Ixii 



INTRODUCTION. 



perties, for, if it be sliced and exposed for some 

 hours to the direct rays of the sun, cattle may 

 eat it with perfect safety. The roots are some- 

 times eaten by the Indians, sunply roasted with- 

 out being previously submitted to the process of 

 grating and expressing the juice. They also use 

 the juice for poisoning their arrows, and w^ere 

 acquainted with the art of converting it into an 

 intoxicating liquid before they were visited by 

 Europeans. By washing the pulp in water and 

 suffering the latter to stand, a sediment of starch 

 is produced, which, under the name of tapioca, 

 is extensively imported into Europe, where it is 

 used for all the purposes to which arrow-root 

 and sago are applied. It is light, digestible, and 

 nourishing, so much so, indeed, that half a pound 

 a day is said to be sufficient to support a healthy 

 man. The meal or flour called farina is a pre- 

 paration of the same root. Caoutchouc, or India- 

 rubber, is a w^ell-known elastic gum, furnished 

 in greater or less abundance by many plants of 

 this order, but especially by a South American 

 tree SipJionia or Hevea elastica. In order to 

 obtain it, the natives puncture the trees in the 

 rainy season, upon which a thick juice of a yel- 

 lowish colour exudes, which becomes darker by 

 exposure to the air. If kept in well closed bot- 

 tles, it will retain its fluidity for a considerable 

 time ; but, if heated or exposed to the air in thin 

 films, its moisture evaporates, and it quickly as- 

 sumes the form under w^hich we are acquainted 

 with it. By the Indians of South America it 

 is applied in successive layers to models of clay, 

 and dried in the smoke of a fire, until it has 

 acquired the requisite thickness ; the clay is 



