6 U. S. BUREAU OF FISHERIES. 
exceed 99 per cent. The following example will illustrate the point. 
A chemical analysis of some lot of salt is, let us say: 
Per cent. 
Sodium) chlonide 2 2! 262444...) 4...) 3) eee ee 97. 50 
Moisture 52. sees Se i ee ee es 2 eee 2. 00 
Magnestum]chlonid@ 2 ae Eee a ee a ee ee By 4 
Calenim MSulph abe wes tae ek Re 2) SLE OMe ht eae ce PEARS es ODI AD Ae 25) 
MOGAL Sn Bee a ree se ey re 1 EE ae Ee ie ae 100. 00 
This analysis shows only 97.5 per cent pure salt—which might not 
appear 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 
highly 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 say, $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, APPLICATION OF SALT IN THE DRY CONDITION.—There is very 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, applied 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- 
sary to use the salt dry. 
bout 35 pounds of salt to each 100 pounds of fish is sufficient, if 
well distributed. 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 
