16 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
PHYSICAL PROPERTIES OF SULPHITE AND SODA PULPS MADE FROM 
SOUND AND FROM DECAYED WOOD 
CHARACTER OF WOOD USED 
Investigations were made at the Forest Products Laboratory to 
determine the effect of decay in wood on the yield and on the quality 
of chemical pulps made from it, and to ascertain the difficulties en- 
countered in manufacturing paper from such pulps. 
Through the courtesy of the cooperating mills, shipments of spruce, 
hemlock, and aspen woods representing sound wood and wood in 
various stages 01 decay were received. These woods may be de- 
scribed as follows: 
Sample 2545. Spruce wood from a Wisconsin mill; nearly free from decay; 
taken from the top of a pile approximately 35 feet high, containing about 10,000 
cords of 8-foot wood. Used for sulphite cook No. 7, pulp designated as No. 2547. 
Sample 2516. Spruce wood; considerably decayed ; taken from the bottom of 
the same pile from which No. 2545 was taken. Used for sulphite cook No. 6, 
pulp designated as No. 2548. 
Sample 2560. Spruce wood from a Wisconsin mill; nearly free from decay and 
in physical appearance similar to No. 2545. Used for sulphite cooks Nos. 8 and 
10, pulp designated 560A and 560, respectively, and for soda cook No. 6, pulp 
designated as No. 2559. 
Sample 251^1. Spruce wood from a Wisconsin mill; so badly decayed that it 
was rejected at the pulp mill. (See PI. IX, fig. 4.) Used for sulphite cook No. 9, 
pulp designated as No. 2555, and for soda cook No. 7, pulp designated as No. 
2557. 
Spruce wood y not numbered; presumably sound; received at the Forest 
Products Laboratory and cooked prior to these studies. Used for sulphite cook 
No. 336, pulp designated as No. 2540. 
Spruce wood, not numbered; presumably sound; received at the Forest 
Products Laboratory prior to these studies. Used for soda cook No. 109, pulp 
designated as No. 540. 
Sample 2552. Aspen wood selected at random from a Michigan mill pile; 
extent of decay not certain. Used for sulphite cook No. 1, pulp designated No. 
5521, and for soda cook No. 4, pulp designated as No. 552D. 
Aspen wood, not numbered; presumably sound; received at the Forest Prod- 
ucts Laboratory and cooked prior to these studies. Used for sulphite cook No. 
351, pulp designated as No. 50. 
Sample 2542. Hemlock wood from a Wisconsin mill; considerably decayed; 
used for sulphite cooks Nos. 2, 3, and 5, pulps designated respectively 542A, 542B, 
and 542C, and for soda cook No. 3, pulp designated as 542D. 
Sample 2554- Hemlock wood from the same mill from which No. 2542 was 
received; sound; used for sulphite cook No. 4, pulp designated as No. 554. 
Hemlock wood, not numbered; presumably sound ; received at the Forest 
Products Laboratory and cooked prior to these studies. Used for soda cook 
No. 228, pulp designated as No. 40. 
CHIPPING LOSSES 
On account of the breaking down of the fibers by the fungi, decayed 
wood is brash. In the chipping of such wood a considerable loss 
occurs in " sawdust" and shives which are rejected by the screens. 
Trial chipping and screening of sound and decayed spruce wood from 
the lot under investigation gave the foUowing screening losses in 
per cent by weight: 
Per cent loss 
Sound 4. 4 
Relatively sound (No. 2545) 5. 6 
Somewhat decayed (No. 2560) 13. 2 
Considerably decayed (No. 2546) 15. 6 
Badly decayed (No. 2541) 17. 
