674- ANTISKPTIC TREATMENT OF TIMBER. 



In comparing the durability of injected and uninjccted 

 railway-sleepers it may be stated that on the average : — 



Beech durability trebled. 



Scotch pine ,, doubled. 



Oak „ 



Spruce „ increased 50% 



According to Burescli, beech railway-sleepers injected with 

 chloride of zinc last only 8 or 9 years, but their life is reckoned 

 at 18 years on the Koln-Minden railway, whilst a thoroughly 

 injected beech-sleeper costs only half the price of an oak-sleeper. 

 It is clearly proved by experience on many railway lines and 

 by numerous carefully conducted experiments that injected 

 beech railway- sleepers are quite durable enough to be extensively 

 used, yet only 1% of the sleepers used on German lines and 

 3 % in Austria-Hungary are of beech. This non-use of beech is 

 therefore unjustifiable, and the different State Forest Depart- 

 ments should therefore endeavour to supply large quantities 

 of beech sleepers from sound young trees, whilst the railways 

 should use them only after thorough injection by steaming and 

 when they are air-dry. 



It appears that when chloride of zinc is used, the injected 

 sleepers are more durable if laid down a few months after injec- 

 tion and not fresh from the injecting works. 



The cost of injection varies according to the method employed. 

 Buresch has given figures for a number of German lines on 

 p. 82 of his valuable book already referred to, being as follows 

 per cubic foot : — 



d. 



Chloride of zinc (steam-pressure) 2'04 



Sulphate of copper (Boucherie) 2*!28 



Kyanising 8*72 



Kreosoting 4'92 



In Germany the cost of injection per railway-sleeper is given 

 as follows by Nepomacky : — 



Oak. Scotch pine^ 



d. d. 



Sulphate of copper (Boucherie) 4*1 5*2 



C'hlorido of zinc (steam pressure) 8*3 10*3 



Corrosive sublimate ()*G 11-6 



Creosoting 14-8 24*2 



