As to the claims of the plant upon cultivators of oil crops, Dareste estimated the yield to be 1800 kilo. (of 2.2 lb.) per hectare (of 21 acres), while a similar area of oil-palms in the tropics gave only 900 kilo., and of olives in S. Europe 600 kilo. ; the seed was calculated to afford 52 per cent. of oil. Castor-oil has a sp. gr. of 0'969 at (53÷,° F.), 0'957 at 25° (77° F.), and at 94° (204° it has usually a pale-yellow colour, viscid consistence, and slight mawkish odour and flavour, which are much intensified when it becomes rancid ; at-15° (5° F.), it commences to congeal, but does not completely solidify above-18° (0° F.), when it dries np, forming a transparent varnish-like film in three layers ; its boiling-point is 265° (509° F.), when it begins to distil, and affords various products ; it mixes in all proportions with glacial acetic acid and absolute alcohol, and is even soluble in 4 parts alcohol of at 15° (59° F.), and forms a clear mixture with equal weights of the same at 25° (77° F.); it is said also to render other oils mixed with it soluble in alcohol. It saponifies readily, yielding several fatty acids, the chief of which is ricinoleic peculiar to this oil, and another appears to be palmitic. Its drastic principle and optical properties still await investigation. Some of its uses have already been alluded to. For medicinal use, as a purgative, the cold drawn oil is the only kind fit for human subjects; but the oil obtained by roasting and boiling, or that extracted by alcohol, is preferred by veterinary sur geons, as containing much more of the drastic principle, and being therefore more powerful. The common kinds are largely used by leather-dressers, principally, perhaps, for morocco leather, but with equal success on all descriptions ; moreover, it repels rats and other vermin, and does not interfere with subsequent polishing. As a lubricant, it is in extensive use in Europe and America ; and as a lamp-oil, in India, Brazil, &c. Chiefly three sorts appear in the London market—that expressed here from imported (essentially Egyptian) seed, E. Indian expressed, and American expressed. The oil is imported in tins, barrels, hogsheads, and duppers. It is often adulterated with poppy-seed-oil and croton-oil. (See Drugs, p. 798).
Chaulmugra- and Lukrabo- [Lucrabau-] oils.—The valuable medicinal oils known as chauemugra in India, as lukrabo in Siam, and as ta-fung-tsze in China, are obtained from the seeds of one or more species of Gynocardia ; the Indian species is called G. odorata (Chaulmugra, Hydnocarints odorata), while the other kinds are not yet specifically determined, though some botanists consider them identical. G. odorata grows in the forests of the Malayan peninsula and E. India (Tenasserim, Rangoon, Chittagong) as far north as Assam, and thence westwards along the base of the Himi layas, and on the Khasia Hills. It is a large tree, bearing fruits somewhat resembling an orange, in the pulp of which are imbedded the seeds whence the oil is extracted. The fragrant flowers appear in April-May, and the fruits ripen in December. The latter are then collected, dried, and sent to Calcutta ; the outer integument is removed, and the kernels alone are treated for their oil, during a period extending to the end of February. The freshest seeds, gathered in December, afford the best yield of oil, which (by expression) amounts to about 10 per cent. Both cold and hot
expression are adopted, the oil obtained by the former having superior keeping qualities. At ordinary European temperatures, the oil is a granular solid, resembling beef-dripping in colour and appearance, but of firmer consistence. In the Indian climate, it is more liquid, of a pale-sherry colour, and sp. gr. ; a granular, white, fatty deposit is thrown down by keeping. The melting point as ascertained in England is 42° (1074° F.), when the sp. gr. is 0-930. It has an acid reaction a slight persistent acrid flavour, and a faint scammony-like odour. A peculiar feature of the expressed oil is its (hitherto) indestructible green colour. The kernels treated with ether afford over 50 per cent. of fatty oil, which is almost colourless, or brownish when the seeds are not fresh. The expressed oil concretes at 17° (624° F.) ; that extracted by ether or bisulphide of carbon requires a lower temperature. The chief constituents of the oil are about 63 per cent. of palmitic acid and 114 per cent. of gynocardic acid in combination with glyceryl as fats ; the latter acid is the seat of the colour and flavour, and probably also of the medicinal activity (see Drugs, p. 799) of the oil. The chaulmugra-oil met with in the Indian bazars is universally adul terated, and quite unreliable, as the detection of its impurities is practically impossible. The pure oil has been largely introduced into medical practice in this country through T. Christy and Co., Fenchurch St., and Corbyn, Stacey & Co., High Holborn. Of the closely allied Siamese drug, it may be mentioned that 48 piculs (of lb.) of lukrabo-seeds were exported from Bangkok to China in 1871. In 1879, Hankow imported 742 piculs of the seed, value 4901. ; and Shanghai imported 5521 piculs from foreign countries, and 924 from Hong Kong and Chinese ports, 4104 being retained for local consumption.
Chequito.—This name is applied by the Kaffirs to a fatty substance yielded by the fruit of the " butter-tree " (Combretum butyraceum) of S.-E. Africa. It is largely used by them in admixture with their food, and is exported. It consists of about 25 per cent. oleine and 75 margarine, and possesses an aromatic flavour.
Cherry-oil.—The " stones " of the American red cherry (Prunus serotina) have for several years past appeared in the market in such abundance and at such a price as to induce manufacturers to extract their oil. For this purpose, the whole "stones," kernels and shells together, are ground to fine powder, which is carefully dried, and subjected to hydraulic pressure of about 2000 lb. a sq. in. The yield is about 5 per cent. of an oil having a slight (but not injurious) odour of bitter almonds, sweet and agreeable flavour, and a dark-green colour which cannot be removed by either cold or hot water or alcohol ; its sp. gr. is 0-906 ; it solidifies at - 94° (15° F.) ; its boiling-point is above that of mercury, which is 350° (662° F.), when it takes fire and burns with a yellow flame, leaving a. pitch-like residue ; at 138° (280° F.), it emits vapours, which are not disagreeable till 315° (G00° F.) is reached ; it is insoluble in alcohol, but freely soluble in ether, ehlorofonn, oil of turpen tine, olive-oil, and benzol.