Prehistoric animals long extinct are sometimes found firmly embedded in the Polar ice, as fresh as they were on the day they were drowned. It is found that the stability and subsequent quality of frozen meat or fish depend directly upon the manner in which it has been frozen. It may be frozen in air, or when immersed in brine. Of these two methods the latter is much quicker, because brine is over twenty-five times as good a conductor of heat as air is. During the slower air-freezing process the quality of the flesh is impaired by the separation of the contained water into comparatively large crystals of ice. This leads to the displacement of the membrane and tissues of the meat, so that in thawing again the meat drips and becomes tough. When immersed in brine freezing occurs too rapidly for this separation of water to occur to any marked extent. The keeping qualities of brine-frozen fish also are greater than those of air-frozen fish, owing to the protecting coating of ice which effectively prevents contact with bacteria or mould spores. (3) By drying. Primitive man preserved his meat by drying it in the sun, or in the smoke of a fire. To-day the preparation of fish, dried fruits, desiccated vegetables, etc., is a world-wide industry. Generally speaking, decay organisms can only develop in a moist environment. All fresh foodstuffs contain a large proportion of water. The removal of this water effectively checks decay. Drying alone, however, does not always produce a permanent “cure,” as the foodstuff is always liable to get moist again. For that reason it is customary to combine the drying process with treatment with an antiseptic substance such as salt. Smoke drying is better than sun drying, for although the ultra-violet rays of the direct sunlight effectively kill bacteria and mould spores wood smoke contains antiseptic substances with which the meat becomes impregnated, so that even the chance of any subsequent infection is greatly reduced. (4) By treating with an antiseptic substance such as salt. Antiseptic substances differ from disinfectant substances in that they do not kill micro-organisms, but only arrest their development. As a rule, they are effective preserving agents, and do not make the food poisonous or unpalatable. All these methods can be, and are, used for preserving fish, the method most commonly used being treatment with salt. Fish, however, are often kept in ice on board during a fishing trip and are then either packed in ice for transit under special storage conditions (if required fresh) or they are salted down. =Methods of Salting.= Different methods of salting are used, according to the character of the fish and the locality. The fish are either cleaned (split and gutted) or salted “round” (whole). In general, the method used is one of the following— (1) DRY-SALTING. The fish are cleaned, rolled in dry salt, and packed in layers in open casks. Each layer of fish is covered with a layer of salt.