16 ADDRESS BY THE PRESIDENT, NOVEMBER 3, 1875. 



their durability to the same causes, namely, thorough drying by 

 exposure to air, without being covered with paint or plaster. 



Various means have been adopted for preventing timber from 

 being attacked by dry rot. Boucherie's method was to cause grow- 

 ing trees to absorb fluids of different kinds, which he considered 

 as acting on the contents of the woody tubes, in such a way as to 

 render them less liable to disease. The solutions he employed 

 were acetate of lead, pyrolignite of iron, and corrosive sublimate. 

 He also found that trees, immediately after being cut down, when 

 their extremities were immersed in these solutions, absorbed them 

 with rapidity. A tree having been sawn near the root, is placed 

 in a horizontal position, and a cap of leather or waterproof cloth 

 is tied firmly over the lower end, leaving a sufficient space for the 

 solution. This is introduced by a flexible tube luted to the 

 leathern cap, and communicating with a barrel, placed at some 

 height above the timber, so as to give the pressure of a column of 

 six or eight feet. The liquid is put into the barrel. In this 

 way twenty or forty gallons of the solution of acetate of lead may 

 be made to filter through the pores of the wood. Mr Hyett 

 adopted Boucherie's method, and has given colours to timber, by 

 making the wood absorb in succession fluids (such as solutions of 

 ferrocyanuret of potassium and sulphate of iron), which, by their 

 combination, produced a coloured compound. 



Timber, after being cut, has been subjected to various processes 

 for the purposes of rendering it durable. Kyanising is performed 

 by subjecting the wood to the .action of corrosive sublimate, by 

 means of which it is probable that the albuminous matter is coagu- 

 lated, fermentation is prevented, and hence the wood is rendered 

 less liable to decay and to the attacks of fungi Kyan's solution 

 is made to pass rapidly through wood in vacuo. Sir William 

 Burnett found that the application of chloride of zinc to vegetable 

 matters, such as wood and canvas, had the property of effectually 

 guarding them against all the ordinary causes of destruction, with- 

 out communicating any bad property to the substance prepared 

 from it. Canvas so acted on was kept long in damp cellars, and 

 exposed to various vicissitudes, without being injured, while ordi- 

 nary canvas, in similar circumstances, became rotten. The pro- 

 cess has received the name of Bumettising. Burnett's antiseptic 

 solution, of one pound of chloride of zinc to five gallons of water, 

 has been tried in Woolwich Dockyard with success. 



Mr Bethell uses creasote for the preservation of wood. The 



