Part II.] Pearson: Antiseptic Treatment of Timber. 
37 
Chapter III. 
The Open Tank or Brush Method ot Treating Timber. 
(!) DISCUSSION AND DESCRIPTION OF THE PROCESS. 
General. 
The ever-increasing demand, together with the limited supply of 
first class timber, have gradually and steadily raised its price in most 
parts of the civilized world, until the high rates have prohibited its use 
for many purposes. Various proposals have from time to time been put 
forward to meet this difficulty in order to reduce the high price in the 
timber market, amongst which may be mentioned projects formulated 
as long ago as the first half of last century which aimed at prolonging 
the life of the timber by treating it with antiseptic solutions and thus, 
in a measure, checking the ever-increasing demand. 
The first development in this direction consisted in the treatment of 
timber by pneumatic or hydrostatic injection, processes which require 
large and costly plants, generally of a stationary nature. As the forests 
retreated before the ever-advancing needs of agriculture and manufac¬ 
turing industries and became split up into many blocks, the lead over 
which it became necessary to carry timber to the central markets in¬ 
creased, while the cost of moving the timber to these central places, at 
which large impregnating plants could be worked, became prohibitive 
Again, as the value of the antiseptic treatment of timber became 
more fully recognised by landholders, firms and companies who often 
had occasion to treat small quantities of timber only, but the scope of 
whose work was not sufficient to justify the erection of an expensive 
plant, it was found necessary to devise cheap and more ready methods to 
meet their requirements. 
Though the Open Tank method was in vogue early in the middle c£ 
last century, it was not until the seventies that much attention was paid 
to it, though the process of immersion of timber in corrosive sublimate 
no doubt dates from an earlier period. Since then much progress has 
been made in this direction and many patent antiseptic solutions, used 
in the Open Tank method, have appeared on the market. 
( HO ) 
