288 



The Supplement to the Tropical Agriculturist 



amount of the annual crop is not given in the re- 

 turns, but it is estimated to be under 100,000 

 bushels. The imports of castor seed to the 

 United States in the fiscal year 1908-9 amounted 

 to 613,708 bushels, and of castor oil for the 

 same period to 6,846 gallons. These were de- 

 rived chiefly from India, but seed was also im- 

 ported from Brazil. 



Although nrt native to Brazil the castor plant 

 finds in that country a suitable soil and climate, 

 and has become naturalised to a large exteut. 

 The consumption of castor oil in Brazil is large, 

 and there are a number of castor-oil factories 

 mainly in the State of Pernambuco. 



It will be seen from the foregoing informa- 

 tion that, whilst there is a very large de- 

 mand for castor seed and castor oil, this de- 

 mand is met from comparatively few sources, 

 and that many of the importing countries 

 are in a position, as regards climate, to 

 produce all the castor seed they require. This 

 aspect of the question has been seriously con- 

 sidered in recent years, in Australia and certain 

 of the South African States, but, so far as is 

 known at present, but little has been done to 

 establish an industry in either of these countries. 

 The manufacture of cat tor oil in the United 

 Kingdom has been established comparatively 

 recently, and this has given a further incentive 

 to the production of castor seed in various Bri- 

 tish tropical and subtropical colonies. For these 

 reasons a large number of inquiries had been 

 received at the Imperial Institute in recent 

 years, on the one hand from manufacturers de- 

 siring new sources of supply of castor 3eed, and 

 on the other from planters in the colonies de- 

 sirous of undertaking the production of this seed. 

 Pkefaration of Castor Oil. 



Large quantities of castor oil are prepared in 

 India by crude native methods of express-ion as 

 well jas by modern machinery. In the United 

 Kingdom the greater part of the castor seed im- 

 ported is crushed at Hull, and in France at 

 Marseilles, the methods of obtaining the oil being 

 similar to those employed for other oil seeds. 



For the finer grades of castor oil, such as that 

 required for medicinal use, selected seed istaken, 

 the husk, which is devoid of oil and comprises 

 about 20 per cent of the weight of the seed, is 

 removed, and the soft kernels are expressed in 

 the cold ; by this means an almost colourless oil 

 is obtained, which is free from the poisonous 

 principle, ricin, present in the seeds. Thib is 

 termed " cold drawn" oil. The remaining cake 

 is then broken up and pressed a second, or 

 even a third time, when it yields an inferior oil 

 of yellowish or brownish colour unfit for medic- 

 inal use. The last traces of oil can be ex- 

 tracted by solvents, carbon disulphide or alcohol 

 being used instead of light petroleum on ac- 

 count of the insolubility of castor oil in light 

 petroleum. 



Inferior seed is hot pressed directly or is ex- 

 tracted by solvents alone. After expression the 

 oil is refined by steaming, which causes coagu- 

 lation of albuminous matter and renders inert 

 the fat-splitting onzyme which, if left in the oil, 

 would cause it to rapidly turn rancid. 



Castor seed of commerce contains from 46 to 

 53 per cent of oil, and Lewkowitsch states that 



on a manufacturing scale about 40 per cent is 

 obtained by expression, the first pressing yield- 

 ing about 33 per cnt. 



Uses of Castor Oil. 



The pure "cold drawn" oil is largely era- 

 ployed in medicine as a purgative, its action 

 being due to the ricinoleic acid. Numer- 

 ous dry preparations are now made in which 

 the taste of the oil is marked by various means. 

 In one method (German Patent 150,554) the oil 

 is mixed with milk sugar; whilst another pre- 

 paration is manufactured by emulsifying the 

 oil with gum arabic and treating with magnesia 

 and lecithin. 



Castor oil is largely employed as a lubricant 

 in India, but is rather too viscous to be used in 

 this way in cold climates, although it is used 

 for marine engines and for internal combustion 

 (petroi) engines. It is employed for dressing 

 leather belting and for "fat liquoring" in the 

 leather industry. 



An important application is in the manufac- 

 ture of "turkey red" oil, largely used in 

 alizarin dyeing. This is prepared by treating 

 the oil with concentrated sulphuric acid at a 

 temperature below 35 deg. C. This "sulphon- 

 ated " oil is washed, and ammonia or soda 

 added until a sample of the liquid gives a clear 

 solution in water. The use of turkey-red oil 

 improves the lustre of the dye, but the reason 

 for this action is not clearly understood. 



Castor oil is insoluble in light petroleum or 

 hydrocarbon (mineral) oils, but by heating to 

 about 300 deg. C. for several hours, either at 

 atmospheric pressure or under increased pres- 

 sure, the oil polymerises and becomes soluble in 

 hydrocarbon oils, and can then be used for 

 making compound lubricating oils. 



Castor oil is also employed in the manufacture 

 of so-called ' rubber substitutes.' These are 

 prepared by treating the oil with sulphur at an 

 elevated temperature, or by treating a solution 

 ofthe oil with sulphur chloride at ordinary tem- 

 peratures. The ' soda soap ' of castor oil re- 

 requires large quantites of brine for soapmaking 

 to any extent ; it has, however, the property of 

 imparting transparency to soaps, and is con- 

 sequently employed in the manufacture of trans- 

 parent soaps. 



A less important use of castor oil is the pro- 

 duction of 'cognac' oil. For this purpose castor 

 oil is submitted to dry distillation, when a mix- 

 ture of cenanthaldehyde and undecylenic acid, 

 constituting the ' cognac oil,' pass over, a bulky 

 rubber-bke mass remaining in the retort. 



Castor cake or meal is largely employed as a 

 manure, the large quantities produced in Mar- 

 seilles being employed by growers of oarly 

 vegetables. 



In India the residue from the native method 

 of preparing the oil, castor ' pomace ' contains a 

 higher percentage of oil than that produced by 

 expression in hydraulic machinery or by extrac- 

 tion with solvents, and is employed largely in 

 India for manuring, and to a smaller extent for 

 stuffing the soles of native made shoos, for caulk- 

 ing timber, as fuel, and for makingillumiuating 

 gas. — The Journal of the Jamaica Agricultural 

 Society. — July, 1911. 



