In Germany, the following method is sometimes used for the preservation of wood: Mix 40 parts of _chalk_, 40 parts of _resin_, 4 of _linseed oil_; melting them together in an iron pot; then add 1 part of native _oxide of copper_, and afterwards, carefully, 1 part of _sulphuric acid_. The mixture is applied while hot to the wood by means of a brush, and it soon becomes very hard.[15] Mr. Cobley, of Meerholz, Hesse, has patented the following preparation. A strong solution of _potash_, _baryta_, _lime_, _strontia_, or any of their salts, are forced into the pores of timber in a close iron vessel by a pump. After this operation, the liquid is run off from the timber, and _hydro-fluo-silicic acid_ is forced in, which, uniting with the salts in the timber, forms an insoluble compound capable of rendering the wood uninflammable. About the year 1800, Neils Nystrom, chemist, Norkopping, recommended a solution of _sea salt and copperas_, to be laid upon timber as hot as possible, to prevent rottenness or combustion. He also proposed a solution of _sulphate of iron_, _potash_, _alum_, &c., to extinguish fires. M. Louis Vernet, Buenos Ayres, proposed to preserve timber from fire by the use of the following mixture: Take 1 lb. of _arsenic_, 6 lb. of _alum_, and 10 lb. of _potash_, in 40 gallons of water, and mix with _oil_, or any suitable tarry matters, and paint the timber with the solution. We have already referred to the conflicting evidence respecting alum and water for wood: we can now state that Chapman’s experiments proved that _arsenic_ afforded no protection against dry rot. Experiments in Cornwall have proved that where arsenical ores have lain on the ground, vegetation will ensue in two or three years after removal of the ore. If, therefore, alum or arsenic have no good effect on timber with respect to the dry rot, we think the use of both of them together would certainly be objectionable. The last we intend referring to is a composition frequently used in China, for preserving wood. Many buildings in the capital are painted with it. It is called _Schoicao_, and is made with 3 parts of blood deprived of its febrine, 4 parts of lime and a little alum, and 2 parts of liquid silicate of soda. It is sometimes used in Japan. It would be practically useless to quote any further remedies, and the reader is recommended to carefully study those quoted in this chapter, and of their utility to judge for himself, bearing in mind those principles which we have referred to before commencing to describe the patent processes. A large number of patents have been taken out in England for the preservation of wood by preservative processes, but only two are now in use,--that is, to any extent,--viz. Bethell’s and Burnett’s. Messrs. Bethell and Co. now impregnate timber with _copper, zinc, corrosive sublimate, or creosote_; the four best patents. We insert here a short analysis of different _methods_ proposed for seasoning timber:--