fir. Some at forty 
years growth, in a wet clay on a rock, meafuring twelve 
feet in circumference at the ground, and feven feet and 
a half at five feet high; one containing feventy-fix feet 
of folid timber. It is found to be excellent for boat¬ 
building. A gentleman in Harnpfhire floored his 
library with filver fir frelh cut down, and the boards did 
not contrail in the lead. The earl of Fife alfo remarks, 
that no trees make a greater progrefs than this and the 
larch. ■ 
The following anatomical defcription of the fir-tree is 
from an Effay on the Operations of the Dry Rot, by 
Robert M‘Adam, architect andfurveyor; 181S. 
The longitudinal divifions of this tree, for it appears 
to me doubtful whether they can be called veffels, are 
feemingly of two forts ; and, when viewed at right 
angles to the radiates, they appear like a bunch of dreffed 
flax or hemp, after being fomewhat prefled, fo as to 
render the fibres a little wrinkled. When viewed 
parallel to the radiates, they have the appearance of a 
web of the fame materials, having four or five threads of 
the woof clofe together, as in muflin or cambric, and a 
Ipace rather more than equal to this without any woof, 
flmilar to the fpace between handkerchiefs in the piece, 
where the w-arp only appears without any woof: and thus 
they are continued in alternate bars one over another, 
from the extremities of the filaments of the roots to tliofe 
of the branches. 
The radiates lie along that part which looks as if it 
were woven ; and in many cafes they have the appearance 
of veffels of confiderable dimenfions : but this is only to 
be feen when they are filled with coloured matter, which 
is evidently turpentine. Where this is not vifible, there 
is generally fomething like a very fine dew in miniature 
on the reticular part, ftandingin rows both longitudinally 
and horizontally. The radiates apparently perform the 
fame office as in the oak and other trees. The fort of 
network likewife lies in the horizontal diredlion, and 
breaks the rectilinear perpendicular preffure of the 
juices contained in the longitudinal veffels; if fuch they 
be. At all events it prevents the juice of the tree from 
defcending in a right line, whether contained in 
veffels or in the longitudinal cavities between the 
portions of fibrous matter not connected in a tubular 
form, yet fufficiently clofe together to fupport moifture on 
the fame principle as that ot capillary attraction in tubes. 
If thefe woven flax-like fibres be hollow tubes, it is 
probable that they principally contain the more watery 
matter abforbed by the plant, before chemical union 
takes place ; and they may be prefumed to be formed of 
a film, flmilar to that which loon appears on the furface 
of water when poured on tar. Though after the texture 
483 
of the wood is formed, and the chemical union of the 
different elements of the tree has taken place, it might 
be fuppofed, that the contents of the veffels would be 
coloured matter; yet they are quite tranfparent and 
colourlefs. Still it is difficult to fay, whether the little 
globules, like dew in miniature, which appear in 
beautiful rows, are contained in longitudinal veffels, or 
move along by attachment to the firmly-formed thread, 
now become woody fibre, in a manner fimilar to the 
perfpiration on the hairs of animals. Thefe globules 
which are confiderably tinged with colour, and are, no 
doubt, the blood of the plant, are preffed along the 
woody fibres, as from one piece of network or lodgement 
to another. The other fort of longitudinal veffels, if 
fuch they may be called, are very irregular; and appear 
like a number of the fmall ones ruptured, and combined 
into one, being evidently open all round like a netpurfe. 
They generally contain confiderable quantities of fluid; 
which is fupported by thin and feemingly tough 
membranes. The radiates frequently crofs thefe larger 
veffels; and the general appearance of the blood in them 
both, where they pafs each other, feems to indicate, that 
they communicate together in their paffage. The lon¬ 
gitudinal veffels, however-, appear to contain a much 
greater portion of air than the radiates. Thefe largefl 
longitudinal veffels are generally from one eighth to 
three eighths of an inch apart, on the circular line of the 
plant; and about three of them in the breadth of each 
concentric ring, or year’s growth. In other cafes they 
are much further apart, but they are extremely irregular. 
Sometimes three, four, or five, will occur in a duller. 
Where there is fuch a duller, the turpentine will generally 
be found exhaling from the plant by tilde canals. This 
however is far more common in the filver fir, the 
Weymouth pine, and fome others, than in the Scotch 
fir. 
The chemical analyfis of the w'oody fibre of this plant 
in various experiments has yielded fuch different reiults, 
that I think it unneceffary to mention them. I (hall 
therefore only take notice of the juices, and the procefs 
of their elaboration as they relate to temperature. A 
low temperature appears moll congenial to the fir-tree, 
although it is to be found in very warm climates. 
Yet from the nature of its juices it cannot be expelled 
to arrive at great perfection in a lower degree of north 
latitude than 53°or 54° ; or rather except in a mean tem¬ 
perature that is proportionate to thefe degrees of 
latitude, fay 4.5 0 or 4.6° of Fahrenheit. 
The J'uccus proprius of fir-trees is of a peculiar kind, 
and known by the general name of turpentine , different 
varieties of which are produced by different fpecies of the 
fir. It is obtained in confiderable quantity by boring 
holes, or cutting deep notches, in the trunk of the tree ; 
but more expeditioufly by means of artificial heat, when 
it affutnes the name of tar. To procure this, the wood of 
the trunk, branches, and roots, is heaped together, 
covered with turf, and then fet on fire, fo as to be ex- 
pofed to a fmothering combultion, as in preparing 
charcoal. A gutter is formed at the bottom, to receive 
the turpentine, which flows out ftrongly impregnated 
with carbon, whence the tar acquires its black colour. 
In making pitch from tar by infpiffation after it has 
been imported into this country, the firft produCl that 
diliils over is a brown acid water, mixed with a good 
deal of oil. As the procefs proceeds, and the heat is 
increafed, the acid diminilhes, and the oil increafes. 
According to Aikin, from 600 gallons of tar, or 18 or 20 
barrels, the product will be about 10 barrels of pitch, or 
22 cwt. 176 gallons of oil, and about 40 gallons of acid. 
The oil and water, which are diftilled over, do not again 
inix, fo that they can eafily be feparated by decantation. 
Where the temperature, when this tree is planted, is 
railed above a certain degree, the equilibrium of the com¬ 
pound is dellroyed ; and the oil, being the moft volatile 
of any of the vegetable oils, flies off in the fhape of vapour. 
The 
