548 



U. S. BUREAU OF FISHERIES 



form suspended by ropes to a windlass or lever, by which it is moved 

 up and down in the tank. (Fig. 15.) The salmon or halibut are piled 

 on this suspended platform, which, when loaded, is lowered into 

 the water. One to four dips are given, separated by a moment out 

 of the water for draining off excess water and freezing the glaze. 

 An improvement on this type of glazing tank is a concrete tank partly 

 below the floor level. Instead of the wooden platform a large rec- 

 tangular, heavy, galvanized-wire basket is suspended by a one-half - 

 ton electric hoist. (Fig. 15.) The hoist rides on trolleys on an over- 

 head rail leading from the sharp freezers to the glazing room and 

 from the latter to the elevator, and into the several storage rooms. 

 The wire basket is loaded in the sharp freezer, conveyed into the 

 glazing room, lowered into the water by means of the electric hoist, 



Fig. 16. — Glazing room of a Pacific coast freezer. Halibut, black cod, and salmon 

 are being glazed in the dipping tank. Roller platform scales at left for weighing 

 the glazed fish. Courtesy, Canadian Fishing Co. (Ltd.) 



then raised and conveyed to the elevator and into the storage rooms. 

 From 500 to 750 pounds of fish are handled at a load. 



TEMPERATURE OF GLAZING ROOM 



A fish that is not thoroughly frozen will not glaze properly, 

 especially in warm air, because the fish is of itself not cold enough 

 to freeze a good glaze. A simple calculation will illustrate the point. 

 A 2-pound fish will take, say, a 5 per cent glaze. Assume that the 

 glazing water is at 35°. The fish is 80 per cent, or 1.6 pounds, of ice. 

 As the specific heat of ice is 0.5, then 0.5X1-6, or 0.8 B. t. u., is required 

 for each degree of increase in temperature of the fish. One-tenth of 

 a pound of glaze is frozen on the fish, requiring 14.4 B. t. u. of latent 

 heat and 0.3 B. t. u. to cool the water from 35 to 32°, or 14.7 alto- 

 gether; 14.7-7-0.8=18.4° rise in temperature of the fish to freeze the 



