86 
\\ per cent, solution of chloride of barium. It is bard to conceive how 
the second solution could euter the pores already filled with the solu- 
tion of sulphate of copper, and where the chloride of barium reached 
the first solution it left chloride of copper, the value of which as an 
antiseptic is uncertain, and some sulphate of barium inside of the wood, 
which could do neither good nor harm. The treatment of the paving 
blocks at Cleveland was evidently more rational, because by the Bou- 
cherie process the wood was well impregnated with sulphate of copper, 
and the soaking in chloride of barium only produced an interchange 
near the ends, where the formation of the insoluble sulphate of barium 
was of the greatest benefit in stopping up the pores to some extent, 
and if not preventing, at least impeding, the ingress of water and the 
washing out of the sulphate of copper from the inside. 
Mr. Thilmany later used sulphate of zinc, instead of copper, in connec- 
tion with chloride of barium, but the process does not appear anymore 
rational. If the interchange of the chemicals throughout the lumber 
could occur, it would leave the wood impregnated with chloride of zinc 
and sulphate of barium ; but as such a complete interchange is .im- 
possible, part of the sulphate of zinc would undoubtedly remain un- 
changed, and as its antiseptic powers are not established, the result as 
to preservation must be uncertain. 
2. The Wellhouse Process. — Another device for preventing the removal 
of the zinc chloride has been invented by Mr. Wellhouse and is exten- 
sively used. It is based on the fact that glue and tannin, brought to- 
gether in proper proportions, will form a substance resembling leather. 
The timber is steamed in the usual manner, inclosed in a vacuum, then 
impregnated by pressure with a solution consisting of chloride of zinc 
and glue 3 and afterwards subjected to a bath of tannin under pressure. 
The impregnation with glue, it is claimed by the president of the com- 
pany using this process, will destroy all tannic acid within the wood. 
But the benefit derived from this chemical combination is not appar- 
ent, since tannin is rather a preservative than otherwise. The bath of 
tannin, the president further states, precipitates the glue remaining in 
the outer pores of the wood, retaining a greater percentage -of chloride 
of zinc in the wood than would be the case if it were simply Burnett- 
ized. But while the latter claim may be substantially correct, it remains 
to be seen whether the introduction of an uncombined organic substance 
into the inside pores will prove favorable to preservation. 
The question whether the zinc tannin process gives better results 
than the ordinary Bethell process will be decided within a few years, 
as a number of works for treating ties by this process have lately been 
Constructed by the Atchison, Topeka and Santa Fe Bailroad at Las 
Vegas, 3s. Mex., and by the Union Pacific Bailroad at Laramie, Wyo., 
and the process is also used for preserving ties for several railroad 
companies at the Chicago works of the company. 
