Part IV.] E. S. Pearson: Antiseptic Treatment of Timber . 83 
vacuum pumps, the necessary gauges and a melting tank, fitted with a 
steam coil. 
The question of the percentage of the moisture in the timber at the 
time of treatment being of vital importance, will be again referred to 
later on. 
The oil used for treating the sleepers was Green oil and Liquid Fuel 
or Earth oil , mixed in equal proportions, by weight. The grade of 
Earth oil used is known as “ wax drippings 55 and has a specific gravity 
of -846, containing a high percentage of wax and an initial boiling point 
of 190° C. The Green oil used had a specific gravity of 1-095 and an 
initial boiling point of 221°C. The mixture commenced to boil at 190°C. 
and had a specific gravity of *950. In one experiment Earth oil only 
was used. 
In each case the sleepers after being charged into the cylinder were 
subjected to live steam for a fixed period, followed by a vacuum of 
upwards of 22 inches on the column of mercury. The oil heated to about 
75°C., was then run into the cylinder by the vacuum suction, after 
which the pressure was applied, in the case of Dipterocarpus pilosus 
(Hollong), starting with the first charge at 100 lbs. per square inch, 
and dropping the pressure in each successive experiment until 20 lbs. 
per square inch was reached. In the case of Terminalia myriocapa 
(Hollock), which did not take up the oil so readily, the first charge of 
sleepers was subjected to lOOlbs. and the last to 200 lbs. pressure per 
square inch. In the last experiment with ° Hollong ’ metre-gauge 
sleepers, a final vacuum was applied for an hour, in order to suck out 
the excess oil absorbed by the sleepers. Bischofia javanica sleepers 
were also tested, and subjected to 2001bs. pressure though, even at this 
pressure, poor results were obtained. 
The cylinder being of very limited dimensions, it was only possible 
for the writer to treat relatively few sleepers so that, after having fixed 
the essential points, the rest of the sleepers destined to be supplied to 
the Eailways for this experiment were treated on the same lines by 
Messrs. The Assam Oil Co. 
The results of these experiments are tabulated below :— 
h 2 
[ 213 ] 
