73 
the wood was drawn into the suction chamber, and thence into the 
main suction pipe and vacuum tank, thus forming a vacuum inside the 
ducts of the log, which caused the sap and the solution from the lower 
chamber to follow in a solid column and gradually to fill tin 1 wood with 
the antiseptic solution. 
Another method was to place the logs in a triangular tank in such 
a manner that the lower end of the log, to which in this case nochamber 
or cap was fixed, would be completely submerged in the solution. When 
the cock controlling the connecting pipe was opened the air and sap 
contained iu the log were exhausted from it and the cells gradually 
tilled with the solution. In some cases the tank was first filed with 
water for the purpose of washing out the sap before the antiseptic solu- 
tion was used. 
The antiseptic generally used was sulphate of copper, because its 
presence or absence can be determined constantly by the application of 
a solution of ferrocyanide of potassium, and the experiments were in- 
stituted mainly for the purpose of ascertaining how long a time was re- 
quired to thoroughly impregnate the logs. 
With sound logs, of 12 to 20 inches diameter, cut into lengths of 8 
feet, it was found that the wood was thoroughly impregnated in from 
five to eight hours. This was ascertained by sawing the log in two after 
it had been treated and testing the whole surface of the cut with the 
reagent. 
But when the logs were not perfectly sound the impregnation was 
imperfect. / ; . , . .alto taU &svmi Ji "lp doHioif 
A small experimental station was afterwards erected near Charleston, 
in Southeast Missouri, where it was intended to test the commercial value 
of the process, and a number of large logs, mostly Sweet Gum, were im- 
pregnated. But as this kind of timber contains a great deal of sap 
wood, and as most of the large logs show incipient decay at the center, 
the results were not nearly as favorable as those which had been 
attained by the previous experiments with logs cut from other kinds of 
timber of smaller diameter, sound and of uniform texture. 
The experiments were interrupted by the illness of my son, who had 
charge of the work, and a season of high water, which kept the ground 
at the works, and for miles around, submerged for several months, in- 
duced me to discontinue the experiment altogether. 
But I believe that under proper condition the method just described 
will cause a more thorough impregnation of wood than can be secured 
by any other, without the necessity of an expensive plant and without 
injury to the strength of the timber. 
I believe also that it might be used to good advantage in works where 
now steeping alone is relied upon, with a view of expediting the process 
and of impregnating the timber not only near the surface, but also 
deeper. The timber, when submerged in the antiseptic solution, might 
be fitted at one end with a metal cap, as heretofore described, and the fluid 
