Rape, or Coleseed, Brassica Napus, L. a valuable indigenous plant, of the uses of which we have already given a concise account, vol. i. p. 413 : - we shall, therefore, add a few particulars relative to its culture, etc, to render our statement more complete.
This plant is cultivated princi-pally for the purpose of expressing the oil from its seed, by which it is also propagated : - the best kind of the latter should be large and black ; it ought to be sown in the month of June (in the proportion of 2lbs, per acre, broad-cast), with the two fore-fingers and thumb, to prevent it from shooting up in patches : it may likewise be drilled, at the dis-H h 4 tancc tance of 12 or 14 inches apart. Sometimes rape and turnips are sown together ; but such practice is not economical; as the two crops mutually injure each other.
Rape yields most abundantly after beans, turnips, or cabbages ; the soil being previously ploughed twice, north and south, for the better reception of the solar heat ; and, if transplanted, such plants will vegetate with uncommon luxuriance, so as amply to repay the ad - ditional expence. For this purpose, Mr. Hazard (Letters and Papers of the Bath and West of England Society, etc. vol. iv.) recommends one rood to be sown in the middle of June, and to remove the young plants towards the middle of August, into ridges twofeet apart, and •at the distance of sixteen inches from each other. As soon as they have taken root, and begin to shoot up, it will be necessary to manage them by the horse or hand-hoe; and to draw the earth around their stems. A rood of land, thus sown, will, according to his experience, produce a sufficient number of plants for the stocking of ten acres ; and in the following spring the leaves may be fed off with sheep; because new ones will immediately succeed. But, as these tender plants are much infested by slugs, which devour them with avidity, it will be advisable to scatter ever them a mixture of slaked lime and wood-ashes, in the proportion of 10 bushels of the former, to 15 of the latter, per acre.
Rape-seed attains to maturity from July to September; and, as it is easily shed, the plants are generally cut with sickles ; laid on the ground to dry; and the seed is rubbed out on a large cloth spread in the middle of the field, whence it is conveyed to the mill. The oil which these seeds yield by expres-sion, is employed for various use-ful purposes in domestic life, and particularly for burning in lamps ; but, as it is apt to become rancid, M. ThenaRd has published the following practical method of puri-fying it. He directs 1 1/2 or 2 parts of concentrated sulphuric acid to be added to 100 parts of oil, and the whole to be perfectly incorporated by agitation : the fluid imme-diately becomes turbid, assuming a dark-green cast ; and, in the course of three quarters of an hour, the colouring particles begin to collect in lumps. The agitation must now cease ; and double the weight of oil of vitriol, diluted with pure water, should be added : in order to mingle these different ingredients, the stirring ought to be renewed for the space of half an hour; after which the whole may be left to settle for seven or eight days. At the end of that time, the oil will be found on the surface ; on being gently drawn, off, and filtred through cotton or wool, it will be almost entirely divested of colour, smell, and taste ; so that it will burn clear, without any interruption.
The refuse of rape, after express-ing the oil, is known by the name of rape-cake ; the economical uses of which we have already stated, vol. i. p. 413.- The whole plant is of great service in feeding cattle ; and, after the seed is threshed, the straw and chaff, on being burnt, afford ashes equally valuable as the best pot-ashes.
Lastly, if rape-straw be strong, it may be advantageously employed for inclosing fences in farm-yards ; and, with still greater profit, for littering straw - yards, cow-sheds, or other receptacles for stall - fed cattle.