Part IV.] R. S. Pearson: Antiseptic Treatment of Timber . 21 
note on this subject. It has been in use on the Continent and in parts 
of America for upwards of 50 years, but its drawback is that it leaches 
out of the timber and, if used in strong solutions, attacks the metals ; 
its great merit is that it is cheap. Green oil is a commercial name for a 
good grade of Coal-tar creosote , with high boiling points and a relatively 
low percentage of tar acids. Its cost in England is 4 \d. per gallon, 
naked, while it costs about 13 annas per gallon to land it anywhere in 
the centre of the Indian Peninsula. The treatment with two such 
solutions consists in first allowing the timber to absorb as much of the 
salt solution as possible, and then after the sleepers have dried thoroughly, 
in plunging them in the hot oil bath and permitting them to absorb a 
relatively small quantity of oil. This has the effect of forming a thin 
shell of oil-impregnated tissue on the outside, enclosing and preventing 
the salt from being washed out by moisture and at the same time prevent¬ 
ing the foot-rail from coming into direct contact with the salt. The 
process is cheap when compared with a moderately heavy impregnation 
of creosote oil only ; for, though the salt solution is allowed to penetrate 
to the centre of the timber it only costs 2 annas 6 pies to treat a B. G. 
sleeper, while the amount of oil the sleeper is allowed to absorb is only 
about 25 per cent, of the quantity necessary when treating with oil 
alone. 
(iv) SOLIGNUM AND RANGOON OIL 
The reason for selecting Solignum for trial was that records of its 
use in India for protecting timber, other than Railway sleepers, are 
decidedly encouraging, even when only small quantities of oil have been 
used. Solignum is, however, an expensive oil. With a view, therefore, 
of reducing the total cost and allowing more complete impregnation, it 
was decided to mix it with equal quantities of Rangoon oil , which is 
relatively cheap. 
6. Powellizing Experiments carried out in the Field. 
(i) Arrangements made to carry out the experiments and the 
NUMBER OF SLEEPERS TREATED. 
The arrangements made to carry out these experiments were that the 
Forest Department should supply the sleepers f.o.r., that the Railway 
Board should pay the cost of freight to and from the impregnating 
plant in Bombay and that the Powell Company should treat 1,000 sleepers 
free of cost, the cost of impregnating the remainder being borne by the 
Forest Department. 
t 151 ] 
