the felling. The power by which it is deter- 
mined declines rapidly after the first day is 
passed, and by the tenth day it is almost en- 
tirely gone. In favourable circumstances these 
ten days suffice to effect the complete im- 
pregnation of the largest stem. In one of his 
experiments upon a poplar, M. Boucherie saw 
the absorbed liquid reach the height of about 95 
feet in seven days.—In the white woods, it is 
found that there is an axis of variable diameter 
in different cases which escapes or rather which 
resists impregnation. In hard woods, the parts 
which are not penetrated are the inner or un- 
dermost circles of the heart. M. Boucherie, 
after having ascertained these facts, explains 
them thus: in the white woods, according to 
the testimony of the workmen, the central part 
which resists the penetration is at once the 
weakest and the most perishable portion of the 
log; there is no longer any circulation, any life 
there; it is dead wood interred in the midst of 
the living woody layers. This absence of pene- 
tration of the woody tissue appears on some oc- 
casions elsewhere than in the centre of the trunk 
and branches; it presents itself under the most 
various forms and in different parts of the trunk; 
it appears to depend, as has been said, on the 
presence of wood abstracted from the influence 
of vital phenomena, and which, impenetrable 
itself, presents a barrier or an obstacle to the 
_passage of the solution to other parts; it is thus 
that a knot, or a piece of rotten wood, is gener- 
ally found as the starting point of the zones that 
have escaped imbibition. As to the non-pene- 
tration of the most central parts of the heart of 
oak, elm, &c., M. Boucherie views it as affording 
unquestionable proof of the fact that there the 
living juices of the tree had long ceased to cir- 
culate. 
“The distinction generally drawn between the 
white or soft, and the perfect or hard wood, rests 
on the differences of colour presented by a trans- 
verse section of the trunk. In the oak, for ex- 
ample, the external and nearly white concentric 
layers are held as the soft and valueless portion of 
the log, and are commonly hewn away in squaring 
it; the darker more central portions. constitute 
the heart-wood, the valuable timber. But ac- 
cording to M. Boucherie, the distinction is dif- 
ferent when the fact of penetrability is taken as 
the guide, and all that portion of the trunk 
which imbibes is considered as alburnum or soft 
wood, and all that does not imbibe is regarded 
as hard wood. The alburnum in this way is so 
much extended that it may be found constitut- 
ing three-fourths of the whole mass of the trunk. 
Once introduced, the pyrolignite of iron, accord- 
ing to M. Boucherie, is not only useful in pre- 
serving the wood, it also increases the density of 
the timber. Impregnated with this salt of iron, 
wood becomes so hard as powerfully to resist the 
tools of the carpenter and joiner, who even com- 
plain of the increased difficulty with which it is 
TIMBER. 459 
worked.—Flexibility and elasticity in timber are 
qualities in request for certain purposes, parti- 
cularly for ship-building. The fir timber of the 
north of Europe is much more prized than that 
of the south, especially for masting, on account 
of its greater flexibility and elasticity, qualities 
which appear to depend in a great measure on 
the quantity of moisture retained; to increase 
these qualities M. Boucherie has even introduced 
by imbibition a deliquescent salt, such as the 
muriate of lime, which retains moisture power- 
fully as is well known, and seems to have the 
power of giving a remarkable degree of supple- 
ness to wood. The experiments, contrived to 
show the effects of deliquescent salts were made 
upon deal, which is allowed to be one of the 
most brittle woods. After having impregnated 
it with concentrated solutions it was sawed into 
very thin veneers, some of which I have seen in 
the possession of M. Boucherie, which after being 
strongly twisted and bent in various senses, im- 
mediately regained their original flatness and 
evenness when they were left free—Warping or 
shrinking is occasioned by alternate shrinking 
and swelling in consequence of varying hygro- 
metric states of the atmosphere. After having 
found that this did not begin to take place until 
the timber was upon the point of losing the last 
third of the moisture which it contained at the 
time of being cut, M. Boucherie thought that to 
prevent all warping and shrinking it would be 
enough to retain this quantity of water in com- 
bination with the woody tissue, in other words, 
to prevent complete desiccation. Facts have 
proved the correctness of this view. Pieces of 
wood kept at a certain unchanging degree of 
moistness by means of a deliquescent salt infused 
into their pores, do not change their bulk or 
form, in spite of extreme variations in the hy- 
grometric state of the air. Such pieces of wood, 
however, exhibit great differences in point of 
weight under the influence of different circum- 
stances. Several planks of great breadth and 
extremely thin were prepared with chloride of 
lime and joined together; some of them were 
left unpainted, others were painted on one side, 
or on both sides; after the lapse of a year these 
planks were found not to have shrunk or warped, 
whilst similar planks of the same thickness and 
kind of wood, but unprepared, were found to 
have cast in an extraordinary way.—M. Bou- 
cherie has done more than this: he has not only 
had it in view to preserve wood and to prevent 
it from warping, qualities so desirable, he has 
made use of the same faculty of imbibition to 
impregnate the wood with a variety of beautiful 
colours, and thus to give even the most common 
kinds tints that will admit of their being used 
in the construction of costly furniture. The 
pyrolignite of iron alone gives an agreeable 
brown tint that harmonizes excellently with the 
natural colour of the harder parts of so many 
trees which usually resist penetration. By fol- 
Wp SE 
