JACK PINE. ae 
seasoning unless care is exercised. It is more resinous than white 
pine, but less so than the yellow pines of the South. The heartwood 
is fairly durable in contact with the ground, but the sapwood rots 
quickly. 
A comparison of the mechanical properties of jack pine and other 
species is shown in full in Bulletin 556, United States Department of 
Agriculture. That bulletin gives the results of tests which show 
lower average values for jack pine than for Norway pine in cross 
bending, stiffness, and work to the maximum load perpendicular to 
the grain, and higher values in compression parallel and perpendic- 
ular to the grain, in hardness, and in shearing strength. The differ- 
ences, however, are not great. As compared with white pine, jack 
pine shows somewhat higher average values in all the above proper- 
ties except in stiffness and in cross bending, in which white pine 
averages slightly higher. 
The specific gravity of oven-dry jack pine wood, based on -volume 
when green, is 0.39, which is intermediate between Norway at 0.44 
and white pine at 0.36. The weight of a cubic foot of air-dried wood 
of jack pine is 29 pounds, that of Norway is 34, and that of white 
pine is 27 pounds. 
The structure of jack pine wood, in gross and microscopic charac- 
teristics, is not conspicuously different from that of other hard pines. 
UTILIZATION. 
Jack pine is used for railway ties, lumber, slack cooperage, pulp- 
wood, mine timbers, poles, fencing, and fuel. (Gee Pls. XI and 
XIT.) 
RAILWAY TIES. 
The greatest consumption of jack pine for railroad ties is in Canada, 
where in 1911 jack pine ? replaced cedar as the leading species used, 
and 54 million jack pine ties (88 per cent of all ties purchased) were 
bought by consumers at an average price of 41 cents. In 1914, 
8,379,064 jack pine ties, comprising 43.2 per cent of all ties bought, 
were purchased in Canada at an average price of 43 cents. In the 
Lake States jack pine is used much less for ties than for lumber. 
Ties can not be produced from trees under 10 inches in diameter 
breast high. Therefore, the proportion of the total stand of jack 
pine from which ties can be cut is relatively small and only the older 
trees can be used. Table 28 (appendix) indicates the number of ties 
it is possible to cut from trees of different sizes, and Table 9 shows the 
number of trees 10 inches and over in diameter in fully stocked stands 
of different ages. 
1“Mechanical Properties of Woods Grown in the United States,’”’ by J. A. Newlin and Thomas R. C, 
Wilson, of the Forest Products Laboratory. 
2 Including some lodgepole pine (P. contorta) from Alberta and British Columbia. 
