In India, rape-seed is very commonly sown mixed with mustard-seed, and almost always as an auxiliary with grain crops. It prefers kerns, and does not flourish on clay soils. The sowing takes place in October, and the harvest in the following February, the plants being cut somewhat prematurely, or the pods would burst, and much of the seed be lost. The latter is ripened by exposure to the sun for 3-4 days on the threshing-floor, and is then easily dislodged.
The yield of seed per acre, and of oil from the seed, vary exceedingly, principally according to the soil, the season, and the care bestowed. Rotation of crops is as necessary for this as for every other culture. A crop that stands well and thick on the land does not always yield the most oil. In France, the seed is estimated to average 20 bush, an acre and often exceeds that figure; and the product of oil is calculated at 50 lb. (unrefined) from 22 gal. of seed. There are no available statistios showing the seed-crop per acre in India ; hut the Indian seed known as " Guzerat rape," largely crushed at Dautzig, is found to yield 31 per cent, more oil than European seed, and leaves a cake richer in fatty matters and albuminoids ; it is shipped from Bombay, and brings the highest price of any.
In France, colza-culture extends throughout the regions of the north-west and the plains of the north, but is little known in the south, and in the mountains of the centre. The chief departments engaged in raising this crop are Pas de Calais, Calvados, Seine-Inferieure, Nord, Somme, Saone-et Loire, and Eure. The industry is declining before the extensive imports of mineral oils from America. In 1873, there were 415,491 acres under the crop, which yielded 6,541,718 bush, of seed ; and in 1877, 344,187 acres afforded 5,992,591 bush. of seed. Considerable quantities of rape seed are produced in Germany and Belgium, and much is imported in addition. The expression of the oil forme a large industry at Dantzig and Stettin. The former crushed 12,500 tons of rape seed in 1879, exporting 88,000 cwt. of oil ; of this, 2600 cwt. refined and 35,000 cwt. crude were exported to England. The total exports in that year were 92,833 cwt., value 127,650/., as against 77,922 owt., 124,675/., in 1878. Memel shipped 2532 cwt , value 1266/., in 1879. A greet deal of
rape-seed is grown in Hungary, but the area sown varies remarkably. During the years 1854-77, the annual production has fluctuated between 6300 and 123,900 tons of seed, averaging 38,882 tone ; the crop of 1877 amounted to 100,000 tons. In the countries bordering the Danube, colza grows both wild and under cultivation. The shipments of seed from Roumanian (Danube) ports increased from 52,882 quarters in 1874 to 86,754 in 1879 ; in 1877, they were only 16,065 quarters (wild) ; in 1878, 117,297. The exports from Galatz in 1879 were 4087 quarters. Denmark exhibits a down ward tendency in the cultivation of this crop, the number of acres occupied by it being 35,330 in 1866, and 1272 in 1876 ; the production in 1878 had fallen to 23,000 bush. Quantities of rape-seed are exported from Russia ; the shipments in 1879 were 69,153 quarters from Nicolaieff, 71,572 from Taganrog and Rostov, 15,712 from Mariopol, 5149 from Yeisk, and 255 from Genitchesk. Wild rape is dying out in the Nicolaieff district, and being replaced by cultivated. The produce is shipped chiefly to N. France. The rape-crop is very general throughout India, and ie growing in importance, the shipments of seed having increased from 359,854 cwt. in 18734, to 3,193,488 cwt. in 1877-8. The Chinese district of Ichang produces large quantities of colza-oil.
Colza- or rape-oil has a sp. gr. of 0 .912-0. 920, and congeals at-6° (21°F.); its colour is brownish yellow, and it acquires a nauseous odour and flavour by keeping. It consists of 54 per cent. oleine and 46 per cent. stearine ; as extracted, it contains much mucilage, which is removed by treatment with 2 per cent. of sulphuric acid ; this operation diminishes the colour and density of the oil. As the purified oil ages, it becomes whiter and more viscous, and increases in density, at the same time losing its combustibility, and burning with a most unpleasant smoke ; it is very slightly soluble in alcohol, and is itself a solvent of sulphur and phosphorus. Formerly, the chief applica tion of the oil was for illuminating purposes, and it is so still in India ; but in Europe, it is used as a lubricant, and ie employed extensively by indiarubber manufacturers.