Vulcanized india rubber which by high proportion of sulphur and proper
vulcanization has been made hard. It is sometimes distinguished from
ebonite as being comparatively light in color, often a dull red, while
ebonite is black. For its electrical properties see Ebonite.

Both substances have their defects, in producing surface leakage.
Washing with weak ammonia, or with dilute soda solution, followed by
distilled water, is recommended for the surface, if there is any trouble
with surface leakage. It may also be rubbed over with melted paraffine
wax.