46 BULLETIN 150, U. S. DEPARTMENT OF AGRICULTURE. 
Whether the retorts should be of open type or closed to make possible 
cooking under pressure is debatable, as equally satisfactory results 
apparently are had from both types. 
Beneath the retorts a " slush box,'' or bin, should be constructed, 
of sufficient capacity to hold the cooked fish from at least one^ retort,, 
and provided with steam coils to keep its contents hot. As the ma- 
terial is to be drawn off from this onto frames for the press, it 
should be provided with suitable gate valves for that purpose and 
should be built at such a height that the material could be run onto 
the frames directly by gravity. 
For pressing, at present the method previously described, involving 
the use of " hop cloth " envelopes for the material to be pressed and 
hydraulic power ("rack and cloth" press), must be recommended. 
This is slow and laborious, but effects an efficient separation: and 
at present it has the distinct advantage over all other methods of 
pressing salmon of having been demonstrated as entirely feasible. 
In actual practice at least two men are required to operate the 
press. This number probably could not be reduced, as the placing of 
the frames and especially of the " hop-cloth " squares scarcely could 
be done by one man, as is true also of the removal of these after the 
pressing has been finished. An additional objection to this method 
of pressing is the difficulty of cleaning the frames and cloths. Dur- 
ing the pressing they become covered with the finely divided cooked 
fish. This spoils readily unless removed. To clean them by hand, 
as now practiced, is a tedious method which certainly could be 
improved. 
Adhering, again, to demonstrated forms of apparatus, the steam 
drier must be suggested (PI. VI, fig. 1). A form employed with 
success in one small cannery by-products plant has the shape of a 
drum, 6 feet in diameter and 2-J feet deep. It is steam jacketed and 
therefore must be insulated. For heating it, steam under 20 pounds 
pressure is requisite. Paddles for stirring are attached to a ver- 
tical shaft which is actuated through suitable gearings by a small 
steam engine. A rotary fan serves, to remove the moisture-charged 
air. An opening in the top is designed for filling, with another near 
the bottom for emptying. The latter operation is accomplished auto- 
matically when the paddles are revolved with the lower door open. 
The drier of the above dimensions receives a charge of 1,500 pounds 
of wet material. With this apparatus a small steam engine would 
be required. One of 15-horsepower capacity has been found sufficient 
to operate the drier and the conveyors of the plant. 
As this drier has a rated capacity of only 1,500 pounds of wet mate- 
rial, and as it requires two hours in which to effect the drying, which 
is equivalent to 750 pounds per hour, its usefulness is limited to a 
plant of small capacity. To provide drying capacity for the maxi- 
