96 
Indian Forest Records. [Vol. VI 
Only 8 per cent, by volume of tar acids to be soluble in caustic 
soda solution. 
No distillate below 200°C., not over 5 per cent, below 210°C., 
not over 25 per cent, below 235°C., and the residue 
355°C., if it exceeds 5 per cent, in quantity, should be 
soft. 
The inspection of the timber and of the creosoting operations 
was carried out by the Provincial Forest Branch. The 
sleepers were cut from sound Douglas Fir logs felled within 
the preceding twelve months. No sleepers with shakes, 
splits, loose or large knots sap-wood or defective wood 
were passed for treatment. 
“ The sleepers were creosoted immediately after being sawn. 
English oil was used, the specific gravity at 38°C. being 1-04, 
13 per cent, by volume of tar acids extracted at 38°C., no 
distillate at 200°C., 1*2 per cent, at 210°C., 11*2 per cent, 
at 235°C., and a soft residue comprising 22 per cent, of the 
total volume remaining at 355°C. 
ut The sleepers were treated under a pressure process, remaining 
under pressure for six hours at a temperature of 125°F. 
and a pressure of 5 lbs. at the beginning of this period, 
and 180°F. and 85 lbs. at the end of the period. The sleep¬ 
ers were under treatment 30 hours, and in the creosote 
bath 24 hours. 
The average absorption of creosote per cubic foot was 12-03 lbs. 
The penetration of oil at the centre of the sleepers averaged 
over one inch in depth. The penetration from the end of 
the sleeper parallel to the grain was very much greater. 
The specification did not call for the boring of sleepers for spikes 
before treatment. The spike holes would greatly increase 
the penetration of creosote under the rail and strengthen 
the sleeper against decay at the weakest point, the rail- 
seat. Should any further trials be made of creosoted 
Douglas Fir sleepers, a point should be made of boring 
the sleepers before treatment. 
Constant improvements are being made in the method of creosot¬ 
ing Douglas Fir. A study of the service rendered by this 
shipment may indicate further changes to be made in 
the process of treatment, the quantity of oil used or the 
grade of wood to be accepted for treatment. A supply of 
cheap structural timber stands in British Columbia await¬ 
ing markets. We know that it can be given a preservative 
[ 226 ] 
