THE INDIA-RUBBER INDUSTRIES. 805 



of short chimney is fixed over the fire to lead the smoke compactly 

 upward. As soon as the first layer of juice has become indurated, 

 the bat is again dipped, and the drying operation is repeated, layer 

 after layer being thus dried on the bat, until a thickness of nearly an 

 inch is attained. A knife-cut is now made in the bottle or biscuit of 

 caoutchouc thus obtained, so that it can be removed from the wooden 

 bat, and exposed to the air to become still further indurated. Para 

 caoutchouc, prepared in this manner, has a fragrant, aromatic odor, 

 which you can study for yourselves in the samples now before you. 



The residues of juice left in the various vessels employed, the scrap- 

 ings of the incisions, together with other materials, which the ingen- 

 ious native thinks he can shuffle off on the unsuspecting merchant 

 as caoutchouc, are made into balls, and sold as " negro-head." The 

 negro-head rubber is frequently made into crude representations of 

 animals, and there are several such works of native art On the table 

 as, for example, this specimen, which will pass about equally well for 

 a horse, a pig, or a crocodile. 



Here is a piece of Para bottle-rubber, which has been boiled for 

 some hours in water, and you see that it is now so far softened as to 

 render it easy to pull asunder the several layers of which it is com- 

 posed, its laminated structure being thus very well illustrated. 



The milky juice of the Para rubber trees, of which you see a speci- 

 men before you, has approximately the following composition : 



Caoutchouc 32 



Albuminous, extractive, and saline matters 12 



Water 56 



Total 100 



As a rubber-producing tree, the Flcus elastica stands next in im- 

 portance of the heveas. The Ficus elastica grows abundantly in India 

 and the East Indian Islands, one district in Assam, thirty miles long 

 by eight miles wide, being said to contain 43,000 trees, many of them 

 attaining a height of a hundred feet. This tree also grows freely in 

 Madagascar, and it is well known to us as a greenhouse plant. Fig. 

 3 represents a Ficus elastica now growing out of doors in the Pare 

 Monceau at Paris. 



The juice of the Ficus elastica contains notably less caoutchouc 

 than that of the American trees, the proportion very often falling as 

 low as ten per cent, of the juice. 



A vine-like plant, the Urceola elastica, which grows abundantly in 

 Madagascar, Borneo, Singapore, Sumatra, Penang, and other places, 

 yields a considerable amount of caoutchouc of very good quality. Af- 

 rica yields a considerable quantity of caoutchouc, but generally soft 

 and of inferior quality. It is believed to be yielded by various species 

 of landolphia, ficus, and toxicophlea. Here are some specimens of 

 African rubber this specimen, representing the quality known as 



