AN IMPROVED PROCESS FOR PENETRATING OR IMPREGNATING WOODS WITH VARIOUS SUBSTANCES
Year: 1865

page_text: PROVISIONAL SPECIFICATION left by William Edward Gedge at the
Office of the Commissioners of Patents, with his Petition, on the 9th
June 1865. A communication from abroad by Jules Louis Hossard,
of 39, Faubourg St. Martin, Paris, France.
I, WILLIAM EDWARD GEDGE, of the Firm of John Gedge and Son, of No. 11,
Wellington Street, Strand, in the County of Middlesex, Patent Agent, do
hereby declare the nature of the said Invention for "AN IMPROVED PROCESS
FOR PENETRATING OR IMPREGNATING WOODS WITH VARIOUS SUBSTANCES," a
communication to me from abroad by Jules Louis Hossard, of 39, Faubourg
St. Martin, Paris, France, to be as follows:-
This Invention consists in causing the penetration of woods by absorption
in the passage from heat to cold. The Inventor of this improved method
thought that instead of succeeding by the difficult process of pressure to
push into the pores of the wood a liquid which broke the contexture of its
fibres without penetrating deeply into it no more than the penetration effected
in woods somewhat thick and hard by immersion, during many hours, in baths
heated to a high degree, he might by absorption cause to easily and rapidly
penetrate to the heart of the most compact wood, oak or box even, every
sort of substance in solution, such as metallic or other salts, to give it greater
density, as well as dyes to color it interiorly, or fat oils to preserve it from

page_text: damp. This improved process is based on a principle of nature, namely, that
porous bodies in condensing by cold after having been greatly dilated by heat,
of themselves absorb the liquid in which they are plunged, as do plants
during the night, and thenceforth fill all the channels, which they possess in
infinite number and which had emptied themselves the dilatation of the air,
or by the evaporation of the sap or of the vegetable juices. This means,
therefore, consists in first heating to the highest possible temperature the
wood that is to be prepared, having recourse for that purpose to steam
receivers, where the wood may acquire a heat that will not, so to speak,
permit it to be touched by the hand, or simply in baths raised (in well closed
boilers) to the highest boiling point, the bath being simply water, and from
which at the end of two hours at most for the thickest logs, and scarcely
fifteen minutes for deal planks or espalier laths, these pieces are withdrawn to
be plunged immediately into wooden vats in which are prepared baths with
the substance or the solution which is to penetrate the wood, but entirely cold,
and the liquid of which is thenceforth absorbed by the pores of the planks,
stakes, or logs, as they condense. Their immersion must be complete, and last
about 24 hours, so that they may pump during the coolness of the night,
and be withdrawn in the morning as impregnated as possible with the
preserving liquid; in fact after this lapse of time they will be impregnated to
that degree that the woods, whatever their nature, will keep at the bottom of
the liquid like a stone, whereas, if prepared by the other injections they
always float, no matter how. long they are left in the boiling liquid which
simply causes the dilatation of the conduits and does not permit them to
absorb. This is very simple, and might be partially effected by permitting the
bath to cool in the boilers with the liquid intended to penetrate it; but not
only has it not been thought of, but it would be very costly to have to
re-commence heating each time for only a few pieces which would remain, to
occupy the boiler for several days, as the cooling would then take place, but
very slowly, and many boilers would have to be fitted up, whereas the wooden
vats for the condensation may be infinitely multiplied without great expence.
This Invention therefore rests entirely on the principle of absorption by all
porous bodies in their passage from heat to cold during their immersion in the
liquor, or the substance with which it is desired to impregnate them. I would
add that besides the injections suitable to preserve woods, dye them in the
interior, or impregnate them with fat oils, this improved process may also be
used to penetrate them with earthy mineral salts or others of a nature to
preserve them from combustion, an important object for timber framings and
building purposes generally. The penetration however will always take place

page_text: better in green woods or timber not long felled, than in seasoned woods which
have contracted in drying, and no longer have channels or conduits open to
receive and absorb the liquids, such above all are oak and the firs, which
nevertheless inject perfectly when freshly cut. If some (pieces of wood are
not penetrated thoroughly by a first operation, which will be sufficiently
indicated by their weight, which on leaving the cold bath should be about one-
third more than before they were heated, they can be submitted to a second,
which will never fail to give the most satisfactory result, more especially if
they are left to cool for a long time in the liquid for the introduction of which
the way has been as it were prepared by the first operation. Boilers thoroughly
tight, and which can without danger bear a steam pressure of two or three
atmospheres, will be the most suitable to quickly penetrate with heat large
pieces of wood.