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CAOUTCHOUC 



VI. SOLAIUSATIOX OF CAOUTCHOUC. 



Singular as caoutchouc is in its properties and its applications, it is probable that 

 besides the mechanical and electrical qualities and general resistance to chemical 

 action, it may yet be found to have other modifications peculiar and valuable. The 

 practical men most conversant with this substance, and deeply involved with patents 

 and successful manufactures, record their conviction of the influence of solar light, 

 and the marked distinctions supposed to exist between the influence of solar and 

 terrestrial heat upon this substance. 



Mr. Hancock says, 'In my early progress, I found that some of the rubber I 

 employed was very quickly decomposed when exposed to the sun : as the heat was 

 never more than 90, and rubber exposed to a much higher temperature was not 

 injured by it, I suspected that light had some effect in producing this mischief. To 

 ascertain this, I cut two square pieces from a piece of white rubber, one of these I 

 coloured black, and exposed it to the sun's rays ; in a short time, the piece which had 

 been left white, wasted away, and the sharp angles disappeared, it seemed like the 

 shape of a thin piece of soap after use ; the blackened piece was not at all altered or 

 affected. The lesson taught me by this experiment was of great value ever after.' 



Speaking pf the annoyances and failures in the early Macintosh goods by heat, 

 grease, &c., Mr. Hancock says, ' The injurious effect of the sun's rays upon thin films 

 of rubber we discovered and provided against before much damage accrued.' 



Mr. Goodyear says, ' In anticipation of the future as relates to a mode of treatment 

 in manufacture, which, though lightly esteemed and little thought of now, I believe 

 will be extensively practised hereafter, I feel bound to make a strong though qualified 

 claim to the process of Solarisation. This process consists in exposing caoutchouc 

 when combined with sulphur, to the sun's rays.' Again, ' when exposed to the sun's 

 rays for several hours, a change is produced which may be called natural vulcanisation, 

 in all thin fabrics or thin sheets of caoutchouc.' ' Solarisation is an effectual and 

 cheap process of curing India-rubber.' He further says, ' it is well established that 

 India-rubber melted at about 200, and in the sun's rays at 100 or less. Another 

 effect yet more remarkable in the treatment of gum elastic, is that of the sun's rays 

 upon it ; when combined with sulphur and exposed to the sun, either in hot weather 

 or cold, it becomes solarised, or divested of its adhesive quality ; whereas, no other 

 kind of light or heat has any similar effect, until the high degree of heat is applied to it, 

 about 270, which is used in vulcanising,' Goodyear, p. 114, vol. i. New Haven, U.S. 



Our recent Imports of Caoutchouc have been as follow : 



