NOTES ON THE PROPERTIES OF WOOD. 9 



and solutions of metallic salts are employed instead. Among these M. 

 Boucherie's method has obtained the best results. He acts with a pressure 

 of 5 or 7 feet of water upon wood not later than two or three months 

 after it is felled, and injects a solution of sulphate of copper by a trans- 

 versal section, while the sap runs out in the opposite direction. Railway 

 sleepers prepared in this manner were laid down in 1846 ; and in 1853 

 they were found in so good a condition that ever since, M. Boucherie's 

 system has been much employed in France. Another economical process 

 of Mr. Fontenay is worth mentioning. He acts upon wood with what he 

 calls metallic soap, which he obtains from the residue in the greasing- 

 boxes of carriages ; also from the acid remains of oil, suet, iron and 

 brass dust, which are all melted together. 



A piece of wood was put in such a hot fluid for forty eight hours 

 after the water had previously been partly extracted under the ordinary 

 pressure of the atmosphere. When taken out, the metallic solution 

 which it had taken up stood at 3 per cent, to its first weight. This piece 

 of wood was used as a railway sleeper on the Orleans Bailroad, and after 

 eight months it was in perfect condition, whilst other wood not treated 

 in a similar manner was in a state of decomposition. 



Another process is recommended by Mr. Dondeine, and much 

 applied in France and Germany. It is a paint consisting of the fol- 

 lowing : — 



Linseed oil . . . .15 kilogrammes. 



Rosin 15 „ 



T ^ 5 



Zinc or white lead . .12 „ 



Vermillion, red or yellow .10 „ 



Colour (clay colours must be 

 avoided as they thicken too 

 much) .... 4 „ 



Cement .... 6 „ 



Oxide of iron 



Gutta percha, glue, or gum 



Hydrate of chalk . . 6 „ 



Lard 15 „ 



Litharge .... 2 „ 



(One kilogramme = 2,205lb. English.) 



All these are well mixed, and reduced by boiling to one-tenth. When 

 applied warm, it can be applied with a brush ; but not too hot. It may 

 also be used cold ; in which case the paste must be mixed with a little 

 varnish or turpentine oil. The results obtained with this process are 

 reported as yet very satisfactory. It prevents decay, and admits no 

 humidity. 



Mr. Dondeine further reports that it prevents oxydation of iron ; and 

 wherever walls have had a coat of this mixture it has kept away all wet, 

 VOL. iv. c 



