Part IV.] B. S. Pearson: Antiseptic Treatment of Timber. 57 
(-y) General conclusions based on the results of experiments 
with sleepers treated with Chloride of Zinc and either Green 
oil or Avenarius Carbolineum. 
The primary object of these experiments was to compare the value 
of a mixed impregnation with the standard method of creosoting, by 
which some 8 lbs. per cubic foot of a good grade Coal-tar creosote are 
introduced into the timber, otherwise known as the “ Fuel Cell ” or 
“ Straight method 55 of impregnation. When comparing the relative 
merits of the two processes, the most important factors to be considered 
are ( i ) durability and (ii) cost. With respect to these experiments, the 
durability of the timber cannot be determined for some years, while the 
cost has been fixed. Broad gauge Pine sleepers cost Be. 1-1-4, metre- 
gauge Dipterocarp sleepers cost Be. 0-6-0, and broad gauge Terminalia 
tomentosa sleepers Be. 1-0-0 to treat. *A11 creosote has to be imported 
into India, and costs somewhat about 12 annas per gallon, to land at 
any of the experimental stations ; based on this figure, the estimated 
cost of treating a broad gauge sleeper by the “Full Cell ” process is 
estimated at Bs. 2-4-0, or double the cost incurred when treating broad 
gauge sleepers by a mixed impregnation process with a salt and oil. 
Provided the durability tests with sleepers treated by a mixed impregna¬ 
tion method come up to expectation, it may prove to be one of those 
suitable for treating sleepers under Indian conditions. 
9. Field Experiments carried out with Solignurn and Burma oil 
or Liquid Fuel. 
(i) Arrangements made to carry out the experiments and the 
NUMBER OF SLEEPERS TREATED. 
The fourth and last group of experiments to be carried out, according 
to the original scheme laid down for this enquiry, consisted in treating 
the five species of timber selected with a mixture of Solignum and Earth 
oil, the former a derivative of Coal-tar creosote and the latter of petroleum 
oil. Solignum is an expensive oil, though of established value for treating 
timber ; a crude petroleum oil was added to it to cheapen the mixture, 
and thus permit a greater quantity of the solution being introduced 
into the timber. 
The arrangements made to procure the sleepers, and the localities 
whence they were supplied were the same as those recorded in the previous 
experiments. 
The Pine and Terminalia tomentosa sleepers were treated by the 
writer, and the Dipterocarp sleepers by Babu Gyan Singh, the 
writer’s assistant. 
* Note. —Since this was written there is every prospect of Coal-tar Creosote being avail¬ 
able in the near future in India. 
[ 187 ] 
