Pure and Mixed Linseed-Cakes. 
11 
host of other weed-seeds in the screenings from linseed. The 
preceding list, however, is sufficiently long to show the varied 
character of the weed-seeds in linseed, and affords abundant 
evidence that good and wholesome linseed-cake cannot be made 
from dirty linseed, and that cake which is made from little 
else but linseed-siftings is not food fit for cattle. 
Good linseed-cake, when examined by an ordinary pocket-lens, 
ought to exhibit nothing but crushed linseed. If a hundred 
grains of ground pure linseed-cake are mixed with 4 ounces of 
hot water, and the mixture stirred up occasionally, it will form, 
after an hour's time, a thick jelly, possessing an agreeable taste 
and nice smell. Pure linseed-cake, in good condition, colours 
the water in this experiment only slightly yellow, and the solu- 
tion appears neither acid nor alkaline when tested with Litmus- 
paper. A portion of the powdered cake boiled with distilled- 
water in a test-tube, and allowed to become perfectly cool by plung- 
ing it in cold water, gives no reaction, or only a faint greenish 
colour, on the addition of a few drops of Iodine solution, showing 
the absence of starch in perfectly pure linseed-cake, or the pre- 
sence of mere traces of starchy matter occurring in the farina- 
ceous seeds, which in minute proportions occured in the linseed. 
By these simple means pure linseed-cake can be readily dis- 
tinguished from inferior, mixed, or adulterated cake. 
The composition of equally pui-e linseed-cakes varies con- 
siderably, as will be seen in the following tables, in which are 
grouped together analyses of three species of linseed-cake. 
Table II. contains a selection from a large number of analyses of 
pure linseed-cakes, all very rich in albuminous compounds. 
Table III. gives the analyses of pure linseed-cakes of a fair 
average composition ; and Table IV. shows the composition of a 
number of pure linseed-cakes, comparatively poor in albuminous 
matter. 
In Tables II. and IV., I have introduced the highest and lowest 
proportion of albuminous compounds which I ever found in pure 
linseed-cake ; and have selected the analyses from a large number, 
with a view of exhibitina: the extent of the variations to which 
the composition of such cake is liable. This appeared to me 
desirable, because the question has frequently been asked of me, 
what is the composition of pure linseed-cake ? a question which 
cannot be answered in a categorical manner. Indeed, as Avill be 
shown presently, the fair average proximate composition of pure 
linseed-cake can be closely imitated and obtained by introducing 
into the compound cake carefully selected cheap materials other 
than linseed, some poor and others rich in albuminous matters, 
and feeding materials rich in oil together with starchy refuse 
matter. If, therefore, an analysis of a feeding-cake shows a close 
