12 COMMEECIAL BOTANY. 



conspicuous part. As an insulator, hov/ever. India-rubber 

 possesses a superiority over gutta-percha in its much higher 

 resistance and considerably lower capacity. For torpedoes 

 and military telegraphs, again, it is largely used, because it 

 is not so readily injured as gutta-percha by rough handling 

 or by heat. One of the most recent adaptations of rubber 

 is in the manufacture of kamptulicon for floor-covering.s, 

 which is composed of waste rubber and cork dust. 



Para-rubber (Hevea hrasiliensis). — In the earlier years 

 of the rubber industry the supply came almost exclusively 

 from Para. Other sources have, how3ver, since been dis- 

 covered, and at the present time the rubber supplies to this 

 country are procured from various plants of South America, 

 Africa, India, Borneo, and the Malay Archipelago. In con- 

 sequence of the very great demand for this substance, and 

 the fear lest the sources of supply should become exhausted, 

 the attention of the Kew authorities was first drawn in 1873 

 to the necessity of introducing the Para-rubber plant to 

 India In the " Report on the Progress and Condition of 

 the Royal Gardens at Kew" for that year the following 

 paragraph occurs : — " Dr. Kmg, the Superintendent of the 

 Calcutta Botanic Gardens, has returned to his duties, taking 

 with him living plants of the true India-rubber plant of 

 Para (Hevea brasiliensis), the seeds of which were procured 

 from the Amazons and sent to Kew by Mr. Markham of 

 the India Office." Again^ in the report for the following 

 year (1874), Dr. (now Sir Joseph) Hooker writes: — "The 

 plants of the true India-rubber of Para {Hevea brasiliensis), 

 which I stated in my last report had been taken out to India 

 by Dr. King, Superintendent of the Calcutta Botanic 

 Gardens, have safely arrived, and have already to some 

 extent been propagated by cuttings. The propagation of 

 this tree is extremely important, not merely from the valu- 

 able quality of the rubber obtained from it, but also in view 

 of the diminished supply from the Indian Ficus elastica, 



