86 
Indian Forest Records. 
[Vol. VI 
The conclusions arrived at from these experiments may be sum¬ 
marized as follows :— 
(a) That Dipterocarpus pilosus , or ‘ Hollong ’ timber treats with great 
ease when immersed in oil and subjected to pressure. With 
a 100 lbs. pressure kept up for an hour (Experiment I), metre- 
gauge sleepers each took up 19*56 lbs. of oil, which is con¬ 
siderably more than is necessary. When subjected to 20 lbs. 
pressure for 15 minutes (Experiment V), the sleepers took up 
11*2 lbs. each. The oil penetrated to the centre of the sleepers 
under 100 lbs. pressure and very nearly so when subjected 
to 20 lbs. pressure. Looking to the nature of the timber, 
which is very straight-grained with large pores and to the 
climatic conditions prevailing in Assam and parts of Bengal, 
where such treated sleepers are likely to be laid down, it 
would be advisable to treat them with anything from 9 to 12 
lbs. of oil per metre-gauge sleeper or 6 lbs. to 8 lbs. per cubic 
foot. It is obvious that the oil will evaporate in direct pro¬ 
portion to the size of the pores and hence the necessity for 
more completely impregnating the whole tissue. To do so, 
it will be necessary to steam the sleepers for 10 minutes at a 
pressure of 10 lbs., to apply a vacuum of 10 inches for 10 
minutes, to run in the oil at from 75°C. to 80°C., and apply 
a pressure of from 20 to 25 lbs. per square inch for 15 
minutes, according to the degree of the seasoning. 
(6) That Terminalia myriocarpa , or ‘ Hollock 5 requires more drastic 
treatment than ‘ Hollong,’ owing to the fact that the timber 
is denser and harder and contains fewer pores, generally set 
obliquely one to the other as is characteristic of the timber of 
most Terminalias. In the experiments carried out with 
‘ Hollock,’ the absorption amounted to 5’3 lbs. with a pressure 
of 100 lbs. applied for one hour (Experiment No. VIII) and 
8*6 lbs. per sleeper with a pressure of 200 lbs. for two hours 
(Experiment No. X). Probably, by increasing the time during 
which the pressure is applied from 2 hours to 4 hours, the 
impregnation could be increased to about 10 lbs. per metre- 
gauge sleeper while, looking to the good quality of this timber, 
not more than 10 lbs. per metre-gauge sleeper is considered 
necessary. To obtain this absorption, steaming should be 
carried out for one hour at 20 lbs. pressure, followed by a 
vacuum of 20 inches for one hour, the oil run in at 75°C. and 
the pressure kept at between 175 lbs. and 200 lbs., according 
to the degree of seasoning of timber. As an alternative to 
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