106 PRESERVATION OF TIMBER. 



friction ; nor do they always remove the causes of internal decay 

 on the contrary, by preventino: more complete dryness, they some- 

 times even provoke or favor them, when applied to tender, that is, 

 im|jerfecrly seasoned wood. Merely laid on the surface, indeed, it 

 h-is always been seen that varpishes of any kind were but indifferent 

 protectors ; that a really good preserver ought to penetrate the sub- 

 stance of tic wood, and unite with ihe tissue itself. IJut herein lay 

 the whole difficulty ; how was the needful penetration to be effected ? 

 for the number of chemical substances, from which good effects 

 might reasonably be anticipated, is pretty considerable, — unless in- 

 deed we find ourselves prevented from using them by the considera- 

 tion of the price; for it is imperative that any preservative proposed 

 be extremely cheap. 



For a long time the only process for elTecting the penetration of 

 timber by substances proposed tor its preservation was to mucerate 

 them for a longer or shorter lime in a solution of the substance. 

 But this means was found as tardy of accomplishment as it was or- 

 dinarily imperfectly effected ; to have got to the heart of logs of 

 large scantling, years would have been required. Any delay, how- 

 ever, in such circumstances, is of itself a cause of enhanced price 

 of the article. By and by a variety of processes, the elen\ent in one 

 being pressure, in another exhaustion, were put in practice, and very 

 satisfactory results obtaincil. M. Breant showed, that by mt-ans of 

 strong pressure he could fill the largest loj^s from one end to the 

 other with any unctuous or resinous substance propose.!, in the course 

 of a few minutes. M. Moll, a learned German, proposed creosote 

 introduced in the state of vapor by forcing, as an etfectual means of 

 preserving timber, which it probably would be found ; but the high 

 price of the antiseptic, were there nt) other objections, would neces- 

 sarily be an obstacle to its general employment. TIjc same o!)jection 

 applies to the bichloride of mercury, (Kyan's patent ;) and arsenic is 

 inadvisable from its deleterious effects upon the animal economy. 

 Some workmen are said to have lost their lives in conseipience of 

 working timber which had l)een impregnated with a solution of while 

 oxide of arsenic. 



It had been observed that vessels enjrageil in the lime-lrade lasted 

 long; and then it was naturally lhouj,'hl that by impregnating the 

 wood to he used for ship-buildinij with lime it would be rendered 

 more durable. But the result did not answer expectation ; the tim- 

 ber treated with lime did nt)t even seem to last the usual time.* 

 ( Such was the state of the question when Dr. Bouiherie made a 

 highly important communication to ihe Koyal Academy of Sciences 

 on the preservation of tnnber.t Some estimate of its nature may 

 be formed trouj the list of subjects discussed in this remarkable 

 paper. 



1. To protect timber against dry-rot and the ordinary wet-rot. 



2. To increase its hardness and strength. 



3. To preserve its flexibility and elasticity. 



• Dupin. Ann. de Chimio, t. xvil. p. 280 

 t l«lcni. t. Ixxiv. p. 113. 



