776 



GUTTA-PERCHA 



no interest for the manufacturer, and we refer the chemical student to M. Pay en's 

 Memoir. 



The juice of Mxiddar has been proposed as a substitute for gutta-percha, but wo are 

 not aware that it has in any manufacture taken its place. Dr. Falconer describes a 

 new kind of gutta-percha, which grows in the most southern British possession of the 

 Merguin Islands, Indian Ocean. 



If a solution of gutta-percha in chloroform bo mixed with 3 parts of ether, and ex- 

 posed for some time to a temperature below 15, the gutta-percha is precipitated as a 

 white powder, forming when washed and dried a soft white mass. On spreading this 

 solution on a plate of glass, a skin is formed, resembling kid-glovo leather, which 

 becomes transparent on the application of heat. These films are beautifully white, if 

 carefully prepared, and they have been employed in the manufacture of the finest 

 kinds of artificial flowers. 



In 1848, Dr. Faraday drew the attention of experimentalists to the highly insulating 

 power of gutta-percha, which not only possesses this property under ordinary cir- 

 cumstances, but likewise retains it under atmospheric conditions which would make 

 the surface of glass a good conductor. This has led to its almost universal adoption 

 as the insulator for the wires of the electrical telegraph. When buried in the earth, 

 unless it is attacked by insects, or by a fungus, it retains its highly insulatory power, 

 and we have every reason for believing that gutta-percha does not undergo a change 

 when immersed in sea-water. It has, however, been found, that when it has been 

 exposed to the intense sunshine of India, it undergoes a remarkable change ; oxygen 

 is absorbed, the gutta-percha loses its coherence, and at the same time its powers of 

 insulation. 



Some idea of the progress made in the applications of gutta-percha will be found 

 by the following Table of Imports. The demand for this substance is still increasing, 

 and it is to be feared that a destructive process is adopted in collecting the juice from 

 the trees to meet the demand : 



1850 

 1851 

 1852 

 1853 

 1854 

 1855 

 1856 

 1857 



The gutta-percha imported in 1871 and 1872 was from the following countries: 



AVAL It. 0!U TT JillCiJUll AAMUU *-" "J " ' * 



senting the colony of British Guiana, at the International Exhibition of 1862. Among 

 the varied contributions from the colony was a specimen of the dried milk of the bulk- 

 tree ; it weighed perhaps half a pound. Amongst the numerous individuals VIM 

 visited the Guiana department was Mr. Charles Hancock, who is well known in the 

 gutta-percha trade. This gentleman was struck with the appearance of the specimen, 



