290 SELECT PLANTS FOR INDUSTRIAL CULTURE 



any soil, and can thus be raised even on arid places, without being 

 scorched by hot winds. It may thus become an important plant 

 also for culture in desert-tracts, and is evidently destined to be one 

 of the most eligible oil-plants for technical uses, particularly for 

 lubricating machinery, irrespective of the value of its oil for medi- 

 cinal purposes. The seeds contain about 50 per cent. oil. To 

 obtain the best medicinal oil, hydraulic pressure should be employed, 

 and the seeds not be subjected to heat ; the seed-coat should also be 

 removed prior to the extracting process being proceeded with. A 

 screw-press suffices however for ordinary supply to obtain the oil. 

 By decantation and some process of nitration it is purified. For 

 obtaining oil to be used for lubrication of machinery or other tech- 

 nological purposes, the seeds may be pressed and prepared by 

 various methods under application of heat and access of water. 

 Castor oil is usually bleached simply by exposure to solar light, but 

 this procedure lessens to some extent the laxative properties of the 

 oil. It dissolves completely in waterless alcohol and in ether, and 

 will become dissolved also in spirit of high strength, to the extent 

 of three-fifths of the weight of the latter. Solutions of this kind 

 may become valuable for various technical purposes, and afford 

 some tests for the pureness of the oil. If pressed under heat it 

 will deposit margaritin. Heated in a retort about one-third of the 

 oil will distil over, and a substance resembling india-rubber remains, 

 which saponises with alkalies. Other educts are at the same time 

 obtained, which will likely become of industrial value. These facts 

 are briefly mentioned here merely to explain that the value of this 

 easily -produced oil is far more varied than is generally supposed, 

 and this remark applies with equal force to many other chemical 

 compounds from vegetable sources, briefly alluded to in this present 

 enumerative treatise. The seeds contain also a peculiar alkaloid 

 ricinin. The solid chemical compound of castor oil is the crystal- 

 line isocetic acid (a glycerid). The oil contains also a non-crystal- 

 line acid peculiar to it (ricinoleic acid). For the production of a 

 particular kind of silk the Recinus plant is also important, inasmuch 

 as the hardy Bombyx Arrindi requires for food the leaves of this bush. 

 Even a few of the seeds if swallowed will produce poisonous effects. 



Hobinia pseudacacia, Linne. 



The North American Locust Acacia. Height to 90 feet. The 

 strong, hard, and durable wood is for a variety of purposes in use, 

 and particularly eligible for treenails, axletrees, and turnery. The 

 natives use the wood for their bows. Tree of rapid growth, and 

 attains an age of several hundred years. It may be planted closely 

 for timber-belts and hedge-shelter on farm lands. It is one of the 

 best trees for renovating exhausted land and for improving poor 

 soil. Recommended by Wessely as one of the easiest grown of all 

 trees on bare sand, though standing in need of twice as much mineral 



