Where field coagulating stations have been instituted on estates, it is strictly necessary that instruments should be provided in all cases; and it should be a rule that these are tested and corrected weekly by a standard instrument employed for that purpose only. This need was well recognised by many estates when, during the War and the consequent shortage of supply of "Metrolacs," a demand arose which was met in some degree by crude instruments of local manufacture, such as that commonly known as the "Castlefield bobber," contrived and made by the enterprising manager of the estate of that name. The demand for the more accurate instruments can now be met. METHODS OF USING THE INSTRUMENTS.--The "Metrolac" was devised and introduced by the writers on behalf of the Rubber Growers' Association, and directions for its use were given. Tables were prepared by means of which simple calculations for the dilution of any given latex could be made. These did not find an extended application, inasmuch as in the majority of cases native workers only were in charge of the processes of rubber preparation. In point of fact, such calculations are not strictly necessary, as the operation of standardising the latex can be done quite simply and skilfully by a trained native. Latex as it reaches the store in average weather from any particular division or field does not vary greatly in density. The trained coolie or foreman, basing his practice on experience, adds to the latex a quantity of water, and then makes a first test with the standardising instrument. Several additions of water (with thorough stirring) may have to be made before a test indicates that the correct density has been obtained, but it is surprising how quickly a skilled worker will arrive at the desired standard. Extreme or absolute accuracy is not insisted upon or desired, as avoidable delay is to be deprecated, and the result in any case is sufficiently exact for practical purposes. SKIMMING.--During the gravitation of the latex from the reception vessels (in which the standardising of the latex is effected) to the coagulating tanks, much surface froth is usually caused. This is best removed by means of a thin board of a width slightly less than the breadth of the tank. The skimmings are sometimes placed in pans and subsequently made into a second grade of sheet rubber, or they receive treatment with a small proportion of sodium bisulphite and eventually appear as fine pale crepe. The practice varies usually according to the form in which the general No. 1 grade is prepared.