Part IV.] It. S. Pearson: Antiseptic Treatment of Timber. 51 
The sleepers were then treated in a hot bath of Avenarius Caibolineum 
oil, selected batches of which gave the following results :— 
TABLE XVI. 
Species. 
Average absorp¬ 
tion, per sleeper, 
of 3 sleepers. 
Temperature of 
Avenarius Car- 
bolineum oil. 
Period of immersion. 
Terminalia tomentosa 
lbs. 
2-8 
52°C. 
10 minutes. 
Ditto 
3-8 
54°C. 
8 „ 
Ditto 
2-8 
62°C. 
5 „ 
Ditto 
3-8 
46°C. 
5 „ 
Ditto 
2-8 
50°C. 
3 „ 
Ditto 
3-6 
55°C. 
2 
Ditto 
2-5 
38°C. 
Simply dipped in and taken 
Ditto 
3-3 
40°C. 
out again. 
Ditto 
Ditto 
2-6 
40° C. 
Ditto 
It is clear from the above figures that the result of either dipping 
in the sleepers and pulling them out again at once or immersing them 
for upwards of 10 minutes, when dealing with a close-grained timber 
such as Terminalia tomentosa , gives the same results. 
This is as might be expected, as the oil in any case could only affect 
the outer edge of the tissue and fill up the small cracks, not having time 
to sink deep into the tissue itself. It remains to be seen whether so 
slight an impregnation of oil will be sufficient to prevent the Chloride 
of Zinc from being leached out of the timber. 
Before leaving this group of experiments, it is necessary to record a 
point of some interest in connection with the rate of absorption of the 
oil. It was found that, when treating the Terminalia and Dipterocarp 
sleepers, the oil was absorbed by the timber much more readily when 
the sleepers had been originally treated in Chloride of Zinc for 24 hours 
than when no such previous treatment had taken place. The reason 
for this is no doubt that as the timber had been subjected to a water 
bath and also a good deal of the sap had been expelled by expansion of 
the timber due to heating, the surface of the wood and the outer inter¬ 
cellular spaces were clean ; in other words, the outer tissue being porous 
it was in the best possible state to take up the solution. It follows, 
therefore, that if difficulty is found in making a dense timber absorb 
sufficient antiseptic, it should either be immersed in a hot bath oyplaced 
in a running stream of water for two or three weeks, and then allowed 
to dry thoroughly before treatment. 
[ m ] 
F 2 
