Part IV.] E. S. Pearson: Antiseptic Treatment of Timber . 99* 
The most important alteration made to the former list consists in 
excluding Pinus excelsa from the first class, not because the timber is 
unsuitable, but on account of the demand for this timber for construc¬ 
tional purposes. Dipterocarpus pilosus, D. turbinatus, Shorea assamica y 
Terminalia myriocarpa , T. Manii and T. paniculata have been added 
to class I, partly on account of the supplies being considerable 
and also because recent tests have demonstrated the possibility of 
treating these timbers, while their mechanical strength is sufficient 
to withstand the wear and tear to which sleepers are subjected. 
The most noticeable additions to the first class are Abies Pindrow 
and Picea Morinda, the ‘ Silver fir ’ and ‘ Spruce,’ respectively, the 
supplies of which from the Punjab forests are very considerable. A 
point about which doubt might be expressed in classifying these two' 
timbers under list I, is in respect to their mechanical strength and resist¬ 
ance to absorb an antiseptic. In justification of such a classification, it 
may be said that in strength ‘ Spruce ’ equals, if it does not exceed, that 
of ‘ Douglas Fir,’ which, after treatment, is commonly used in Canada 
and America for sleepers, while 4 Silver fir ’ is little inferior to that species. 
As regards treatment, the tests carried out in England, which are corro¬ 
borated by laboratory tests in India, show these two species to be ex¬ 
tremely difficult to treat; on the other hand, ‘ Douglas Fir ’ is equally 
difficult to treat, so there seems little reason to doubt that the special 
process adopted in treating the latter species may answer equally well 
with ‘ Silver fir ’ and ‘ Spruce.’ 
Class II has lost some species at the expense of class I; on the other 
hand, Altingia excelsa , Anthocephalus Cadamba, Valeria indica, Terminalia 
bialata, Mesua ferrea and Dillenia indica have been added to it. 
Class III could, no doubt, be very much increased, consisting as it 
does, chiefly of timbers which might easily be placed in class I, were 
they either available in larger quantities or were not already in such 
demand for other purposes that their market value in some parts of India 
is already beyond that of sleeper woods. 
The above lists have been prepared after taking into consideration the 
most important factors upon which depends the possibility of using 
the timber, after treatment, for Eailway sleepers. The essentials are 
(1) that the available supply should be large, (2) that the cost of the 
timber as a suitable treating plant be not excessive, (3) that the timber 
be of sufficient strength for the purpose, and (4) that it should yield 
readily to treatment. 
It is not likely that all the timbers mentioned, or even those in class I, 
will come into use in the near future. It is, however, possible to indicate 
which of them are likely to receive prior attention, chiefly on account of 
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