Not only for light, but also for food and manure,
is the colza plant valuable to the world. Cattle
fatten on it, and ground fattens on it; and the
Abbé de Commerel, the introducer to the French
Agricultural Society in 1789 of this chou à
faucher—"mowing cabbage," as he calls it—
was a greater benefactor to mankind than he
dreamed of. Colza cabbage may be said to have
been one of the agents of civilisation.

Then there is laurel oil, or "the oil of bays,"
got from the berries of the bay-tree (Laurus
nobilis) principally from Italy and the south of
Europe generally; the greater part being
shipped from Trieste; and which our doctors
and veterinary surgeons use as a stimulating
liniment for sprains and bruises, and in paralysis.
Is it one of the ingredients of the famous nine
oils? Also the native oil of laurel or laurel
turpentine, imported from Demerara, and got by
making incisions in the bark of a large forest
tree called by the Spaniards Azeyte de sassafras,
and growing in the forests between Orinoco and
Parime. These incisions yield a pale yellow oil,
smelling something between turpentine and oil
of lemons, and easily dissolving caoutchouc. The
Valeria Indica, a Malabar tree, gives "piney tallow
oil," if the fruit is boiled in water and the fat
skimmed from the top. It is white and smells
pleasantly, makes good soap and candles out in
its native place, but is little known, and less used,
here. Then our spindle-tree gives us an oil as
well as butchers' skewers: an oil yellow and
thick, bitter and acrid to the taste, and in odour
like colza; and the beech-tree has nuts good for
feeding pigs, but better for the twelve per cent
of oil to be expressed from them—a clear oil,
thick, inodorous, and pale-yellow in colour, used
in France for both light and cooking, and in
Silesia, by the peasants, in the place of butter.
And there is the oil of mustard-seed, good for
soups and cooking; and tel oil, or the oil of the
Sesamum Orientale, called "oily grain" in South
Carolina, and used for soups and puddings like
rice, the oil coming in for salads, and, indeed,
being often mixed with olive oil: the oil of Behen,
already spoken of; rapeseed oil—the ordinary
English rape, which is the best—used for lighting,
for the manufacture of soft soaps, in the
preparation of leather, and for oiling machinery;
plum-kernel oil, tasting like the oil of sweet
almonds, transparent, and of a brown-yellow,
soon turning rancid, but much liked in Wurtemberg
for lighting purposes; and the "butter of
cacao," had from the nuts of the Theobroma
cacao, when crushed in hot water, and had to
the extent of fifty per cent. It is yellow, but
can be melted white in hot water; smells and
tastes like the cacao-nut; is of the consistency
of suet, and keeps long fresh without turning
rancid. And, lastly, there is the "butter of
nutmegs," prepared by beating the nutmegs to a
paste, steaming them, and then pressing them
between heated plates. This butter is imported
in oblong cakes covered with leaves and looking
like common bricks, of an orange colour,
firm consistency, aromatic and fragrant in
odour, like the nutmegs themselves—when not
wooden. A spurious article is sometimes made
of animal fat boiled with powdered nutmegs
and flavoured with sassafras; but it can be
easily distinguished by the wary. All these
are the non-drying oils, good for food and light,
the oils which, as they grow old, get thicker,
less combustible, offensive to the taste and
rancid, irritating the throat in consequence of
the acid that is developed in them. But that acid
can be removed by boiling rancid oil in water,
with a little magnesia, for a quarter of an hour,
or until it no longer reddens the litmus paper.

Now we come to the drying oils, those which
go chiefly to make painters' varnishes, which dry
up into a transparent, yellowish, flexible
substance, with a skin formed over the surface of
the oil, by which all alteration of its condition
is stopped. When boiled with litharge, or oxide
of lead, they become even more drying, as every
painter, fond of experiments, knows; and if
one-eighth of resin is added to the process it
greatly improves the look of the painting when
dry. First, there is linseed oil, which makes
printers' ink when it has been burned and
mixed with one-sixth of its weight of lamp black,
which is a final dressing to thin gummed silks,
which varnishes leather and oilcloth, and which,
when thoroughly expressed from the seeds, leaves
"oil cake" for cattle-feeding and the destruction
of pleasant milk and butter. Then there is
walnut oil, an even more rapidly drying oil than
linseed, used chiefly for paints and varnishes, and,
because it gets white by age, for white paints;
and hazel-nut oil; and poppy oil, from the seeds
which have none of the narcotic properties of
the capsules whence we get the laudanum, the
seeds being sold for birds under the name of
maw-seed, and quite harmless. The oil is like
olive oil in look and taste, and is used to
adulterate it; when treated with litharge or
subacetate of lead, it is used for paints—without
such treatment, for lighting. Hempseed feed
birds, and give a capital oil for varnishes; also
sometimes used for lighting, but not often or
satisfactorily, for it makes a thick edge and clogs
the wick; it does better in the soft soap and
paint manufactories. Sunflower oil makes soap;
it is sometimes used for food, and sometimes
for lighting, but chiefly for soap. Grape-seeds
have an oil which must not be confounded with
the fusil oil obtained in the rectification of
spirits, whether from grape or corns, for the one
is bland and insipid, inodorous, and sometimes,
in the south, used for food, and the other is
simply disgusting, but largely used for confectionary.
And there is the oil of belladonna, which
is used in Wurtemberg for lighting and cooking
limpid, golden-yellow, insipid, and inodorous,
with all the poisonous principles left in the
residual cake, which cannot, therefore, be used
for cattle-feeding, as other more harmless
residual cakes, and the expression of which
stupifies the workmen employed. And there is
tobacco-seed oil, limpid, green-yellow, and
inodorous, and with no more of the narcotic
principles of the plant than poppy-seed oil. And,
lastly, there is castor-oil, and there is croton oil;