4 BULLETIN 150, U. S. DEPARTMENT OF AGRICULTURE. 
Table I. — Sources of nitrogen used in mixed fertilizers of the United States. 
{Figures are approximations.) 
Material. 
Amount 
used in Nitrogen Nitrogen 
United content, yielded. 
States. 
Ammonium sulphate 
Sodium nitrate (Chilean) . 
Calcium cyanamid 
Cottonseed meal 
Fish scrap 
Tankage 
Dried blood 
/High. 
■\Low. 
/High. 
•\Low. 
/High. 
YLow. 
Tom. 
215,000 
85,000 
681,000 
388,000 
70,000 
162,000 
99,000 
57, 500 
37,700 
Per cent. 
19.75 
15.5 
18.0 
[ 6.5 
9.0 
11.0 
Tons. 
42, 463 
13, 175 
44,272 
24,320 
6,300 
10,500 
6,450 
6,300 
4,150 
This report is designed for the information of the layman who 
is totally unfamiliar with the fish industries of the Pacific coast, of 
those familiar with the fishing industries but not familiar with the 
fertilizer trade, and particularly of those who are interested in the 
manufacture of fertilizer from fish waste. For this reason all phases 
of the subject are discussed, some of them in such detail as possibly 
to appear extreme to those familiar with these details. Where such 
details are omitted from this report, the literature containing them, 
generally easily accessible Government reports, is referred to where 
possible. The apparatus for use in rendering fish waste is discussed 
in greatest detail, because, of all the items conneced with the indus- 
try herein proposed and advocated, this is considered the one on 
which information is most apt to be lacking and therefore most likely 
to be desired. The writer has been assured of the willingness and 
the desire of many of the operators of canneries to conserve the 
by-products now lost as soon as they are informed of the proper 
methods and apparatus to be used. An especial effort therefore is 
made to present all available information concerning these, and to 
discuss fully their advantages and disadvantages. 
TECHNOLOGY OF CANNING. 
FISHING. 
Salmon for use by the canneries are caught in traps or pound nets, 
purse seines, haul seines, gill nets, and fish wheels. In southeast 
Alaska the greater portion of the fish are taken in traps, owned and 
operated by the packers, while in the Puget Sound region many are 
caught with purse seines and gill nets. On the Columbia Eiver drag 
seines, gill nets, and fish wheels are in general use. 
TRAPS. 
The traps or pound nets are designed to intercept the fish as they 
swim in courses paralleling the shore or passing certain points. For- 
