REFRIGERATION OF FISH 615 



from the perforations against the lower side of the plate and warms 

 the plate so that the fillets may be removed. Fresh fillets are then 

 placed on the plate. 



The advantage of rapid freezing of fillets in this apparatus with- 

 out contact with brine is obvious. It is also simple and prac- 

 tical. The advantage of compactness, which it embodies, is of im- 

 portance, inasmuch as the surface required for individual freezing 

 is relatively very large and will take up a prohibitive amount of 

 space if spread out. Two cabinets of 24 shelves each can be placed 

 on a floor area of about 3i/ 2 by 15 feet and will freeze about 500 

 pounds of fillets an hour with brine at 10° F. below zero. The fillets 

 are flat and are frozen straight. 



LIQUID AIR FOR FREEZING 



Liquid air has been proposed as a refrigerant for fish 81 by Bailey. 

 The inventor's container for liquid air was claimed to make prac- 

 ticable the control of temperature in a room by regulating the evapo- 

 ration of the liquid. Even if liquid air were available at a moderate 

 price (which it is not), it would scarcely be suitable for freezing fish. 

 While liquid air has a temperature of about 342° F. below zero, the 

 amount of refrigeration it contains is, pound for pound, actually less 

 than that in ordinary ice. Ice has 144 B. t. u. per pound ; liquid air 

 about 122. It would freeze fish very quickly, but even if frozen in 

 liquid air it would be impossible to hold the fish at anywhere near 

 that temperature. 



WINTER-FROZEN OR NATURALLY FROZEN FISH 



In cold climates in winter fish are taken through holes in the ice 

 and allowed to freeze in the cold winter air. This practice is fol- 

 lowed in Canada, Russia, and other northern countries. 



METHOD OF CATCHING FISH THROUGH HOLES IN THE ICE 



The simplest way is to cut a hole through the ice and fish with a 

 hook and line or a long-handled dip net. For commercial pur- 

 poses a more efficient method is followed, as described by Bobbins 82 

 Holes are cut through the ice at intervals. A long, light pole is 

 lowered into a hole and extended to the next. By this means a line 

 is run from hole to hole, on which a gill net is fastened and let drop 

 into the water under the ice. The fish entangled in this net are 

 drawn out with the net, taken off, and allowed to remain on the ice 

 until they are frozen, or nearly so. The air may be, on occasions, 

 as cold as 40° F. below zero. Snow is gathered, to be used in pack- 

 ing with the fish in wooden boxes, and the fish are packed, if prac- 

 ticable, while they are still slightly soft. The boxed fish are allowed 

 to remain on the ice until the fish are frozen solid and a wagonload 

 accumulates, when they are hauled to a railroad station and shipped. 



81 Bailey, "Liquid air as a freezing agent." Canadian Fisherman, April. 1918. See 

 also, O. Simonis, Liquid Air and It's Possibilities. Proceedings, Fourth International 

 Congress of Refrigeration, London, 1924. Vol. II, See. III. pp. 1094-110:.'. 



82 C. C. Robbing, "The fish production of the Great Lakes of the United States and 

 Canada, and the practical application of refrigeration and cold storage." Proceedings, 

 Third International Congress of Refrigeration, Chicago, 1913, Vol. I, Sec. Ill, pp. 543- 

 552. Chicago. 



