18 
Indian Forest Records. 
[Yol. YI 
The figures speak for themselves : the specimens treated with Coal- 
tar creosote products have lasted on an average four years and eight 
months and those treated with salts three years and eight and a half 
months, out of a possible five years. It may, therefore, be stated with 
safety that creosote products are preferable to salt solutions for 
treating timber for use in India. It is just possible that salt solutions 
might answer in the very dry localities, such as in Sind and parts of the 
Punjab, though that point still remains to be proved. 
The value of each oil or salt or combination of salt and oil has been 
dealt with after recording the result of each individual experiment, so 
need not be repeated here ; suffice it to say, that the final selection of 
any given antiseptic which has given satisfactory results, must be decided 
on its cost and the amount of the substance necessary to preserve the 
timber for a stated period. These points will come under general dis¬ 
cussion in Part VI. 
PART III. 
RESULTS OF FIELD EXPERIMENTS, TIMBER TREATED BY 
THE OPEN TANK PROCESS. 
1. Object of the Experiments. 
The laboratory experiments, the results of which have already been 
recorded, were carried out with the object of ascertaining the value of 
certain antiseptics, the durability of any given species after treatment 
being of secondary consideration. The Field Experiments, on the other 
hand, were carried out with the primary object of ascertaining the dur¬ 
ability of certain timbers after treatment, when used as railway sleepers. 
Further, by dealing with a fairly large number of sleepers, it was possible 
to ascertain certain other factors, namely, (^') the approximate cost of 
felling, extraction and conversion of the various species, (ii) the approxi¬ 
mate cost of treatment with different antiseptics, and (Hi) to determine 
the period of immersion required in order to make the sleepers take up 
the required amount of antiseptic solution. 
2 . Scope of the Experiments. 
(i) Number of sleepers treated. 
Th e original scheme, according to which the field experiments were 
to be carried out, contemplated the treatment of 20,000 sleepers made 
up of five different species, 1,000 of each to be treated every year, and 
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