10 
On the Preservation of Timber. 
through the upper surface into the space left by the slit, into 
which a tube is inserted for conveying the liquid, which, by 
degrees, insinuates itself through the whole mass of the wood. 
Perrin has further modified the application of the same 
principle by fitting on to the end of the trunk a cast-iron 
cylinder, in which he rapidly forms a vacuum by igniting a piece 
of tow steeped in naphtha. The other end of the trunk being 
immersed in the preservative liquid, the atmospheric pressure 
forces it through the whole length, in one or more similar 
operations. 
Bethell employs the same principle, in this manner : — he places 
the wood in an upright position in an air-tight tank nearly filled 
with the solution, and then exhausts the air, so as to allow the 
preservative liquid to fill the pores ; or he substitutes a water- 
proof bag attached to one end of the wood, and forces the liquid 
through the wood by some artificial pressure. 
Uzielli, Newton, and Le Gros, as well as Bethell, simply place 
the lower end of the tree (felled when the sap is rising, and after 
the bark has been removed j, in their different solutions, and allow 
the liquid to ascend by capillary action. 
Renard differs from the preceding, in placing one end of the 
wood in a trough containing his solution, and attaching a plate 
by a leather washer at a little distance from the other end. In 
this plate there is a tube fixed in connection with an apparatus, 
in which a vacuum can be produced, thus bringing the atmospheric 
pressure into operation. 
Class YI. Penetration by Descent. — Uzielli, in another patent, 
recommends that the waterproof bag or sack should be applied 
at the upper end of the tree or timber, and he employs the 
pressure of the preservative liquid to force out the sap at the 
lower end. 
Drying Wood. — In many of the preceding plans it is recom- 
mended that the timber should be dried before and after impreg- 
nation with the various preservative liquids. A very effectual 
method of rapidly accomplishing this object has been patented 
by Barlow, which in some measure may be classified here. 
He attaches a metal plate by screws to the end of the piece of 
timber, and packs the edges by a ring of vulcanized india-rubber. 
(Fig. 5.) He forces air into the intervening space, which ex- 
pels the sap or preservative liquid and dries the timber ; or 
he exhausts the air, and the atmospheric pressure produces the 
same effect in a contrary direction. 
In concluding this part of the subject I may refer to the 
last and most complete mechanical arrangements of the late 
M. Boucherie, which embrace many of the principles ex- 
