Raw rubber, as produced on the plantations, is almost invariably subjected to the process of vulcanisation in the production of manufactured rubber articles as we know them. Previous to the advent of plantation rubber, the raw material was purchased by the manufacturer in a moist and impure condition; frequently the rubber was adulterated with sand, dirt, and even small stones. Consequently it was the invariable practice of the rubber manufacturer to wash the raw rubber and convert it into crepe, which was then hung and air-dried before use. The effect on the rubber, if of high grade, was more severe than the washing and crepeing process on the plantation, because the rubber was not a soft coagulum but generally dried on the surface and semi-hard. The power required was considerable, and the resulting crepe was consequently softer and more susceptible to heat than plantation first latex crepe. Much of the "wild" rubber was soft and tacky and inferior to "earth-scrap." Vulcanising in its simplest aspect consists in mixing the rubber with sulphur and heating the product under regulated conditions. The effect of heat on the inferior grades of "wild" rubber is very marked. A soft, sticky, and resinous material is transformed into a relatively tough and elastic product. The effect of vulcanising on the better grades is less marked, but immediately apparent. On the other hand, the effect of vulcanising is least apparent on first latex plantation grades, because in these we have a raw rubber prepared in a manner best suited to retain its natural characteristics. The need of vulcanising in the process of manufacturing rubber goods became an axiom in pre-plantation days, and it is only quite recently that attempts have been made to utilise raw rubber directly, without vulcanisation, particularly for shoe soles. For this purpose a thick dense crepe has been found satisfactory. Smoked sheet rubber is not generally suitable, apparently owing to its microphysical structure. It is possible that the process of rolling in the making of dense crepe compacts the rubber particles, yielding a harder and more resilient product. The rolling must not be carried too far, or the "working" of the rubber will approximate to a preliminary mastication, and the product will be weakened. The utilisation of crepe rubber directly has not yet been sufficiently tested to enable a definite conclusion to be reached as to its future scope, but it is obvious that for use in a raw state some modification in preparation may be advantageous. The present method--_e.g._, coagulation with acetic acid--does not yield the hardest and toughest rubber.