34 BULLETIN 150, U. S. DEPARTMENT OF AGRICULTURE. 
The salmon scrap has a lighter color and more pleasant odor 
than the menhaden scrap. This, again, possibly does not concern 
its fertilizing value, though there is a remote possibility that it 
may affect its demand in the trade. It is said that some agricul- 
turists appraise the value of fertilizer materials by the disagree- 
ableness and strength of their odor. On the contrary, it is a better 
established fact that considerable prejudice exists against fish scrap 
on the part of common carriers and the public in general because 
of its odor. Since nothing is to be lost and something is to be gained 
by reducing the disagreeable odors of fish fertilizer, the point men- 
tioned is favorable to the salmon scrap. The better smell of the 
latter is due most probably in greatest measure to the fact that it 
is dried at moderate temperatures and is not scorched, as inevitably 
must happen in the hot-air driers as now operated on the Atlantic 
coast. It also is true that the menhaden scrap is dried in a stream 
of hot gases generated in a soft-coal fire; the soot from this doubt- 
less contributes likewise to the dark color of the product. 
Another point of difference between the salmon and menhaden 
scrap is introduced by the occasional acidulation of the latter. The 
addition of sulphuric acid to the scrap is practiced most generally 
to disinfect the undried but freshly cooked and warm "pomace," 
and to render it unfit as a breeding place for flies. This is resorted 
to, as a rule, only when the scrap is being produced at a rate greater 
than that at which it can be dried. The acidulation frequently is 
followed by drying. The addition of sulphuric acid to the scrap 
is supposed to be beneficial in that it "fixes the ammonia" and 
renders soluble the phosphoric acid of the calcium phosphate con- 
stituting the bones. While it induces a disintegration and pulveri- 
zation of the scrap, and enables the producer to sell the bone phos- 
phate present as soluble phosphoric acid, at the same time it acts 
as a diluent of slight, if any, fertilizer value, with no rating on a 
fertilizer basis. 
In the foregoing comparison of scrap from salmon and menhaden, 
respectively, it is not intended to convey the idea that the menhaden 
scrap for fertilizer purposes is inferior to that from the salmon. 
It is believed that the ammonia and phosphate of the one is as 
valuable as that of the other. 
FISH SCRAP AS CATTLE AND POULTRY FEED. 
To discuss fish scrap from any point of view other than that of 
fertilizer, perhaps, is beyond the province of this report. It should 
be pointed out here, however, that with such fertilizer materials as 
dried blood, abattoir tankage of high grade, cottonseed meal, and 
fish scrap, it is better agricultural practice to feed these to stock, 
provided, of course, that all barnyard manures be conserved care- 
