74 
Indian Forest Records. 
[Vol. VI 
heart-wood and 6 hours’ immersion for sap and heart- 
wood sleepers is sufficient to make them take up 
15 lbs. each. 
(iv) It is not only useless but wrong to treat sleepers recently 
taken out of the floating stream, even if they are 
thoroughly seasoned, before being thrown into the stream 
for floating purposes. The minimum period for seasoning, 
after the sleepers have been removed from the floating 
stream, „is 4 months in the cold weather and 3 months 
in the hot weather. 
(v) The main factors regulating the rate of absorption of oil by any 
one species of timber are : (i) the percentage of moisture 
in the timber, at the time of treatment, (ii) the 
difference in the maximum and minimum temperature 
of the oil during treatment ; the greater the difference, 
the greater the rate of absorption and quantity of oil 
taken up, (in) the percentage of sap to heart-wood, and 
(iv) structure. 
( it ) Treatment of Assam species of timber in Open Tanks. 
In 1912, when the writer was on tour in Assam, the question of supply¬ 
ing the Assam-Bengal Railway with treated sleepers came under dis¬ 
cussion, and proposals were ma^e to carry out experiments with a species 
of timber known as Cynometra polyandra ; later, the scope of scheme 
was further extended by Mr. Perree, the then Conservator of Forests 
of the Eastern Circle, by the addition of other species of timber. Under 
his directions, an experimental Open Tank plant was erected at Jaipur 
by Mr. Cooper, the Divisional Forest Officer of the Lakhimpur Divi¬ 
sion, and the sleepers for the experiment prepared and seasoned. In 
February 1915, Messrs. Perree and Cooper, in company with the 
writer, proceeded to Jaipur to carry out these experiments. 
The species of timber selected for testing were (i) Artocarpus Chap - 
lasha ‘ Cham,’ (ii) Dipterocarpus pilosus ‘ Hollong,’ (Hi) Altingia excelsa 
‘ Jutuli,’ (iv) Cynometra polyandra ‘ Ping ’, (v) Terminalia myriocarpa 
‘ Hollock 5 and (vi) Terminalia belerica ‘ Bhumra.’ 
The timber was allowed to season in the log and was then cut into 
metre-gauge sleepers and allowed further to season under cover for from 
8 months to 2 years. The timber was, therefore, thoroughly dry, while 
the absence of cracks was very noticeable, an important point demon¬ 
strating the great value of slow and thorough seasoning. 
The solution used to treat the sleepers was Green oil and crude Earth 
or Petroleum oil, mixed in equal quantities by weight. 
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