_Rape-dust, Mustard, Cotton and Castor Cake._--Rape-dust has long been employed as a manure, and the success which has attended its use has led to the introduction of the refuse cake from some other oil seeds, such as those of mustard and castor-oil, which cannot be employed for feeding. Like the seeds of all plants, these substances are rich in nitrogen, and their ash, containing of course all the constituents of the plant, supplies the necessary inorganic elements. The following are analyses of these substances, which, in addition to the amount of nitrogen and phosphates, shew also that of water and oil, to which reference will be made in a future chapter, in relation to the feeding value of some of them. The detailed composition of their ash may be judged of from that of the seeds from which they are made, and which have been given under that head. +--------------------+------------+-------------+-------------+---------+ | | Rape-Cake. | Poppy-Cake. | Cotton-seed | Castor- | | | | | Cake. | Cake. | | +------------+-------------+-------------+---------+ | Water | 10.68 | 11.63 | 11.19 | 12.31 | | Oil | 11.10 | 5.95 | 9.08 | 24.32 | | Albuminious } | 29.53 | 31.16 | 25.16 | 21.91 | | compounds } | | | | | | Ash | 7.79 | 12.98 | 5.64 | 6.08 | | Other constituents | 40.90 | 38.18 | 48.93 | 35.38 | | +------------+-------------+-------------+---------+ | | 100.00 | 100.00 | 100.00 | 100.00 | | Nitrogen | 4.38 | 4.94 | 3.95 | 3.20 | | Silica | 1.18 | 3.36 | 1.32 | 1.96 | | Phosphates | 3.87 | 69.3 | 2.19 | 2.81 | | Phosphoric acid } | | | | | | in combination } | 0.39 | 3.27 | 0.15 | 0.64 | | with alkalies } | | | | | +--------------------+------------+-------------+-------------+---------+