PRESERVATION OF WOOD. 203 
sufficient, in order to extract the albuminous substances, to let it lie for some 
time, frequently moving the pieces, in a vitriolic solution of 1 to 2 per cent. 
Thicker wood must be treated with the heated solution in wooden or sfone ves- 
sels, (since metal ones would be attacked by the metallic salt,) or be impreg- 
nated in the manner precribed by Boucherie. Konig thinks that when some- 
times the experiment does not lead to the desired result, the failure is at- 
tributable to the mere steeping of the wood without allowing time for lixivia- 
tion, and the consequent discharge of unfavorable elements, which is the indis- 
pensable condition of success. 
The preparation with copper-vitriol has been attended with satisfactory 
results in the case of several German railroads. In May, 1849, a commission 
of Prussian engineers examined the pine wood cross-ties which had been laid 
on the Berlin and Stettin road in 1841 and 1842. Here the impregnated and 
unimpregnated pieces lay close together. ‘The latter were in general wholly 
decayed, while the former were in good preservation and still gave promise of 
long duration. . 
In England the chloride of zinc, which is much cheaper, has been proposed, 
and with highly favorable indications as regards the result. ‘This process has 
been iried on the Hanoverian railroads, and it was found that sills which had 
lain for six years in the ground'were still fresh and sound. Upon examination 
by Wohler, it was stated that the chloride of zinc had penetrated, as well in 
oak as beech wood, deep into the material. From external indications this 
would not appear to be the case, yet here deception should be guarded against. 
In the oak wood chiefly a dark tint had spread to the depth of 1 inch to 14, 
and it was thence concluded that the chloride of zinc had penetrated thus far; 
but this proceeded probably from a dark-colored deposit produced by the action 
of the tannin of the wood on the sides of the iron vessel. The mineral imparts, 
in general, no color to the wood, and chemical analysis remains the only means 
of determining its presence. 
The greatest quantity of zinc was found in the beech wood, and in this 
respect no difference appeared in that which had and that which had not been 
steamed. With the oak it was otherwise, that which had not been steamed 
_ showing a much smaller proportion of the metal. Still poorer in zine was the 
beech steeped in zinc-vitriol, and poorest the unsteamed oak treated in the 
same way. In the latter, therefore, steaming would seem indispensable, for 
only by a thorough penetration of the metallic solution can decay be perma- 
nently averted. 
Recently a solution of the oxide of zine in wood-vinegar has been proposed, 
and more lately still the chloride of manganese, which is produced in great 
quantity in the manufacture of chloride of lime, and as an incidental product is 
of little exchangeable value. The free acid is here saturated with lime or with ° 
oxide of zinc. 
In North America, wood, especially that intended for ship-building, is salted, 
as with us flesh and vegetables are cured for longer preservation. ‘This method 
can scarcely be recommended in our own practice, since, however calculated 
to prevent the so-called voz, the prices which we pay under a monopoly place 
the article beyond our reach, considering the quantity necessary to be used. It 
takes, for instance, for a brig of 6,000 cwt. burden, not less than 1,600 ewt. of 
common salt, and that is with us quite a capital. The salt might be replaced, 
indeed, by the mother-water of the salt-works, since great efficacy is attributed 
to the chloride of magnesium contained therein, which, in a chemical point of 
view, is very similar to the chloride of zinc. \ 
It seems highly probable from the experiments of Konig that all these solu- 
tions of different kinds of salts, as far as they have succeeded in practice, act 
like the vitriol of copper upon the albuminous substances of the wood, and in 
like manner extract them therefrom. 
