8 



BULLETIN 549, U. s. DEPARTMENT OP AGRICULTURE. 



were also treated a few miscellaneous ties, chiefly cypress, ash, syca- 

 more, locust, and hickory. 



Zinc chloride was the principal preservative used. Large quanti- 

 ties of creosote were also consumed in the treatment of ties. Zinc 

 chloride and creosote in combination treated 2,182,712 ties, of which 

 over 50 per cent were oak. The miscellaneous preservatives were 

 used principally for Douglas fir and tamarack. 



In treating ties with zinc chloride the average injection of the pre- 

 servative was 0.5 pound per cubic foot, while with creosote oil the 

 average quantity used was 8.5 pounds per cubic foot. 



The practice of treating wood has increased because of the eco- 

 nomic necessity of less frequent renewals of timber subject to decay. 

 Prior to 1900 the wood-preserving industry developed slowly, and 

 only during the last 10 or 15 years has it gained a permanent foot- 

 hold in the United States. From a total of 12 plants in 1900 the 

 industry has grown until at the present time there are 128 plants in 

 commercial operation. Of this number 95 are pressure plants, 27 

 are nonpressure plants, and 6 are equipped for both pressure and 

 nonpressure treatment. The industry in this country has been built 

 up largely on crossties and other railroad material. Of the total 

 quantity of 141,858,963 cubic feet of material of all kinds treated 

 with preservatives in 1915, a little more than 78 per cent was crossties. 



The number of ties treated each year, beginning with 1909, is 

 shown in Table 9, together with the quantity of ties reported pur- 

 chased. 



Table No. 9. — Number of crossties reported purchased and treated, by years. 



Year. 



Reported 



Reported 



purchased. 



treated. 



1909 



123,751,000 



20,693,013 



1910 



148,231,000 



26, 155, 077 



1911 



135,053,000 



28,394,140 



1912 



(') 



32,394,336 



1913 



0) 



40, 260, 416 



1914 



0) 



43, 846, 987 



1915 



97, 106, 651 



37, 085, 585 



1 Statistics for these years not obtained. 



ADDITIONAL COPIES 



OF THIS PUBLICATION MAY BE PROCURED FROM 



THE SUPERINTENDENT OF DOCUMENTS 



GOVERNMENT PRINTING OFFICE 



WASHINGTON, D. C. 



AT 



5 CENTS PER COPY 

 A 



