50 
Indian Forest Records. 
[Vol. VI 
The object aimed at vas to impregnate the sleepers with from 9 to 
12 lbs. of a 2 per cent, solution of Chloride of Zinc and to coat them with 
Aunarius Carholinenm oil, having given them time to dry after immersion 
in the salt solution, the oil treatment being carried out to fix the salt 
and to preserve the timber. 
To ascertain the necessary period of immersion required in order to 
make the sleepers absorb 12 lbs. of the Chloride of Zinc solution, a certain 
number of sleepers were weighed before and after treatment, with the 
following results :— 
TABLE XV. 
Species. 
Average absorp¬ 
tion, per sleeper, 
of 15 sleepers. 
Temperature of 
Chloride of Zinc 
solution. 
Period of immersion. 
Terminalia tomentosa. 
lbs. 
11-4 
75°C. 
3 hours heating and 18£ 
hours cooling = 21£ hours. 
i 
Ditto 
8-5 
60°C. 
. 
3 hours heating and 21 hours 
cooling = 24 hours. 
Ditto 
12-26 
79°C. 
5 hours heating and 19 hours 
cooling = 24 hours. 
Ditto 
13-46 
80°C. 
Ditto 
After having ascertained that it took 5 hours heating to 80°C. and 19 
hours cooling, or 24 hours in all, to make the sleepers take up 12 lbs. each, 
the rest of the sleepers were treated on the same lines. 
It was, in a way, gratifying to have found it possible to make so 
hard a wood as that of Terminalia tomentosa take up the required amount 
in 24 hours, as some difficulty was anticipated in doing so when working 
with open tanks. 
In order to ascertain the time required for the sleepers to regain 
their natural weight, after having been treated in the salt solution, a 
number were weighed directly after being withdrawn from the treating 
tank and again seven days later. The total weight of 15 sleepers was 
3,381 lbs. before immersion, 3,551 lbs. after immersion and 3,384 lbs. 
seven days later. The sleepers had, therefore, practically regained 
their normal weight within 7 days ; in fact, some were actually lighter 
than before immersion though, as some were over weight at that time, 
they were all allowed to dry for a further period of seven days to ensure 
complete dryness before subjecting them to an oil bath. 
[ 180 ] 
