48 BULLETIN 150, IT. S. DEPARTMENT OP 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 (PL 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- 



