112 



THE FISHING INDUSTRY 



that in order to avoid the possibility of " souring," the 

 fish should be salted with the least possible delay. 



(c) The Quality of the Salt. (1) Its Purity. The 

 impurities commonly present in Fishery Salt are the 

 sulphates and chlorides of calcium and magnesium. 



The following analysis show the composition of 

 typical samples of Fishery Salt. 



The Spanish and Italian salts are solar salts, obtained 

 by evaporating sea-water by the heat of the sun. Solar 

 salt nearly always contains more magnesium salts 

 than brine salt does. This constitutes a serious 

 disadvantage to the fish curer. 



Of the calcium salts which occur as impurities in 

 Fishery Salt, the sulphate is practically insoluble in 

 brine, and is probably without action upon the salting 

 process. 



Calcium chloride, on the other hand, resembles mag- 

 nesium chloride and is an undesirable constituent of 

 Fishery Salt, for calcium chloride, and to a lesser extent 

 magnesium chloride and magnesium sulphate, diminish 

 the rate at which the salt penetrates the fish. Curing 



