The manufacture of vulcanite resembles in principle that of ordinary rubber goods at all stages, except that a larger proportion of sulphur is added in the mixing and that vulcanisation is carried out for a longer period and at a higher temperature. As we proceed to stages of vulcanisation beyond that for ordinary hard vulcanised rubber, we pass through the tough and springy condition of the substance employed as artificial whalebone, and finally arrive at the hard and brittle state of the vulcanite or ebonite employed for making fountain pens and the mouthpieces of pipes to name only two of a large variety of uses. In making whalebone-substitute the amount of sulphur added to the rubber is from 12 to 14 per cent; for the harder ebonite from 24 to 35 per cent is required. Vulcanisation is carried out either for a prolonged period 8 to 12 hours at a comparatively low temperature about 135°C, or for a shorter time at a higher temperature.