48 BULLETIN 1485, U. S. DEPARTMENT OF AGRICULTURE 
United States and in the mountains to southern Kentucky, to northern Ohio, 
Indiana and Illinois, eastern and central Iowa and northern Missouri. 
Oven-dry weight per cubic foot, green volume. — 23 pounds. 
Fiber length. — 1 mm. 
By Sulphite Process 
Reduces readily. 
Unbleached pulp: Of' excellent color; usually contains small black specks, 
which, however, disappear on bleaching: easily bleached. 
Yields: 45 to 50 per cent. 
Bleach required: 10 to 15 per cent. 
By Soda Process 
Reduces fairly readily. 
Unbleached pulp: Bleaches easily. 
Yields: 45 to 50 per cent. 
Bleach required: 10 to 15 per cent. 7 
By Mechanical Process 
Aspen is readily reduced to mechanical pulp, yielding 85 to 86 per cent of 
standard strength with approximately three times as much power as is required 
for spruce. Upon the introduction of the ground-wood process aspen came to 
be used to a considerable extent on account of the light color of the pulp. Spruce 
has now supplanted it because much less power is required and pulp of greater 
strength and better felting properties is obtained. 
Balsam Poplar (Populus balsamifera) 
Other names in use. — Balsam, balm of Gilead, Cottonwood, and faca mahac. 
Range. — Coast of Alaska and valley of Mackenzie River to Hudson Bay and 
Labrador; southward to northern New England and New York, central Michi- 
gan and Minnesota, northern North Dakota, western South Dakota, northwest- 
ern Nebraska, Colorado, northern Montana, Idaho, Oregon, and Nevada. 
Oven-dry weight per cubic foot, green volume. — 26 pounds. 
Fiber length. — 1 mm. 
By Sulphite Process 
Reduces with exceptional ease. 
Unbleached pulp: Of excellent color; not contaminated with black specks 
characteristic of aspen; very easily bleached. 
Yields: 45 to 50 per cent. 
Bleach required : 5 to 10 per cent. 
By Soda Process 
Reduces readily. 
Unbleached pulp: Fairly easily bleached. 
Yields: 45 to 50 per cent. 
Bleach required: 15 to 20 per cent. 
By Mechanical Process 
Behavior probably similar to that of aspen. 
Cottonwood 
Other names in use.- — For the purposes of this bulletin both eastern cotton- 
wood (Populus deltoides) and southern cotton wood (P. deltoides virginiana) are 
included under the name "cotton wood." 
Range. — The range of eastern cottonwood is commonly recognized as north- 
western Vermont, through western New York, eastern border of Pennsylvania, 
and central Maryland; central-eastern Mississippi. The complete range is 
imperfectly known. Southern cottonwood ranges from Quebec and Lake Cham- 
plain southward through western New- England to Florida; westward to southern 
Minnesota, the Dakotas, eastern Nebraska, Kansas, Oklahoma, and Texas. 
Oven-dry weight per cubic foot, green volume. — 23 pounds. 
Fiber length. — 1.3 mm. 
7 About 7 to 12 per cent when cooked by sulphate process to yields indicated. 
