CAOUTCHOUCINE 



713 



420 



Our Exports of caoutchouc manufactures in the same year were valued at 

 854,539?. 



In 1872 we imported 157,148 cwls., valued at 1,762,886J. 



CAOUTCHOUCINE. A thin volatile oily liquid, obtained by the destructive 

 distillation of caoutchouc. Mr. C. Greville Williams has shown that this liquid is 

 composed principally of two hydrocarbons, called caoutchin C 20 H 16 (C !0 H 1S ), and isoprene 

 C 10 H 8 (C 5 H 8 ). 



Mr. William Barnard, in the course of some experiments upon the impregnation 

 of ropes with caoutchouc, which he conducted at the 'factory of Messrs. Enderby at 

 Greenwich, discovered that when this substance was exposed to a heat of about 600 F. 

 it resolved itself into a vapour, which, by proper refrigeratory methods, was condensable 

 into a liquid possessing very remarkable properties, to which the name caoutchoucine 

 has been given. For this invention ' of a solvent not hitherto used in the arts,' Mr. 

 . Barnard obtained a patent, in August 1833. His process for preparing it is described 

 in his specification as follows : ' I take a mass of the said caoutchouc, or India- 

 rubber, as imported, and having cut it into small lumps, containing about two cubic 

 inches each (which I prefer), I throw these lumps into a cast-iron still (which I find 

 adapted for the purpose, and a diagram of which is annexed to, and forms part of 

 this my specification), with a worm attached (fig. 420) : A is the still ; B, the cover 

 ground to a metallic fit, to admit of a thermometer to take the temperature ; c, the 

 fire-place ; D, the ash-pit ; E, the worm-tub and worm ; F, the brickwork of the still ; 

 o, a roller and carriage, in connection with a crane, or other means, to raise the cover 

 to take out the residue, and to charge the same ; H, the chain. 



' I then apply heat to the still in the usual manner, which heat is increased until the 

 thermometer ranges at about 600 F., or thereabouts. And as the thermometer ranges 

 upwards to 600 F. a dark 

 coloured oil or liquid is distilled 

 over, which I claim as my said 

 invention, such liquid being a 

 solvent of caoutchouc, and other 

 resinous and oleaginous sub- 

 stances. When the thermo- 

 meter reaches 600 F;, or there- 

 abouts, nothing is left in the 

 still but dirt and charcoal. 



' I have found the operation 

 of distillation to be facilitated 

 by the addition of a portion of 

 this oil, either previous or sub- 

 sequent to the rectification, as 

 hereinafter mentioned, in the 

 proportion of one-third of oil to 

 two-thirds of caoutchouc. 



' I afterwards subject the 

 dark coloured liquid thus dis- 

 tilled, to the ordinary process of 

 rectification, and thereby obtain 

 fluids varying in specificgravity, 

 of which the lightest hitherto 



has not been under 670, taking distilled water at 1,000, which fluids I also claim as 

 my said invention. 



' At each rectification the colour of the liquid becomes more bright and transparent, 

 until at the specific gravity of 0'680, or thereabouts, it is colourless and highly volatile. 



' In the process of rectification (for the purpose of obtaining a larger product of the 

 oil colourless) I put about one-third of water into the still. In each and every state 

 the liquid is a solvent of caoutchouc, and several resinous and oleaginous substances, 

 and also of other substances (such as copal), in combination with very strong alcohol. 



' Having experienced much difficulty in removing the dirt which adheres to the 

 bottom of the still, I throw into the still lead and tin in a state of alloy (commonly 

 called solder), to the depth of about half an inch, and, as this becomes fused, the dirt 

 which lies on the surface of it is more easily removed. 



' Objections have been made to the smell of this liquid : I have found such smell 

 removed by mixing and shaking up the liquid with nitro-muriatic acid, or chlorine, 

 fa the proportion of a quarter of a pint of the acid (of the usual commercial strength) 

 to a gallon of the liquid.' 



The discovery of the chemical solvent, which forms the subject of the patent above 

 described, has excited considerable interest in the philosophical world, not only i'rom 



