318 
BALSAM.--POPLAR. 
cum, formerly called Amyris Zeylanica, will grow 
with us to the height of 30 feet, and is propa- 
gated from cuttings in peat and loam. 
BALSAM-POPLAR, or Tacavanaca,—botani- 
cally Populus balsamifera. A timber tree of the 
poplar genus. It is a native of North America, 
and was introduced to Great Britain near the 
close of the 17th century. It grows to the height 
of about 70 feet, and has an imposing and even 
majestic appearance. A shoot of it has been 
known to grow ten feet in one summer, with a 
diameter near the base of about an inch. A 
young shoot has five angles; but the bark of 
these angles is so extended by future growth, as 
to leave only traces of the angles in the older 
branches. ‘he bark of the tree is smooth, and 
of a whitish colour. Hanbury, first referring to 
the angles of the young shoots and then noticing 
| the whole tree, says, “This gives the tree in win- 
_ ter a particular look; for at the base of each bud, 
| they curve over and meet. 
Thus there will be 
_ between every bud, formed by the bark, figures 
like niches, as it were, of public buildings, though 
with an upright in the middle, at the top of each 
of which, like an ornament, is seated the bud, for 
_ the future shoot or leaf. These buds are only to 
| be found on the younger branches; but the figure 
is retained on the bark of the older without those 
ornaments. But of all the trees in a collection, 
none more agreeably by its leaves entertains us 
than this, whether we consider their colour, fig- 
ure, or size. Thecolour isa light, shining green, 
which is heightened in the autumn by the strong 
midrib, and the large veins that issue from it, 
turning to a 1ed colour; the lesser veins also 
being in some degree affected, occasions upon the 
same leaf a sweet contrast. Their fizure nearly 
resembles that of a heart; and they are notched 
at their edges. But the chief majesty this tree 
receives is from the size of the leaves. I have 
measured some of the younger trees, and found 
the leaves ten inches long and eight broad, with 
a strong footstalk of four inches in length. These 
majestic leaves are placed alternately on the 
branches, though, as the tree advances in height, 
they diminish in size. This species shoots late in 
the autumn; and these young shoots have their 
ends often killed in hard winters; which is an 
imperfection, as it causes the tree to have a very 
bad look in the spring, before and when the leaves 
are putting out. However, these last will not 
fail afterwards to make ample amends for the 
former defect. The flowers afford no pleasure to 
the gardener; they are only catkins like other 
poplars, and fit only for the curious botanist’s 
inspection.” The balsam-poplar, like most of 
its co-species, sends up numerous suckers from 
its decurrent roots, and is very easily propagated 
either from these suckers or from cuttings. An 
adhesive, strong-smelled resin covers the buds of 
this tree, and gives rise to its name. 
BALSAMS. This term was formerly applied 
to all liquid vegetable resins as well as to many 
BALSAM-TREE. 
pharmaceutical preparations ; but, to avoid con- 
fusion, the French chemists confine the term éal- 
sam to vegetable substances composed of benzoic 
acid with more or less volatile oil. But as this 
would exclude copaiva and some other sub- 
stances, popularly called balsams, most of the 
German chemists retain the old acceptation of © 
the term, and divide balsams into those which | 
do not and those which do contain this acid. To 
the former, which also are called oleo-resins, 
liquid resins, or terebinthinates belong. ‘The dif- 
ferent turpentines (including Canada -balsain), 
copaiva, and opobalsamum or Mecca - balsam, 
are semiliquid resinous or glutinous juices, which 
flow spontaneously or by incisions from various 
vegetables, especially those belonging to the or- 
ders Coniferze, Terebinthaceze, and Leguminose. 
They have a hot and acrid taste, and a strong 
odour, which, in some, is very fragrant, in others 
less agreeable, but peculiar. ‘They consist of a 
volatile oil and resin. Their odour, their semi- 
liquidity, and much of their medicinal activity, — 
are owing to the volatile oil which they contain, 
which may readily be procured from them by dis- 
tillation, and which volatilizes by exposure to air, 
whereby they become hard. From the next, or 
true balsams, they are distinguished by not yield- 
ing benzoic acid. Those balsams which contain 
benzoic acid or balsams, more properly so called, 
are solid, soft, or liquid substances, according to 
the quantity of volatile oil which they contain; 
they have an aromatic, usually agreeable odour, 
and a warm acrid taste. They dissolve in alco- 
hol, and the solution, when mixed with water, 
becomes milky, owing to the precipitation of 
resin. By sublimation, as well as by other 
methods, they yield benzoic acid. They owe 
their principal medicinal activity to the con- 
tained benzoic acid. They are obtained princi- 
pally from the orders Styraceze, Leguminose, 
and Balsamaceze. To this class belong benzoin, 
styrax, tolu, Peruvian balsam, and liquid amber. 
The natural production, called Chinese varnish, 
belongs also to this class. 
BALSAM-TREE,—botanically Clusia. A genus 
of tender, evergreen, ornamental trees, of the | 
guttiferous tribe. Four species have been intro- 
duced to the hot-houses of Great Britain ; and 
about a dozen more have been described by botan- 
ists. The rose-coloured and longest known species, 
Clusia rosea, is a native of Carolina and the West 
Indies, and usually grows to the height of about 
30 feet. It sports itself into numerous seminal 
varieties, with different colours and sizes of both 
flower and fruit. Its stem ramifies on all sides 
into numerous branches; its leaves are single, 
round, and succulent, and occur in pairs, or op- 
posites; and its flowers have thick succulent 
covers, and are produced at the ends of the branch- 
es. A balsam resembling turpentine exudes 
from every part of this tree, and has been much 
used as a plaster for the cure of sciatica. The 
West Indians call this balsam hog-gum, from a 
