Colonel Scott, Chief Engineer at Bombay, records instances of timber being boiled under pressure in various antiseptic solutions, such as sulphate of copper, arsenious acid, and corrosive sublimate, with satisfactory results; but considerable apparatus is necessary, and the expense forbids its use except in large public works. On the other hand, in 1847, Mr. G. Jackson, being engaged under Mr. Rendel, C.E., on works in India, tried several experiments with Mr. J. Bourne, in order to test the possibility of preserving timber from the ravages of the white ant. Ninety pieces of wood, 9 inches long by 4 inches square, saturated according to the different processes of Burnet, Payne, and Margary,[31] under the direction of the patentees themselves, were experimented upon, in five situations, one with a considerable amount of moisture, and four dry; through inadvertency Mr. Bethell’s specimens were only tested in the dry positions. The result was, that where there was moisture the timber was entirely destroyed, whilst where they were kept dry the result was better, but still not satisfactory. It seems difficult to account for these different results obtained by Colonel Scott and Mr. Jackson; but evidently the same strength of solutions, and the same qualities and descriptions of woods, cannot have been used by each gentleman. Captain Mann and Captain McPherson painted the joists and planking of several buildings at Singapore with _gambir composition_, and the result was perfect success, although the buildings had been previously infested with white ants. Gutta gambir is juice extracted from the leaves of a plant of the same name (_Uncaria gambir_) growing in Sumatra, &c., inspissated by decoction, strained, suffered to cool and harden, and then cut into cakes of different sizes, or formed into balls. Chief places of manufacture, Siak, Malacca, and Bittany; gambir is now imported to England to a slight extent. The gambir composition referred to is made as follows: Dissolve three pints of gambir in twelve pints of dammer-oil over a slow fire; then stir one part of lime, sprinkling it over the top to prevent its coagulating and settling in a mass at the bottom; it must be well and quickly stirred. It should then be taken out of the cauldron, and ground down like paint on a muller till it is smooth, and afterwards returned to the pot and heated. A little oil should be added to make it tractable, and the composition can then be laid over the material. To be treated with a common brush. Against the _Teredo navalis_ may be substituted the same proportion of black varnish or tar for dammer-oil, of course omitting the grinding down, which would not answer with tar. Burnett’s chloride of zinc process is said to be a good preservative for wood liable to be attacked by ants: the zinc penetrates to the heart of the wood.