Part II.] Pearson : Antiseptic Treatment of Timber. 4S 
Description of the Process. 
The process is a simple one, the timber is immersed for 10 to 15 
days in a weak solution of 1 in 100 to 1 in 150, the tanks into which the 
solution is run being generally made of wood as the sublimate corrodes 
iron. 
European and Indian Records. 
As stated above, the salt is used for impregnating telegraph poles m 
Germany and its action is undoubtedly beneficial, wjbile its use for 
poisoning seeds, museum wood and botanical specimens is well known. 
Dr. Warth states that it was used on the Baden and Rhein-Nahe 
Railways for impregnating sleepers as long ago as 1840, and that the 
results were most satisfactory, treated sleepers having a life of 20 years 
and upwards, but that afterwards the system of impregnating with 
chloride of zinc took its place, being a cheaper process. 
Chloride of mercury has been experimented with in India by the 
Great Indian Peninsula Railway, but only with very inferior species and 
not with the better class of “ auxiliary species ” of timber. The 
results were fairly satisfactory, in that the sleepers were in good condition 
after four years; however, the high cost of treating the sleepers caused 
the experiment to be discontinued. 
Cost of Treating. 
Dr. Warth states that corrosive sublimate is taken up by all 
woods alike at the rate of O'066 lbs. of the salt per cubic foot. He further 
states that the cost of processing is estimated at 0*5^. per cubic foot and 
the cost of the salt at 2*5 d. per cubic foot, and therefore 3d. per cubic 
foot for the whole process. This estimate is based on the assumption 
that the strength of the solution used is 0’66 per cent, of salt. It is not 
known on what grounds the statement is based that all timbers alike 
take up O’066 lbs. per cubic foot, as it appears likely that the soft 
species would take up more than heavy and close-grained woods. Assum¬ 
ing that this is correct and that the present price of corrosive sublimate 
( ) 
