283 SELECT PLANTS FOR INDTJSTllIAL' CULTURE 



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 filtration it is purified. 

 For obtaining oil to be used for lubrication of machinery or 

 other technological 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 ex- 

 posure 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 indus- 

 trial 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 crystalline isoeetic acid (a glycerid) . The oil contains 

 also a non-crystalline 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. 



Eobiuia pseudacacia, Linn^. 



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 

 aliment as Pinus silvestris and nearly as much as poplars. It 



