REFRIGERATION OF FISF. . 587 



We have seen from the theory of brine freezing that brine that 

 would be liquid at 15° F., at normal atmospheric temperature is far 

 above its freezing point. Under such conditions penetration of salt 

 is bound to be severe. Furthermore, there is no evidence that very 

 rapid freezing or sudden subjection to low temperatures does any 

 harm to the fish. 



mann's method 



For purposes of freezing fish in brine, particularly on steam 

 trawlers. Robert Mann covered by patent 07 apparatus comprising 

 a deep, upright tank, opening above the deck forward but extending 

 through the deck below, where the accessory machinery is located. 

 The tank is filled with refrigerated brine. Openwork cages are pro- 

 vided, in which the fish baskets or containers are placed. This cage 

 is lowered into the tank of brine from the main deck. The brine 

 is refrigerated by a suitable refrigeration machine and is filtered. 

 The arrangement of apparatus permits the freezing operations to be 

 conducted from the main deck without obstruction by machinery. 



hiksch's method 



It will be recalled that in Ottesen's invention it was brought out 

 that when fish are exposed directly to brine for freezing there will 

 be some penetration of salt unless the temperature and concentra- 

 tion of the brine conform to certain specified requirements; namely, 

 that the brine of any particular concentration less than 22.42 per 

 cent of salt be at such a temperature that free ice will exist in it. It 

 was also pointed out that while the required conditions might be met 

 in the body of the brine as a whole, that which is in immediate con- 

 tact with the fish may be warmed by the fish until some penetration 

 of salt occurs. Ludwig Hirsh 58 avoids the formation of a slow- 

 moving film of brine in contact with the fish by suspending or loosely 

 piling them and showering them with brine. By thus preventing 

 penetration he claims that other brine, such as solutions of calcium 

 or magnesium chloride, may be used. He further provides that the 

 fish may be given a glaze by means of a preliminary bath or shower 

 of fresh water, the adhering water film freezing at once when the 

 cold brine touches it. It seems to the present writer unlikely that 

 such a film would really freeze to a glaze under the circumstances. 

 Ottesen makes a similar claim in his patent. 



GOER DE HERVE's METHOD 



The first method to be devised for continuous freezing of fish in 

 brine was that of E. de Goer de Herve, 53 who devised a long tank for 

 brine through which the fish were moved by a combination of wire 

 netting to hold the fish submerged and paddles to keep them in 

 motion. The inventor describes the apparatus and its operation as 

 follows : 



The apparatus consists of two endless chains on which is stretched an end- 

 less band of wire netting with a mesh small enough to retain the smallest fish 



B ' British Patent 144368, 1920. 

 58 German Patent 335871, Apr. 16, 1921. 



s9 La Revue Generale du Froid et des Industries Frigoritiques, October, 1920, pp. 

 291-292. 



