TIMBER. 
commissioned by the French ministry to take 
information on the subject, reported that the 
ravages committed by these insects had been 
But it is principally in. 
very considerable. 
warmer climates, where the temperature is 
steady throughout the year, and where there is: 
no winter, that the thermites occasion the most 
alarming injury, At Popayan, for example, it is 
dificult to meet in a building, even of recent 
construction, with a piece of wood which is not 
gnawed and ant-eaten. The hardest and most 
compact woods do not always resist the attacks 
of these insects, which, farther, do not spare 
every kind of odorous wood, cedar for instance. 
—The dry-rot, which results from the develop- 
ment and growth of cryptogamic plants upon 
wood, is the curse of navies. Mr. Knowles is of 
opinion that this disease of timber has been 
known from the most remote antiquity; he be- 
lieves that he can even recognise dry-rot in the 
sore called house-leprosy, mentioned in the 14th 
chapter of Leviticus. A ship attacked by dry- 
rot, becomes in a very short space of time unfit 
for sea. The Foudroyant of 80 guns is often 
quoted as an instance of its destructive powers; 
launched in 1798, she had to be taken into dock 
and almost rebuilt so soon as 1802. The fungi 
which induce dry-rot have been studied by Sow- 
erby. Mr, Knowles signalizes two species in 
particular; one of which he describes under the 
name of Xylostroma gigantewm, the other under 
that of Boletus lacrymans. The xylostroma does 
not extend beyond the part where it is developed; 
but the boletus, on the contrary, is propagated 
with frightful rapidity, and disorganises deeply 
and to a great distance around the texture of 
the wood where it once appears. These fungi 
are generally found on board ship, between the 
planking and the ribs, in damp situations, and 
where the air is scarcely, if ever, changed. See 
the articles Bostricuipa, Dry-Roz, and Funai. 
The preservation of timber is a problem of 
eminent importance to vast multitudes of prac- 
tical men, and involves great elements of national 
prosperity, and has been a subject of grave and 
varied investigation on the part of many distin- 
guished philosophers. One remarkable, method, 
resulting from modern invention, is noticed in 
our article Kyanizine; and another, that of M. 
Boucherie, professing to protect timber against 
both dry-rot and the ordinary wet-rot, to increase 
its hardness and strength, to preserve its flexi- 
bility and elasticity, to counteract its alternate 
contraction and expansion under varying condi- 
tions of the atmosphere, to diminish its inflam- 
mability and combustibility, and to give it a 
variety of permanent colours and odours—may 
here be explained, historically and descriptively, 
in the words of Boussingault-—“In the whole 
of his experiments, M. Boucherie set out from 
this proposition, the truth of which appears in- 
disputable and to require no comment, viz.: 
That all the changes which wood undergoes pro- 
ceed or depend upon the soluble matters which 
it contains. In conformity with this idea, the 
first step towards giving durability to timber 
was, either to render these matters insoluble and 
inert, or to remove them entirely. M. Bou- 
cherie, therefore, in his first trials sought to 
render the matters insoluble by charging the 
wood with a substance capable of combining 
chemically and forming a precipitate with the 
soluble matter left by the sap. To resolve this 
problem, M. Boucherie investigated the reactions 
between the soluble matter of wood, which it was 
his object to precipitate, and a variety of low- 
priced chemical agents. He found that the py- 
rolignite of iron combined the greatest number 
of desirable properties; it is very cheap, the 
oxide of iron forms stable compounds with the 
greatest number of the organic substances which 
are found in the sap of vegetables, and to con- 
clude, the crude pyrolignite contains a notable 
quantity of creosote. The facts upon which M. 
Boucherie relies as proving the preservative 
powers of the pyrolignite of iron flow from nu- 
merous experiments performed either on vegeta- 
ble substances which in themselves readily and 
rapidly undergo changes, or upon billets of wood 
of different kinds. A quantity of flour, the pulp 
of carrots, beet-roots, &c., impregnated with the 
pyrolignite resist decomposition in a very re- 
markable manner in contrast with the same 
substances when they have not been prepared 
in any way. The wood which was selected for 
trial, was generally of the most perishable kind. 
In December 1838, several empty hogsheads and 
barrels made of the best timber, unimpregnated 
and impregnated with the pyrolignite, were 
placed together in the dampest parts of the 
great cellars of Bourdeaux. In August 1839, it 
was easy to see that the unimpregnated tubs 
were already deeply stricken, and after from two 
to three years they fell to pieces with the slight- 
est force; the casks made of the prepared wood, 
however, were as sound as on the first day of the 
experiment. M. Boucherie concluded from his 
experiments instituted with a view to the set- 
tlement of the question, that about th of the 
weight of the wood in its green state of the pyro- 
lignite was adequate to precipitate and render 
insoluble all the principles obnoxious to change, 
which were contained in the woody tissue. M. 
Boucherie, whilst he regards the pyrolignite of 
iron as at once the most powerful and one of 
the cheapest preservatives of timber, neverthe- 
less indicates several soluble salts, which are 
readily available in consequence of their low 
price, and also very effectual when the wood, 
which they are to preserve, is not kept con- 
stantly wet. Solutions of common salt, of chlo- 
ride of lime, the mother-water of salt-marshes, 
&c., were all tried and found useful. Casks, the 
wood of which had been prepared with the chlo- 
rides, after having been long kept in very damp 
cellars, came out as fresh as those which had 
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