PREPARATION OF INDIA-RUBBER. 
207 
ehout is not affected by any known solvents, as bisulphuret 
of carbon, naptha, or turpentine ; 3d, it is not affected by 
heat short of the vulcanizing point ; 4th, it acquires extra- 
ordinary powers of resisting compression. Thus, a can- 
non-ball was broken to pieces by being driven through a 
a mass of vulcanized caoutchouc — the caoutchouc itself 
exhibiting no other trace of its passage than a scarcely per- 
ceptible rent. The applications of this substance appear to 
be almost infinite. Our readers are familiar with the use- 
fulness of the u elastic bands;" but they may not be aware 
that the same fabric, adjusted in size and strength to the 
purpose required, furnishes springs for locks and for the 
racks of window-blinds. It is also capable of being mould- 
ed into the most intricate ornaments ; its characertistic elas- 
ticity removing all embarrassments in relieving the undercut 
parts. It furnishes impervious bottles' for volatile sub- 
stances, like sether ; as well as an excellent ink-stand. It 
is adapted to protect from corrosion, wires subjected to the 
action of the sea, as is the case of the wires required for the 
projected electric communication between England and 
France. For the same reason, air-tubes of vulcanized rub- 
ber are better suited for life-boats than those formerly made 
of canvass, which are liable to be destroyed by the action 
of the water. A similar tube has been used with success 
as a substitute for an iron band as the tire of a carriage- 
wheel; and it is stated that a vehicle so arranged runs 
much easier than on the present plan. But perhaps the 
most important application is in its use in railroads and 
railroad carriages. In the former, it is laid between the 
rail and the sleeper, and thus prevents the rails from indica- 
ting any traces of the pressure ; and the springs connected 
with the buffers of the latter, when formed of vulcanized 
caoutchouc, can neither be broken, nor can their elasticity 
be surmounted by any degree of concussive violence. In 
conclusion, Mr. Brockedon exhibited objects illustrative of 
