Scientific Intelligence. — Arts. 203 



cient : thus, gg'gg and even ^^^^ of caustic potash in water, 

 will preserve from oxidation bars of iron, &c. immersed in 

 it. Lime-water, diluted with its own weight of water, or, of 

 course, without dilution, answers the same purpose. Alkaline 

 carbonates and borax have the same effect, but they must ne- 

 cessarily be stronger. 



21. On the Prevention of Dry-Rot, — At a meeting of the 

 Royal Institution, after adverting to the extensive decay of 

 wood in ships, houses, and other structures of that material, 

 involving a loss of such magnitude, as to have excited almost 

 universal search after a remedy, Mr Faraday said he should 

 pass by all propositions for its prevention, except that one ab- 

 solutely introduced by Mr Kyan, and to which Mr Faraday 

 had paid particular attention. The process is now largely in 

 use. The wood, prior to its application, is immersed in a 

 solution of corrosive sublimate ; in the course of a week, a load 

 of it is found to have absorbed five gallons of solution ; at the 

 end of that time it is removed, and shortly after becomes fit for 

 building. The preservative powers of corrosive sublimate in 

 furs, stuffed birds, anatomical specimens, &c. are well known ; 

 and those which it exerts over wood seem to be not less decisive, 

 and far more useful. Pieces of timber thus prepared were put 

 into a fungus-pit at Woolwich for three years, and at the end 

 of that time taken out perfectly sound. Canvass and calico, 

 treated in a similar manner, were also found to be preserved 

 from mildew and decay. Mr Faraday's suspicions appear to 

 have been excited, not so much as regarded the preservative 

 power of the process, but the healthiness of the wood, canvas, 

 8ec. impregnated by it ; and he required that such prepared ma- 

 terials should be thoroughly washed, and then submitted to a 

 test for proving the power of resisting decay. He found, after 

 calico and canvass had been washed in water until all the solution 

 which that fluid could remove had disappeared (mercury was 

 still present), such prepared materials were preserved in a damp 

 cellar, while the unprepared went rapidly to decay. Having 

 ascertained this combined state of the mercurial preparation, 

 Mr Faraday expressed his opinion, that the organic substances 

 could be well preserved by it without deriving any unwholesome 

 quality to deteriorate their ordinary application. 



