466 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ing dry rot and decay, and for rendering the softer kinds of 

 timber as bard and durable as oak or teak. The process con- 

 sists in impregnating the timber with a hot solution of tung- 

 state of soda, the expense being estimated at about six cents 

 per cubic foot, and probably less when a large quantity is 

 treated at one time. It is stated that the trials that have been 

 made are perfectly satisfactory, and that the British govern- 

 ment has entered into an agreement with the patentee for 

 the use of the method in the government yards. 2 A, June 

 26,805. 



PRESERVATION OF TIMBER BY LIME. 



The use of lime for the preservation of wood, especially 

 for railroad purposes, has lately been urged by Lostal, who 

 simply piles the planks in a tank, and places over all a layer 

 of quicklime, which is gradually slaked with water. Tim- 

 ber for mines requires about a week to become thoroughly 

 impregnated, and wood for other purposes more or less time, 

 according to thickness. It is claimed that wood prepared in 

 this way acquires a remarkable consistency and hardness, 

 and will never rot. Beech wood has been prepared in this 

 way for hammers and other tools for iron-works; and it is 

 said to become as hard as oak without losing its elasticity 

 or toughness, and to last much longer than when unprepared. 

 3 A, April 24, 523. 



PRESERVATION OF WOOD BY MEANS OF IRON. 



According to Hubert, iron has always been recognized as 

 the best preservative for wood, and the difficulty in its appli- 

 cation does not lie in the impregnation of the wood with it, 

 but in the retention of it in the wood in its most effective 

 form as hydrated sesquioxide, which not only displaces the 

 albumen and other nitrogenous matter, but also renders the 

 wood unfit for the support of insects. Copper, although of 

 great value in this respect, may be dispensed with, and it is 

 not applicable in earth containing ammoniacal matter. It is 

 sufficient, in order to impregnate wood with iron, to drive 

 into it long thin nails with broad, flat heads. These, upon 

 rusting, when the wood is placed in the ground, continually 

 distribute iron through the whole mass of the wood. If 

 preferable, the wood may be wound with iron wire. Wood 



