PRESERVATION OF WOOD. 199 
iT. 
The measures above recommended must be observed if the subsequent steps 
are expected to result in success. We proceed now to describe the arrange- 
ments for conducting the process, which are very simple, and shall confine our- 
selves in the main to those intended for the preparation of railroad sills, merely 
noticing any differences which may exist in the case of materials intended for 
other purposes. 
All the logs designed for sills should be cut into pieces whose length so far 
exceeds that of a double sill as to admit of the renewal, at the time of the 
operation, of the surfaces at the ends of the pieces where the sap soonest grows 
dense and obstructs the passage of the injected fluid. For this excess a length 
of 30’ is enough if the tree, especially in hot weather, be felled but few days 
before the preparation. ‘To arrange the place of operation, we lay on a surface 
properly levelled four beams parallel to one another, with an inclination of 
za in the direction of their length, which length should be such that at least 
twenty logs may be placed across the beams at an average distance of 2’ 6 from 
one another. 
Along the outer beams channelled logs or troughs should be laid for the pur- 
pose of receiving the liquid as it escapes from the ends of the sill-pieces; and 
the two inner beams must be placed at such a distance from the middle line 
of the whole construction as to leave between them sufficient room for a channel 
destined to receive a leaden pipe, which connects with the vessel containing the 
vitriolic solution. ‘This pipe is furnished with copper taps at distances of 2’ 6”, 
corresponding with the middle of the sills which are to be impregnated. The 
fluid, which passes through the sills and falls into the channels provided for 
that purpose, is conveyed by them into a receptacle below the level of the gen- 
eral stage of operations, whence it may be drawn by a pump, and, if needed 
for further use, filtered and restored to its original strength. 
The impregnating fluid is contained in three vessels, which are stationed on 
a platform, at least 25’ high in the middle of the works, and which are furnished 
with faucets, issuing a little above the bottom of the vessels, in order that im- 
purities may have room to settle below the vent. Each of these faucets com- 
municates by means of an India-rubber tube with the leaden pipe, which ter- 
minates at the sides of the vessels in three branches. Near at hand is a pump 
to supply the water required for the solution. Of the three vessels, one is de- 
signed to feed the leaden distributing pipe; the second receives the water raised 
by the pump, or the fluid that has been already once used; in the third, the 
prepared fluid is allowed to rest, that impurities may be deposited. This last 
vessel is connected with the distributing pipe as soon as the first is emptied. 
The logs to be impregnated are laid upon the beams and wedged, so that 
their ends shall be perpendicular over the channelled logs or troughs, and their 
direction at right angles with the beams, Whatever may have been the lapse 
of time since the felling of the trees, the end surfaces of the logs should be re- 
newed, that the injected fluid may more readily pass through, besides that the 
requisite length may thus be given to the material. Everything being thus 
arranged, an incision is made with a saw in the middle of each log to the depth 
of ;*, of the vertical section in soft, and still deeper in hard woods. By means 
of a jack-screw the middle of each logis then slightly raised, whereby the incision 
will be opened, and not far from this incision, in each half of the log, a hole is 
bored obliquely from the external surface of the log through the face of the in- 
cision, which must be carefully freed from any chips or saw-dust. In the inci- 
sion we now lay a ring of cord or rope, the outer circumference of which must 
exactly correspond with that of the log; but, while thus preparing to close the 
opening, care should be taken that the ring do sot descend too deep into the 
