6 U. S. BUREAU OF FISHERIES. 



exceed 99 per cent. The following example Avill illustrate the point. 

 A chemical analysis of some lot of salt is, let us sslj : , 



Per cent. 



Sodium chloride 97. 50 



Moisture 2. 00 



Magnesium chloride . 25 



Calcium sulphate .25 



Total 100.00 



This analysis shows only 97.5 per cent pure salt — which might not 

 ai)pear suitable for fish. But allowance must be made for the harm- 

 less moisture present. Strictly calculated, after this allowance is 

 made, there is found to be 99.49 per cent pure salt; practically the 

 same result (though not absolutely correct), 99.50 per cent is the sum 

 of pure salt and moisture. The sample is therefore very pure and 

 suitable for salting fish. 



Calcium and magnesium in salt, even in small quantities, greatly 

 retard penetration, so much so that in warm weather the fish may 

 spoil before the salt strikes through. But in cold weather in north- 

 ern climates salt containing considerable quantities of these sub- 

 stances may be used successfully. It will be noted by those who use 

 highlj^ purified salt that the fish do not become white and firm as 

 they do with ordinary Turks Island, Trapani, or other crude salt. 

 The lime and magnesia have a hardening effect on fish, and they 

 whiten the flesh by coagulating it, as heat whitens the white of egg. 

 Nevertheless, the somewhat yellowish, soft fish, produced in pure salt 

 is equally as well preserved as the hard fish in crude salt, is milder 

 and richer in flavor, and soaks out more quickly. This may be some- 

 what difficult to introduce in a market that has been accustomed to 

 a hard, white fish, but the consuming public should not be long in 

 discerning the superiority once the purer fish is distributed. 



It may be objected that pure salt is too expensive. The crude salt 

 may be, let us sa}^, $10 per ton and pure salt $25, a difference of $15 

 per ton more for the pure grade. Fifteen dollars per ton is three- 

 fourths of a cent per pound ; about 35 pounds of salt will suffice for 

 100 pounds of fish. The difference in cost for salt is therefore about 

 27 cents per 100 pounds of fish, or one-fourth of a cent per pound on 

 the basis of the above assumption. The loss of a few barrels of fish 

 (including the labor that was put upon them) will cover the cost of a 

 large pile of pure salt. In very warm climates, in salting river 

 herring, pure salt is necessary to safety. 



4. Ai'PLTCATTOx OF SALT TN THE DRY CONDITION. — There is vcry ex- 

 tensive business in both dry salting and brine salting or pickling fish. 

 In the case being considered, where the greatest speed of penetration. 

 is necessary, the dry salt must be used, for, api:)lied in this way, it 

 penetrates much faster than brine. Again, the fisherman fortunately- 

 located in a cool country may follow his discretion, but the fisherman 

 who works under the handicap of a warm climate will find it neces- 

 rary to use the salt dry. 



About 35 pounds of salt to each 100 pounds of fish is sufficient, if 

 well distril)uted. The fish should be rolled in the salt (which should 

 be fine grained), the belly cavities filled, and the fish packed backs 

 down in tubs so as to hold the salt until it dissolves. These tubs may 

 be made by sawing barrels in two in the middle. A weight should be 



