(3) No rubber should be hung in a drying-room in such a position adjacent to a window or door that it is possible for sunshine to reach it, even should coolies neglect to obey rules. (4) Instruments or vessels of copper or brass should not be used where acids are employed. LACK OF UNIFORMITY IN COLOUR.--The complaint is far less real than it was a few years ago. The introduction by the Rubber Growers' Association of the "Metrolac" led to uniform dilution of latices varying in rubber content. Previously the only known method of obtaining uniformity in colour and appearance was that by which latices from all fields were mixed together in bulk. Even so the uniformity applied only to the one bulking operation, and any other day's results might show considerable variation from the first standard. This does not take into account any observed differences in shade of colour attributable to natural oxidation which might vary in intensity from day to day. The introduction of sodium bisulphite as an anti-oxidant exerted a great influence upon the colour of pale crepes generally; but considerable variation would still have been notable but for the adoption of the scheme for uniform dilution, in addition to the use of small quantities of anti-oxidant. On most estates it is now possible, with slight exceptions due to abnormal conditions, so to treat the latex that the pale crepes prepared on any one day differ in no perceptible degree from the product of any other day. Where this is not the case it must be suspected that there has been some carelessness in manipulating the latex or the chemicals. Attention has been drawn to the fact that there may be exceptional cases, when the determining factors lie beyond the control of factory processes--_e.g._, heavy rains causing over-dilution of latex, the yielding of "yellow" latex from newly opened areas, etc. But on the whole there is now no reason why the general average product from any estate should not be uniform in colour and appearance. Furthermore, it should be possible for large groups of estates, by the adoption of uniform methods, to produce similar rubber from all the plantations. Moreover, apart from some differences caused by factors which still need determination, the total product in a general sense should not only be uniform in appearance but uniform in physical and chemical properties. BLOCK RUBBER.--This mode of preparation is employed only in comparatively few instances. The block is prepared from crepe rubber, which has been dried either in a hot-air drier or in a vacuum chamber.