28 BULLETIN 150, U, S. DEPARTMENT OF AGRICULTURE. 
FISH SCRAP FROM SALMON WASTE. 
From preceding paragraphs it is to be seen that during the last 
year a total of 1,630 tons of dried fish scrap and 286,000 gallons of 
oil were manufactured from the waste from salmon canneries on the 
Pacific coast of the United States. The amount of these products 
represents the output of five plants. 
The methods employed in at least four of the five plants in all 
essentials are similar. The differences between them are chiefly in 
mechanical features and in the arrangement of the machinery within 
the plants. The same process is used in all of them. This consists 
in cooking the waste by steam, either in closed retorts under pressure 
or in open retorts, in pressing the cooked fish in one type of press 
to remove the water and oil, and drying the scrap. In the following 
paragraphs the methods in vogue in these rendering stations are 
described in some detail. 
COLLECTING. 
The waste is carried from the cannery to the rendering plant on 
scows. In cases where the floor of the cannery is high enough above 
the surface of the water the refuse from the various " butchering " 
operations can be run through chutes into the scows by gravity. 
There are instances, however, where this is not possible at high water, 
and it has been found necessary to install conveyors for loading the 
scows. These are arranged beneath the cannery floor. The material is 
delivered to them at the bottom of hopper-shaped receptacles which 
receive the waste from the cannery floor. Where the top of the 
scow at high tide is above the level of the cannery floor, two con- 
veyors working together at an angle to each other are utilized, one 
bringing the material horizontally to the edge of the dock to which 
the scow is made fast and the other lifting it over the side of the 
scow. The conveyors may be operated by a small gasoline engine 
or by the same motive power that operates the mechanical cleaner 
or the cutter. 
UNLOADING. 
The charged scow is towed to the dock of the rendering plant, 
where it is unloaded mechanically. An adjustable bucket conveyor, 
of the wheat-elevator type, is rigged in such a manner that its free 
end can be thrust into the mass of material constituting the load of 
the scow. The load is thus lifted and deposited directly, or by means 
of an auxiliary conveyor, into storage bins. From these it is drawn 
off as desired into cooking vats. What is regarded as the best prac- 
tice consists in raising the waste directly to bins situated over the 
cooking vats, which in turn are placed over the presses, so that only 
one lifting is necessary, and the material thereafter may pursue its 
course through the factory by gravity. 
