and they have
been known to cause intense inflammation of the bowels of animals fed
upon oil-cake, of which they composed but a small proportion. Amongst
the adulterations of linseed-cake, which lower its nutritive value
without imparting to it any injurious properties, are the seeds of
the cereals and the grasses, bran, and flax-straw. Little black seeds
belonging to various species of _Polygonum_, are very often present
in even good cakes; they are very indigestible, but otherwise are not
injurious. Rape-cake is stated to be occasionally used as adulterant
of the more costly linseed, but I have never met with an admixture of
the two articles.

The only way in which a correct estimate of the value of linseed-cake
can be arrived at is by a combined microscopical and chemical analysis;
but as the feeder is not always disposed to incur the cost of this
process, he should make himself acquainted with the characteristic
of the genuine cake, in order to be able to discriminate, as far as
possible, between it and the sophisticated article. I will indicate a
few of the more prominent features of cake of excellent quality, and
point out a few simple and easily-performed tests, which may serve
to detect the existence of gross adulteration. Good cake is hard, of
a reddish-brown color, uniform in appearance, and possesses a rather
pleasant flavor and odour. The adulterated cake is commonly of a greyish
hue, and has a disagreeable odour. A weighed quantity of the cake--say
100 grains--in the state of powder should be formed into a paste with
an ounce of water; if it be good, the paste will be light colored,
moderately stiff, and endowed with a pleasant odour and flavor. If the
paste be thin, the presence of bran, or of grass seeds, is probable.
The latter are easily seen through a magnifying-glass; indeed, most
of them are readily recognisable by the unassisted eye: they may,
therefore, be picked out, and their weight determined. Sand--a frequent
adulterant--may be detected by mixing a small weighed quantity of the
powdered cake with about twelve times its weight of water, allowing the
mixture to stand for half an hour, and collecting and weighing the sand
which will be found at the bottom of the vessel employed. If there be
bran present it will be found lying on the sand, and its structure
is sufficiently distinct to admit of its detection by a mere glance.
There are a great variety of linseed-cakes in the market, of which
the ho