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.
Creosoted timber, it is well known, resists the attacks of the white ants; but the close grain of the generality of tropical timber renders any attempt to creosote it all but useless. Of course, creosoted fir timber could be, in fact is, exported from England, but the cost of freight and other charges will always make it very expensive, and be a great drawback to its general use abroad. Mr. J. C. Mellis, Engineer to the Government of St. Helena, writes in very high terms of creosoted timber as used there, where the white ant abounds. Between the years 1863 and 1866, experiments[32] were made with many specimens of woods (by order of the Lieutenant-Governor), in order to find out those which would resist the white ant. Teak remained uninjured; jarrah wood was partially destroyed; while pitch-pine, oak, cedar, ash, elm, birch, beech, and mahogany, were quite destroyed.
In Ceylon creosoted timber is not attacked by white ants, but the black coating, if exposed, renders it so heat-absorbing, that it is apt to split, and, unless thoroughly impregnated with the creosote, a road is opened to the inside, and the ants will soon destroy all that part which is unprotected.
Coal-tar will destroy white ants. Some years ago Mr. Shields took short baulks of timber where the ants had commenced operations, and tried the system of pouring a very small stream of coal-tar through the heart of the timber which the ants had hollowed out, and afterwards splitting it open to see the result. He found the white ants completely destroyed; they were shrivelled up like shreds of half-burnt paper by the mere effluvium of the coal-tar.
Creosoting is excellent for railway sleepers, piles, &c., but it will not do for buildings, which the white ants prefer. It is objectionable for dwellings; 1st, on account of its smell, which is disagreeable; 2nd, on account of its colour, black, which is unsightly; 3rd, on account of its inflammability.
With regard to the depredations of white ants, anything of a bitter taste injected into the fibre of the wood prevents their attacks, though it may not be so good as coal-tar; even a small quantity of turpentine has the effect of killing them instantly. Carbolic acid has been used, but its smell is objectionable. In South America, the leaves of the black walnut are soaked in water for some hours, then boiled; and when the liquid has cooled, it is applied to the skins of horses and other animals, to prevent their being bitten or “worried” by insects. We do not know if this has been used as a wash, or injected into wood, to prevent it being “worried” by ants.