Rape-cake of good quality possesses a dark-green color (the greener the better), and when broken exhibits a mottled aspect--yellowish and dark-brown spots. Sometimes a tolerably good specimen has a brownish color; but the German and Danish cakes are always of a greenish hue. The odor is stronger than that of linseed-cake, and differs but little from that of rape-oil. The only serious adulteration of rape-cake is the addition to it of mustard-seed--sometimes accidentally--less frequently, as I believe, intentionally. This sophistication admits of easy detection. Scrape into small particles about half an ounce of the cake, add six times its weight of water, form the solid and liquid into a paste, and allow the mixture to stand for a few hours. If the cake contain mustard the characteristic odor of that substance will be evolved, and its intensity will afford a rough indication of the amount of the adulterant. As some specimens of genuine rape-cake possess a somewhat pungent odor, care must be taken not to confound it with that of mustard; but, indeed, it is not difficult to discriminate the latter. The paste of rape-cake which contains an injurious proportion of mustard, has a very pungent flavor. Rape-cake improves somewhat if kept for say six months; but old cake is worse than the fresh article. _Cottonseed Cake_ is one of the most valuable feeding stuffs that have come into use of late years. Its chemical composition shows it to be about equal to that of the best linseed-cake, and as its price is much lower than that of the latter, it may be fairly considered a more economical food. These remarks apply only to the shelled, or decorticated seed-cake, for the article prepared from the whole seed is of very inferior composition, and should never be employed. The use of the cake made from the whole seed has proved fatal in many instances, not from its possessing any poisonous quality, but in consequence of its hard, indigestible husk, accumulating in, and inflaming, the animal's bowels. The composition of this cake varies somewhat. The following analysis of a sample from one of the Western States of North America, imported by Messrs. G. Seagrave and Co., of Liverpool, was made by me:-- COMPOSITION OF DECORTICATED COTTON-SEED CAKE. Water 8·20 Oil 10·16 Albuminous, or flesh-forming principles 40·25 Gum, sugar, &c. 21·10 Fibre 9·23 Ash (mineral matter) 11·06 ------ 100·00