At the suggestion of MM. Le Châtelier (Engineer-in-chief of mines) and Flachat, C.E.’s, M. Ranee, a few years since, injected in a Légé and Fleury cylinder certain pieces of white fir, red fir, and pitch pine with _chloride of sodium_, which had been deprived of the manganesian salts it contained, to destroy its deliquescent property. Some pieces were injected four times, but the greatest amount of solution injected into pitch pine heart-wood was from 3 to 4 per cent., and very little more was injected into the white and red fir heart-wood. It was also noticed that sapwood, after being injected four times, only gained 8 per cent. in weight in the last three operations. The experiments made to test the relative incombustibility of the injected wood showed that the process was a complete failure; the prepared wood burning as quickly as the unprepared wood. M. Paschal le Gros, of Paris, has patented his system for preserving all kinds of wood, by means of a _double salt of manganese_ and of _zinc_, used either alone or with an admixture of _creosote_. The solution, obtained in either of the two ways, is poured into a trough, and the immersion of the logs or pieces of wood is effected by placing them vertically in the trough in such a manner that they are steeped in the liquid to about three-quarters of their length. The wood is thus subjected to the action of the solution during a length of time varying from twelve to forty-eight hours. The solution rises in the fibres of the wood, and impregnates them by the capillary force alone, without requiring any mechanical action. The timber is said to become incombustible, hard, and very lasting. M. Fontenay, C.E., in 1832, proposed to act upon the wood with what he designated _metallic soap_, which could be obtained from the residue in greasing boxes of carriages; also from the acid remains of _oil_, _suet_, _iron_, and _brass dust_; all being melted together. In 1816 Chapman tried experiments with _yellow soap_; but to render it sufficiently fluid it required forty times its weight of water, in which the quantity of resinous matter and tallow would scarcely exceed ⅟80th; therefore no greater portion of these substances could be left in the pores of the wood, which could produce little effect. M. Letellier, in 1837, proposed to use _deuto-chloride of mercury_ as a preservative for wood. M. Dondeine’s process was formerly used in France and Germany. It is a paint, consisting of many ingredients, the principal being _linseed oil, resin, white lead, vermilion, lard, and oxide of iron_. All these are to be well mixed, and reduced by boiling to one-tenth, and then applied with a brush. If applied cold, a little varnish or turpentine to be added. Little is known in England of the inventions which have arisen in foreign countries not already mentioned. M. Szerelmey, a Hungarian, proposed, in 1868, _potassa_, _lime_, _sulphuric acid_, _petroleum_, &c., to preserve wood.