294 



FOREST PRODUCTS 



absorption of from 6 to 10 Ib. of oil is retained per cubic foot of wood. 

 When zinc chloride is used, the same general process is followed except 



$.80 

 $.70 



$.GO 



-?.50 



$,40 



White Oak 



Red 



Oak 



1902 



1904 



1906 



1908 



1910 



1912 



1914 



1916 1918 



FIG. 79. Graphic representation of the price levels of No. i white and red oak cross ties 

 delivered f.o.b. cars at East St. Louis for the years 1902 to 1917, inclusive. All ties 

 were 6"X8"X8'. 



that a different preservative is used. Many variations of both the 

 creosote and zinc chloride forms of treatment are used. 



NUMBER OF CROSS TIES TREATED BY PRESERVING PLANTS DURING 1915, 

 BY KINDS OF PRESERVATIVES AND KINDS OF WOOD 



Proceedings. American Wood Preservers' Association. 

 * Includes lodgepole pine and western yellow pine. 3 Includes western larch. 



THE PROTECTION OF TIES AGAINST MECHANICAL WEAR 



Railway engineers estimate that between 10 per cent and 75 per cent 

 of all untreated ties that are unprotected by means of tie plates fail and 

 must be renewed because of severe mechanical abrasion. This is espe- 



