[Part IV.] E. S. Pearson: Antiseptic Treatment of Timber. 103 
(ii) Seasoning of sleeper woods. 
(a) General discussion of the subject. 
It is difficult to lay sufficient stress on the importance of seasoning 
timber before treatment, for unless proper care is taken in this respect 
.any undertaking of this nature will be doomed to failure. In making the 
.above very definite statement, such processes as Haskinizing must be 
■excluded as, in this process, the saps in the timber are sterilized 
.and made use of for preserving the fibre. The reasons for only using 
seasoned timber for treatment are that (i) the inclusion of large quantities 
of moisture in the timber, by partial impregnation of the fibre, results 
in the premature decay of the tissue ; (ii) the smaller the amount of sap 
and nutritious substances left in the timber, the less liable is it to fungus 
and insect attack ; (in) the impregnation of the timber with an antiseptic 
in Open Tanks and to a somewhat less extsnt when treated under Pres¬ 
sure, becomes in direct proportion more difficult as the percentage of 
moisture in the timber increases ; (iv) unseasoned timber is liable to deve¬ 
lop cracks owing to the rapidity of seasoning when placed in the line ; 
this is a factor of paramount importance in the case of Indian timbers, 
exposed,to Indian conditions of climate ; and lastly, (v) that seasoned 
timber, even in an untreated state, lasts longer than unseasoned timber. 
The second point raised is a corollary of the first, and they both 
concern decay. For decay to take place in timber, moisture, air, light 
and warmth are necessary. Provided the timber does not crack, mois¬ 
ture and air are excluded from the outer surface of a sleeper by the shell 
■of treated tissue. As soon as a fine crack penetrates through the outside 
layer of treated timber, air and light are admitted and provided the 
internal layers of timber in the sleepers still contain much moisture, the 
•conditions necessary to fungus growth are present, hence the necessity 
for seasoning the timber before treatment. 
The third point refers to penetration of the antiseptic. That an oil 
■or salt will penetrate seasoned timber more readily than unseasoned 
timber is fairly obvious ; for, in the former state, the cells are more open 
than when filled with sap. In practice, if a piece of timber is treated 
green, on being cut open it will be seen that the distribution of the anti¬ 
septic oil is in streaks or patches and in any case is very irregular, due 
to the presence of moisture which has stopped peietration in places 
and not in others, whereas if the wood be seasoned the penetration is 
deeper and much more uniform. 
The next point refers to the liability of unseasoned timber to crack to a 
greater extent than does seasoned timber. This is a most important 
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