Part IV.] R. S. Pearson: Antiseptic Treatment of Timber. 49 
uniform than was the case with the conifer timber. The reason for 
these variations is that no two pieces of timber have the' same density 
or contain the same amount of moisture and resin. The presence of 
sap-wood is also a powerful factor governing absorption, though in this 
instance inapplicable, as the sleepers were all cut from heart-wood. 
That absorption is directly proportionate to the time of immersion 
is shown by the ‘ Kanyin 5 sleepers, which were immersed for 8 hours and 
took up 34 lbs. each, while those immersed for 24 hours took up an 
average of 8-1 lbs. Heating the solution also has a striking effect on 
absorption: twenty-two sleepers were immersed for 24 hours in a cold 
solution and only took up 3-3 lbs. each, whereas a batch put into a solu¬ 
tion raised to 80°C. for 1 hour and then quickly transferred to a cold 
bath for 23 hours absorbed 6*8 lbs. each. The reason for this is obvious 
and is the basis on which certain timbers can be treated by the Open 
Tank method, i.e., that by placing the timber in a hot solution, the air 
in the timber expands and is driven out and as the wood also expands 
a small quantity of moisture is also expelled. As the whole cools down, 
the timber being immersed, instead of again absorbing air, absorbs the 
solution in which it finds itself. The actual period of heating does not 
exercise so great an influence on the absorption as the amount of drop 
in temperature after heating. 
After the sleepers had had time to dry thoroughly, they were again 
immersed—this time in a bath of Green oil heated to 50°C. for 5 minutes— 
during which time each sleeper absorbed 14 lb. of oil, thus completing 
the treatment according to this process. 
(c) Treatment of Terminalia tomentosa broad gauge sleepers with Chloride 
of Zinc and Avenarius Carbolineum oil. 
The sleepers with which this experiment was carried out were pre¬ 
pared in the Betul District, Berar Circle, Central Provinces, and were 
treated by the writer in March 1913, in a locally prepared tank, similar 
to that used at Jagadhri on the North-Western Railway. The 300 broad 
gauge sleepers to be treated were prepared from trees felled in December 
1912 and converted in January and February 1913 and were therefore 
not thoroughly seasoned. This was unavoidable though to be regretted ; 
while, owing to the fact that this species does not attain a large size in th e 
locality, the sleepers contained a large percentage of sap-wood and were 
not, taking them altogether, of a very high class. The fact that these 
sleepers contained sap-wood, is not a drawback, as the sap-wood is 
hard and, if properly impregnated, is probably as durable as the heart- 
wood. 
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