PRESERVATION OF TIMBER. 113 



include a large quantity of air in their tissues ; in this case the flow 

 does not go on until this air has heen expelled ; once begun, it goes 

 on without interruption. The operation is terminated when the 

 fluid, which drips from the lower part, is of the same nature as that 

 which is entering above. In my opinion this method must be pre- 

 ferable to that by aspiration. In the second mode of proceeding, in 

 fact, we accomplish our object by a true displacement ; almost the 

 whole of the sap is expelled, and the saline solution introduced has 

 only to subdue or neutralfze the very small quantity of soluble 

 organic matter which may remain adhering to the woody tissue. 

 By accomplishing such a displacement by means of simple water w« 

 should undoubtedly obtain results favorable to the preservation of 

 timber, inasmuch as we should have freed it from almost the whole 

 of those matters which are regarded as the most alterable them- 

 selves, and the first cause of rotting in timber. The rapidity with 

 which the fluid introduced is substituted for the sap which it dis- 

 places, and the quantity of this expelled sap which may be readily 

 collected, exceeds any thing that could have been imagined before 

 making the experiment ; thus the trunk of a beech-tree about 52^ 

 feet in length by 33^ inches in diameter, and consequently forming 

 a cube of somewhat more than 29 feet and a half, gave in the course 

 of twenty-five hours upwards of 330 gallons of sap, which were re- 

 placed by about 350 gallons of pyroligneous acid. The liquid which 

 penetrates in this way acts so effectually in displacing the sap, that 

 M. Boucherie says we can readily procure or extract by its means 

 the saccharine, mucilaginous, resinous, and colored juices contained 

 in trees. It would, perhaps, be possible, and I beg to suggest this 

 idea to colonial planters, to apply the method of displacement to the 

 extraction of the coloring matters of dye-woods. The trade in dye- 

 woods does not extend beyond localities favorably situated for ex- 

 portation, so that at a certain distance from the shores of the ocean, 

 or the banks of rivers, it is found absolutely impossible to carry on 

 a trade, the material of which is so heavy and bulky as timber. 

 The greater number of the coloring matters found in wood^ being 

 soluble, it is possible to export them in the state of extract. Various 

 attempts of this kind have already been made, and if they have not 

 been successful, the obvious cause of this lies in the method which 

 has been followed, and which has hitherto consisted in treating the 

 wood reduced to chips by means of boiling water, and then reducing 

 the colored solution obtained ; but it is obvious that in the remote 

 forests of America, or of Africa, where all mechanical means are 

 wanting, nothing but failure could attend upon such a procedure. 

 By the method of M. Boucherie, the main difficulties appear to be 

 got over ; there is nothing more to be done, in fact, than to get the 

 trees into the state of logs, and these are generally readily trans- 

 portable, after which one or more evaporating pans seem all that 

 are further necessary. 



Dye-woods. — The greater number of these woods belong to the 

 family of leguminosaj ; the principal kinds met with in trade are : 



I. Mahogany wood, {hmnatoxylon campechianum,) of a reddish 

 10* 



