Scotch Fir Roofs.
Scotch fir roofs are occasionally made. The method of giving durability to the timber for this purpose consists in first cutting the wood to the required size, and then steeping it for a fortnight in a pond of lime-water; it is found that the acid contained in the wood becomes crystallized by combining with the alkali of the lime. Sir Charles Menteath is said to have some farm buildings which, although roofed with Scotch fir forty years ago, are as well protected now as when the roofs were first laid on; the wood having been previously steeped in lime-water. The sulphate of copper, the chloride of zinc, the corrosive sublimate, and the various other chemical substances which have been recommended of late years as means for preventing the decay of timber, will possibly render the use of timber roofs more practicable than it has been hitherto considered.