CAOUTCHOUC AND GUTTA-PERCHA. 217 
mains unchanged. Sulphurized, or, as it is called, vuleanized caoutchouc be- 
comes neither soft nor glutinous in a tropical heat, nor bard and brittle in the 
cold of a northern winter; even a temperature of 100° and upward has no effect 
on it. Solvents, too, lose all their power of affecting it. 
But before industry could draw considerable advantage from this circum- 
stance, various experiments were required, for the discovery of the pre- 
cise relation of sulphur to caoutchouc, and of the exact temperature to which 
the mixture was to be subjected. The elucidation uf these difficult points we 
owe to the American Goodyear, through whom the caoutchouc industry has 
risen to a height never dreamed of before. 
According to the earlier way of proceeding, the sheets of caoutchoue were 
laid in fluid sulphur, of which they absorbed from ten to fifteen per cent. 
within two or three hours. This causes no alteration in the properties of the 
organic substance, while at a temperature of from 135° to 160° such an altera- 
tion is brought about in a few minutes. A longer subjection to this temperature 
is injurious; the manufactured article becomes less pliablesand elastic, and be- 
comes hard and brittle, so that it tears off short even on a slight stretching. The 
same occurs when too much sulphur is absorbed, and this is under that method 
always the case, only from one to two pounds of sulphur chemically uniting 
with the organic substance. ‘The rest remains lying between the pores, and is 
removed by mechanical means by alternate stretching and contraction, or rather 
by chemical substances acting as solvents, as alcoholic lye, ether, sulphide of 
carbon, oil of turpentine, or benzine. ‘The latter process must always be applied 
“ when the vulcanized caoutchoue is brought in connexion with metals, which 
the residue of sulphur not chemically united would affect injuriously. 
The difficulty of observing the right measure of sulphurization is proved 
by the manifold complaints about the inferiority of the manufactured articles in 
the market, which by no means possess the so much vaunted excellent qualities. 
It is easier to observe that precise limit under the methods of cold vuleaniza- 
tion recommended by Parkes and Gerard. The caoutchoue, or the article man- 
ufactured from it, is steeped in a mixture of chloride of sulphur and sulphide of 
carbon, or in sulphide of potassium. But in whatever way the sulphurization is 
effected, it does not take place uniformly over the whole of the mass. To 
judge by its reaction with solvents, there scem to be two different compounds, 
besides which there is also unaltered caoutchoue. 
Although gutta-percha adapts itself to manufacturing processes more 
easily than caoutchoue, it yet gains by sulphurization, becoming thereby more 
elastic and insensible to changes of temperature as well as to solvents. Better 
still than pure gutta-percha is a mixture of both substances. 
It can be said that sulphurization has given an endless variety to the use of 
those substances. Nothing could prove this more than a visit to the industrial 
exhibitions of London, Munich, and Paris. At the first named, extraordinary 
interest was excited by a collection of gutta-percha manufactures, prepared by 
natives of India, to the exhibitor of which (W. Kerr, of Singapore) the prize 
medal was awarded. ~ 
The chief representatives of this branch of industry are North America, 
England, and France, and the master in it is Goodyear, whom his invention 
promises to make immensely rich. Not only the manufacturers of his country 
are tributary to him, on account of his patent, but also numerous firms in 
France. For a time Goodyear was the lion of the whole Union. A country- 
man of his, however, (Mr. Day,) contested his right to the monopoly, and this 
gave rise to a gigantic lawsuit, which agitated the whole Union, the most cele- 
brated lawyers, and among them the great statesman Daniel Webster, pleading 
on the one side or the other. 
The manufacture of India-rubber goods was everywhere very limited 
before the invention of vulcanization; since 1844, however, this immensely 
