Part IV.] R. S. Pearson: Antiseptic Treatment of Timber. 4-7 
The above figures denote considerable variations in absorption, due 
chiefly to the amount of sap-wood present in different sleepers and to the 
differences in density of the timber of individual sleepers. It was found 
that the average amount of the solution taken up by the Pinus longifolia 
sleepers was 16 lbs. and that of the Pinus excelsa sleepers to be 14 lbs. 
which, together with the oil treatment, is considered sufficient to protect- 
the timber. 
The sleepers, after treatment in the salt, were allowed about a fort¬ 
night in which to dry, this period being considered sufficient, as at the 
time of treatment the temperature at Jagadhri stood well over 110°F. 
in the day, while the hot winds materially hastened the process of drying. 
The oil bath, to which the sleepers were then subjected, was limited to 
a 3 to 5 minutes immersion, during which period the Pinus longifolia- 
sleepers absorbed 4*4 lbs. and the Pinus excelsa 3-5 lbs. of Green oil per 
sleeper. The object of the coating of oil given to the sleepers was 
primarily to prevent the salt from leaching out of the' timber by excessive 
moisture and also in a measure to preserve the timber. 
(6) Treatment of Dipterocarpus tuberculatus and D. alatus metre- 
gauge sleepers with Chloride of Zinc and Green oil and a few 
with Atlas solution and Green oil. 
The Dipterocarp metre-gauge sleepers were prepared from logs which 
had been seasoning for over a year, and were allowed to lie in the depot 
for a further period of 2 or 3 months after conversion and before being 
treated. 
The object aimed at in this set of experiments was to treat 700 metre- 
gauge sleepers with Chloride of Zinc and Green oil and 300 metre-gauge 
sleepers with Atlas and Green oil. Ihe latter process was given a trial, 
but was abandoned after 30 sleepers had been tfeated, as it was soon 
found that working in open tanks, with native labour, the business was 
too dangerous owing to the^high percentage of arsenic in the solution. 
The balance of the sleepers destined for this experiment were therefore 
treated with Chloride of Zinc and Green oil. 
A 2 per cent, solution of Chloride of Zinc was adoptee, and it was 
decided to try and make the sleepers take up 9 lbs. of the solution, that 
is, 6 lbs. per cubic foot. The sleepers after treatment in the salt, were 
allowed to dry thoroughly, a point of great importance and then immersed 
m Green oil 
To ascertain the necessary period of immersion in order to make the 
sleepers take up 9 lbs. of oil each, a number were weighed before, and 
[ 177 | 
