29 
Part II.] Pearson : Antiseptic Treatment of Timber. 
with the heavier oils of Creosote and also mixed with sodium-fluoride. 
Even unmixed its action as a timber preservative is undeniably good 
and though not now used pure to the extent it was formerly, it still 
finds a place as one of the . foremost salt antiseptics both in Europe and 
America. Mr. Sherfesee of the United States Forest Department states 
that — “ In the United States the tendency in wood preservation is to 
modify the processes rather than to change the preservatives. At 
present, Creosote and zinc chloride pure or in mixture, are the only pre¬ 
servatives which are in general use." The Hauptmann Malenkovic 
does not favour zinc-chloride alone but recommends zinc-chloride mixed 
with equal proportions of sodium-fluoride, either injected under 
pressure or employed in the Open Tank method. In the former case the 
period of treatment is of short duration, while in the latter case immer¬ 
sion for 8 days is necessary in a more concentrated solution of the 
mixture. 
From what has been said above it will be seen that chloride of zinc 
has still many supporters, who either advocate its use pure or when 
mixed with other substances. Another factor in favour of this process 
is that the salt has been in use for many years as an antiseptic and con¬ 
sequently has been given extensive trials overlong periods of time and 
still remains in favour. 
Cost of Impregnation with Chloride of Zinc. 
The cost of this process must depend entirely on the strength of the 
solution used and the amount of absorption by various classes of timber 
and further on to the method of treatment adopted, be it by injection or 
by immersion only. The price of chloride of zinc of commerce is B20 
per cwt. in Calcutta (solid), so that with a solution of 1 in 50, and 
taking the absorption as 3 lbs., lbs. and 10 lbs. per cubic foot respec¬ 
tively, according to the density of the timber to be treated and the cost 
of labour, etc., at BO-1-6 per sleeper, the cost of treating a B. G. 
sleeper according to the amount absorbed, would be B0-2-0, BO-2-8 
and BO-3-5; in other words, this is an extremely cheap method of 
treating timber. 
Dr. Warth, in his report, puts the cost of impregnating oak at 
0*2^. and of beech at 0*4^. per cubic foot; which for treating a B. G. 
sleeper of oak works out at OMd. and of beech at 1*32^., or adding 
1 5 d. to each as cost of processing, the cost of treating oak sleepers comes 
to 2T 6d. and of beech sleepers to 2'82^.— prices very similar to those 
worked out for India. 
( 102 ) 
