VEGETABLE OILS.J 



UNDTJLATORY FORCES. LIGHT. 



105 



twenty-four per cent, of oil It is too expensive for 

 lamps, though its flame is very brilliant, and its other 

 qualities are remarkably good. 



(c.) Rape oil is extracted from the seeds of several 

 species of brassica (the cabbage and turnip tribe), as the 

 Brassica oUracea, campestris, napus, <fcc. ; all of which 

 are cultivated in this and other countries for the oil 

 which they yield. In France a very superior rape oil, 

 termed colza oil, is obtained from a variety of Brastica 

 eampestrif, named oleifera. In every case the oil is 

 procured by crushing or grinding, and pressing the seed 

 in the way already described, and it is refined by the 

 addition of one or two per cent, of sulphuric acid. The 

 seeds yield from twenty-eight to thirty per cent, of oil. 

 Host of the rape oil employed in this country is ex- 

 pressed here. Occasionally we receive small shipments of 

 the oil from Belgium, France, and the East Indies ; but by 

 far the larger proportion is obtained from the seed itself, 

 of which we import large quantities. Mr. Brotherton, 

 who is a large oil-presser, states, that good English- 

 grown rape yields the best kind of oil ; and he recom- 

 mends this fact to the notice of agriculturists, saying 

 that as much as five quarters of seed, worth fifty shillings 

 a quarter, may be obtained from an acre of laud. 



Rape oil is extensively used for illuminating purposes, 

 both here and on the continent : in fact, it is now the 

 usual lamp-oil of commerce. Its properties are but 

 little inferior to those of sperm ; and the only objection 

 that can be urged against it is, that after it has once 

 been heated in the lamp it is apt to thicken and to clog 

 the wick. Colza oil is generally consumed in the Carcel 

 or French lamp; but it has no very great advantages 

 over the commoner kinds of rape oiL The crude or raw 

 oil is not suited for such purposes, on account of the 

 mucilage which it contains : it is of a greenish-brown 

 colour, and ha* somewhat the odour of linseed oil ; but 

 when it is refined it loses both of these objectionable pro- 

 perties, and becomes as pale and limpid as sperm. 



(d.) Cocoa-nut oil is the produce of the Cocoa nucifera, 

 or common cocoa-nut palm ; the fruit of which is decor- 

 ticated, crushed, heated, and pressed. We have already 

 stated that the oil is imported into this country in a 

 buttery or tallow-like condition ; and that after sub- 

 mitting it to pressure between warm plates, the liquid 

 oil runs out, leaving the cocinine or cocoa-nut stearine 

 for the manufacture of candles. The elaine or oleine of 

 palm od may be obtained in a similar way ; and both of 

 the oils may be purified by means of common sulphuric 

 acid. Cocoa-nut oil has rather a pleasant odour, and it 

 burns exceedingly well in lamps, provided it is not ex- 

 posed to too low a temperature ; for it is apt to congeal 

 by cold. 



(.) ijettamum or Gingilie oil is procured from the 

 Settamum orientate, of which there are several varieties 

 cultivated in India for the oil which they yield. These 

 are the tuffed-til. or white-seeded variety; the AVi' 

 or party-coloured ; and the tillee, or black. It is from 

 the latter that the oil is chiefly obtained. A large quan- 

 tity of the oil and seed is imported into this country, and 

 into France for the purpose of adulterating other oils ; 

 but in India it is used very extensively as an article of 

 diet, and also for lamps. The oil is extracted and refined 

 in the usual way. 



(/.) Ground-nut oil is obtained in large quantity from 

 the ground-nut or seed of the Bhoe moong (Araehii 

 hypoyaa), a plant that is pretty extensively cultivated in 

 various parts of India. The seeds furnish about forty- 

 four per cent, of a clear pale-yellow oil ? which is largely 

 used as food and for lamps. Two varieties of the plant 

 are cultivated in Malacca namely, the white seed and 

 tlie brown, both of which yield a very good oil About 

 eighty or ninety tons of this oil are imported into this 

 country every year. 



(</.) Common nut oil is derived from two sources 

 namely, the Corylut avellana, or common hazel-nut ; and 

 the Juylan* regia, or common walnut. The former pro- 

 duces about half its weight of oil, and the latter alxjnt 

 bii>--third. The oil is not much used for lamps on ac- 

 oount of it* energetic drying properties : indeed, it is 



VOL. i. 



more apt to resinify and clog the wick than linseed ; but 

 it is largely employed for adulterating other oils. 



