The prolonged storage of lower grade rubbers is attended by more risk, especially in the case of the lowest grade (earth-scrap) from estates which neglect the practice of regular and frequent collection of the raw product. The same reservation applies to crepes made from tree-scrap which is not collected daily. In these types of crepe rubber "tackiness" may be initially present only in small degree, but the final damage may be immensely greater by close contact of the folded rubber during prolonged storage. When we come to discuss the possibility of storage of smoked sheets, the difficulties become immensely greater. We have yet no reliable experience as to the keeping properties of this grade when properly prepared, fully cured, correctly packed, and stored under the best of local conditions. It is understood, of course, that in the qualification by the term "local" conditions, we assume it to be more difficult to store rubber generally in Malaya than in a temperate climate. The average temperature and humidity of the atmosphere are here much more favourable to the development of mould growths than would be the case, say, in Great Britain. In discussing this question, as far as it refers to the preservation by storing of smoked sheet rubber, it is not fair to draw conclusions as to the likely behaviour of packed rubber from data based upon observation of loose specimens. We have samples of smoked sheets prepared in 1910, and these, superficially, appear to have remained unchanged. No mould is present and, as far as intermittent observation enables us to judge, moulds have never been incident. Whether such rubber would have been preserved in this condition had it formed part of a packed case, is a point upon which we have no experience; neither can we give any opinion. It seems true, however, that loose specimens "keep" better than bulk samples of the same preparation. It cannot be argued that the present good condition of these old specimens may be due to correct preparation. In those days methods and formulæ were rather haphazard, especially in view of the fact that the daily variability of dry rubber content of latices was not then recognised. One would rather submit the factor of adequate smoke-curing as the chief influence in the superficial preservation of smoked sheets. Ten or eleven years ago it was considered advisable to allow the rubber to remain in the smoke-house for a period extending well beyond that necessary for ordinary drying. As a result, very dark rubber was produced, which was thoroughly impregnated with the products of wood combustion. There would seem to be little doubt that this procedure was responsible for the prolonged freedom from mould growths.