Processes for Wood-preservation. 195 



camphor, the essential oils of lemon, bergamot, orange, lavender, 

 and rosemary ; and of coloring materials a neutral sulphate pre- 

 pared from indigo, and an aqueous solution of the coloring principle 

 of yellow-wood. Of resinous substances, he procured a considerable 

 absorption of spirits of turpentine, both pure and crude. By intro- 

 ducing the chlorides of lime and magnesia, he proposed to give an 

 unnatural elasticity and flexibility to wood : by using the deliques- 

 cent salts, he sought to render it incombustible ; and finally, by 

 using various solutions that give precipitates the base of which is 

 silica, he attempted to secure a kind -of petrification. 



773. He at first gave preference to the pyrolignite of iron, ob- 

 tained by exposing scraps of iron to the action of the crude acetic 

 acid obtained from wood by distillation. He afterwards abandoned 

 this for the solution of sulphate of copper, and instead of absorption 

 by the living tree, he injected the wood as follows : 



774. The logs still full of sap and with the bark still on, were 

 placed upon skids, and a collar fitted closely to one end. The solu- 

 tion was then forced through the pores, either by pumps cr by hy- 

 drostatic pressure, the wood being still fresh and full of sap. It is 

 found that solid woods, like the cherry, oak, etc., will not receive 

 the solution in the heart-wood, and that the process affords but par- 

 tial benefit; while in other kinds the success is very great, the 

 woods thus prepared lasting two, three, and even five times longer 

 as railway ties, and for other like exposures, than that which has 

 not been treated. This process has been largely ust d in France, 

 and its inventor, unlike many discoverers, realized its benefits in 

 his lifetime. He died in 1871, leaving quite a fortune acquired 

 from his patents. 



775. This process has been also much employed in Belgium 

 Germany, and Switzerland, in preparing fir timbers for telegraph 

 poles, and many other uses. After injection, the wood should be 

 seasoned before using, which it does very readily, becoming quite 

 light and portable. It is claimed that the sulphate of copper be- 

 comes fixed in the wood, somewhat like the mordant in dyes, so as 

 not to dissolve out in fresh water, although in sea water it appears 

 to gradually lose its antiseptic qualities by prolonged exposure. 

 The amount of this salt absorbed is found to be notably diminished 

 by the presence of iron, or of certain saline solutions, or of carbonic 