(h.) Poppy oil is procured from the seeds of several 

 species of poppy, as 1'apaver somni/erum, bracteatum, 

 orientale, <tc. The plant that yields the largest amount 

 of oil, and which is usually cultivated for this material, 

 is a variety of the somniferum, named nigrum, from the 

 black colour of the seeds. Large quantities of this oil 

 are expressed every year for the purpose of adulterating 

 other oils. It is clear, sweet, limpid, and almost colour- 

 less ; but the great objection to its use as a lamp-oil, is 

 its disposition to dry. 



(i.) Liineed oil is extracted from the seeds of the flax 

 plant (Linum usitatixsimum), which yield from twenty- 

 two to twenty-seven per cent, of oiL If the seeds be 

 crushed and pressed at an ordinary temperature, they 

 yield not more than eighteen or twenty per cent. ; but 

 the oil is of a pale colour, and is thought by some to be of 

 superior quality to the hot-drawn. A large quantity of 

 linseed is cultivated in this country, but the great bulk 

 of the seed used by the oil-presser is imported. The 

 seed is crushed, ground, and pressed in the usual way ; 

 and the oil is refined by means of dilute sulphuric acid. 

 Linseed oil is not usually burnt in lamps, on account of 

 its drying properties ; but if the wick be changed every 

 day, and no more oil is placed in the lamp than is 

 necessary for one night's consumption, it will be found 

 to burn very well, and to 'give a very clear light. By 

 boiling or heating, it acquires increased consistence, and 

 is then more apt to dry. 



(k.) Hemp-teed oil. This oil is produced from the 

 Indian hemp (Cannabis tativa), the seeds of which yield 

 about one-third their weight of oil. The oil has a 

 disagreeable smell, and is not much employed for illu- 

 minating purposes, except by the poorer classes of India. 



(I.) Camel ine or Dodder oU is extracted from the seeds 

 of the Camctina saliva, a plant that grows abundantly 

 in Canada, where the oil is used as a common lamp-oil 

 It is also employed for the same purpose in several parts 

 of Germany. 



(m.) CoHvn-ttfd oil is thought to be as good as rape 

 for lighting purposes: indeed, small quantities of the oil 

 have been expressed for several years past, and used in 

 this way ; but the value of the material has not been 

 fully realised until within the hut few years. At the 

 Exhibition of 1851, specimens of the oil and cako 

 were shown by Mr. Burn of Edinburgh, and by M. De 

 Gt'iiiiny of Marseilles, to both of whom prize- medals 

 were awarded. It appears that, as early as 1785, the 

 importance of this material was perceived by the Society 

 for the Encouragement of Arts and Commerce, for they 

 offered a prize for its manufacture on a large scale ; but 

 it does not seem to have been taken up extensively, 

 perhaps because of the difficulty in purifying the oil. 

 It has, however, been extracted for some time in India, 

 America, and Egypt. Of late years the oil has attracted 

 attention, and means have been devised for its purifica- 

 tion. This is of importance, for very large quantities 

 of cotton-seed are destroyed every year : in fact, more 

 seed is always produced than is required for the next 

 year's crop, and hitherto this excess has been thrown 

 away as useless. At present it is exported to this country, 

 or to France, where it is crushed and pressed. Mr. Burn 

 of Edinburgh, and M. De Geminy of Marseilles, have 

 ! each large mills for the expression and purification of 

 the oil. When first expressed it lias a dirty-brown 

 colour; but, by rectification with sulphuric acid, it 

 becomes clear, and assumes a pale amber tint, in which 

 condition it is well suited for combustion in lamps. The 

 botanical name of the plant which furnishes the seed is 

 Gossypium herbaceum. It is cultivated in India, Syria, 

 Asia Minor, along the Mediterranean, and in America. 



(n.) Mustard oil. This is procured from the dross or 

 siftiugs of black and white mustard-seed (Sinapis alba 

 and Sinapit nigra), both of which are cultivated very 

 extensively in this and other countries, for the manu- 

 facture of mustard-flour. The siftings furnish about 

 forty per cent, of a dark-brown oil; the seeds themselves 

 yield from eighteen to thirty-six per cent. In India an 



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