THE PRESERVATION OF WOOD FROM DECAY. 85 
he adopted the cylinder of Breant. Unfortunately, however, copper sulphate is 
not applicable to Avood under all circumstances. Baist" has shown that it fully 
protects only green wood containing much sap, and Boucherie, Jr., somewhat 
corroborates this statement. Kirschweger,^'' also, claims that freshly cut wood is 
best for treatment with this preservative. This may perhaps enable us to explain 
the failure cited by Dalpiaz,^^ who says that on the Paris and Rouen Railroad, 
the timbers of a bridge which had been prepared with copper sulphate decayed 
with unusual rapidity. Either the wood was in an improper condition when 
treated with the sulphate, or else the impregnation was not carried out consci- 
entiously. One other point remains to be noticed. According to Koenig," resin- 
ous woods retain this antiseptic better than those which are non resinous. From 
the latter the sulphate may be partly, at least, washed out, while in the former it 
seems to be fixed by the resin, probably in the form of some basic compound. 
The resin itself, however, is a preservative. 
The testimonials to the efficacy of copper sulphate in preserving wood are 
quite numerous. In some of the German mines it has been found to give even 
better results than the zinc chloride.^" But on certain German railways, where 
it had been employed for the protection of sleepers, it was found to attack the 
iron. On the other hand, it is said that if the sleepers be thoroughly dried after 
impregnation, no such objectionable result will follow. In 1855, the Jury of the 
French Exposition put forth an extremely favorable report concerning Boucherie's 
process, asserting not only its value, but also its superior cheapness over the plan 
of creosoting." In 1846, about eighty thousand sleepers saturated with copper 
sulphate, together with some which were unprotected, were laid down on the 
Northern Railway of France. In 1855, nine years afterward, the prepared sleepers 
were as good as ever, the others having long been decayed and replaced by new 
ones. For preserving telegraph posts, copper sulphate has been similarly effect- 
ive. The saving to French lines alone, up to 1855, was estimated at two and 
a half million of francs." Examples of this sort could easily be multiplied, but 
one more will suffice. In 1868, Boucherie, Jr.," exhibited to the French Academy 
specimens of wood which had been prepared according to his father's process, 
and exposed since 1847. These specimens, after twenty-one years of exposure, 
were as sound, as elastic, and as strong as when new, and readily yielded the 
reaction of the copper they still contained. 
In England and America the chloride of zinc has probably been used much 
more largely than any other metallic salt for the preservation of wood. Having 
been introduced by Burnett in 1838, its application to wood is known as " bur- 
nettizing," and the wood thus prepared is said to be "burnettized." The solu- 
11 Dingl. Pol. Jour., 162, 397, 1861. 
12 Dingl. Pol. Jour., 122, 223, 1851. 
13 Dingl. Pol. Jour., 120, 140, 1851. 
14 Sei.-Amer. , 5. Dingl. Pol. Jour., 160, 48, 1861. 
15 Dingl. Pol. Jour., 202, 174, 1871. 
16 Jour. Frank. Inst., 32, 1, 1856. 
17 Comptes Rendus, 67, 713, 1868. 
