Part II.] Pearson: Antiseptic Treatment of Timber. 33 
cell being filled with the antiseptic solution, only those portions of 
the timber are impregnated which are liable to decay, namely, the 
tissue of the wood. 
It is claimed that the compressed air in the cells, on the pressure 
being taken off, drives any surplus fluid out of the timber, only leaving 
the amount required to saturate and fill the cell-walls. It is also stated 
that the oozing out of the superfluous solution can be further increased 
by forming a vacuum in the cylinder before the treated timber is i e- 
moved. 
Amount of Absorption and Cost. 
By this process the absorption can be reduced to 40 kilos, per cubic 
metre or 2*2 lbs. per cubic foot as compared with anything between 5 
to 20 lbs. per cubic foot absorbed when timber is treated by the common 
Creosoting method, and still the saturation of the tissue itself is said to 
be complete. Taking the absorption at 2*2 lbs. per cubic foot as stated 
above and the cost of processing at 1 a % Qp. per B. G. sleeper, the cost of 
treating a sleeper works out at 6 a. 2/>. 
Summary. 
It is too early to predict what will be the ultimate effect on the pie- 
servation of timber by this process. The system has much in its favour. 
in that it is cheaper than the old Creosoting process; on the other hand, 
only time can prove if the timber so treated will be lasting or not. It 
appears to have this advantage, when considering our Indian hardwoods, 
that the pressure has necessarily to be high so as to force the solution 
into the timber, a condition that is very likely in any case to be necessary 
with such species as TerminaUa tomentosa , Dipterocarpus tuberculatus 
or Lagerstrosmia tomentosa, all of which yield fairly hard-woods. 
( 7 ) CRESOL-CALCIUM PROCESS. 
Process and Theory. 
A recent process has been brought out by Mr. Felix Friedemann 
and Mr. Gustaf von Heidenstam in which they mix Cresol and milk of 
lime together, and impregnate the timber by any of the usual pneumatic 
methods. 
The theory of this process is based on the assumption that only about 
6 oz. of Creosote are necessarv to protect a sleeper of 3 cubic feet, but 
( 106 ) 
