THE INDIA-RUBBER INDUSTRIES. 803 



Soon after La Condamine's communication to the Academy of 

 Sciences, samples of India-rubber frequently reached Europe, and 

 scientific men began to make investigations regarding this remarkable 

 body. Between 1760 and 1770 we find Fresneau and Macquer study- 

 ing the subject, and the last-named investigator made tubes and other 

 articles of caoutchouc by dissolving it in ether and coating molds with 

 the solution, so that a solid skin of caoutchouc should remain adherent 

 to the mold on the evaporation of the solvent. 



From this time until the end of the eighteenth century, the India- 

 rubber industry may be considered to have been undergoing its period 

 of gestation, and to have been born with the dawn of the present cen- 

 tury. Among the fh*st of the important patents regarding the utiliza- 

 tion of caoutchouc is that granted in 1823 to Charles Macintosh, for 

 dissolving the substance in coal-oil, or coal-naphtha, and the use of 

 this solution as a water-proofing agent. I have here a specimen of 

 such a solution, as now manufactured by Messrs. Charles Macintosh 

 and Co., of Manchester, together with some examples illustrating its 

 uses. 



About the same time, elastic webbing was first made with threads 

 cut from the raw rubber, and other minor applications of caoutchouc 

 to the industrial arts were adopted from time to time, until the great 

 discovery of vulcanization inaugurated a new epoch in this branch of 

 industry, rendering it possible to so far alter caoutchouc as to make 

 it capable of resisting, to a great extent, the action of heat on the one 

 hand and cold on the other hand. 



The milky sap of many plants contains caoutchouc, suspended in 

 the form of minute transparent globules, these being frequently as 

 small as 30*00 to -gmrro f an mcu m diameter ; but comparatively few 

 plants contain sufficient caoutchouc to render them important sources 

 of this body. 



The trees which yield the largest supply of the best quality of 

 caoutchouc consist of various species of hevea, which flourish in the 

 northern districts of South America, especially in the province of Para, 

 some portions of the valley of the Amazon being crowded to an ex- 

 traordinary extent with heveas. The abundance of the India-rubber 

 trees in Para may be judged of by the fact that this province alone ex- 

 ported 7,340 tons of caoutchouc in the year 1877, more than half of 

 this being sent to Liverpool. 



Among the heveas most productive of caoutchouc may be men- 

 tioned the Hevea Brasiliensis, which flourishes in Para, and yields 

 some of the finest caoutchouc, and often attains a height of sixty to 

 seventy feet, with a diameter of nearly three feet ; the Hevea Guia- 

 nensis, a similarly magnificent tree, likewise abundantly productive of 

 caoutchouc ; and the Hevea spruceana, a smaller tree, which grows 

 almost exclusively in the province of Para. Fig. 1 represents the flow- 

 ers and foliage of Hevea Guianensis. 



