SALTING RIVER HERRING. 5 
blood will sour if salted at 65° F. In cool climates the blood may be 
left in the fish if desired, as it imparts a distinct flavor, for example, 
in the Scotch method of curing herring. But in warm climates, 
where conditions are unfavorable at best, there is no choice but to 
remove every trace of blood as well as all entrails and roe and the 
head. To do this it is necessary to behead the fish, take out entrails, 
scrape the kidney out (the bloody strip lying under the backbone), 
and wash the fish thoroughly. (A 20-penny wire nail, the head of 
which has been sharpened with a file, makes a convenient instrument 
for scraping out the kidney.) Large fish may be split through the 
back and laid open. The washing should preferably be done by 
rousing the fish in brine of about the strength of sea water, but it 
may be done in cold fresh water. In the case of alewives or river 
herring, the washing operation should also serve to remove scales by 
vigorous rousing. It may seem that if the blood spoils at 65° F. 
the meat of the fish would not necessarily be ruined. But the taint 
of spoiled blood is sufficient to make the entire fish unfit for food. It 
is also probable that the presence of blood may initiate a kind of 
decomposition of the flesh. 
3. Usb OF SALT OF A HIGH DEGREE OF PURITY.—This is the most im- 
portant factor in salting fish in warm climates; yet some people are 
inclined to question the truth of this statement. Fishermen gen- 
erally have no first-hand way of knowing whether or not any par- 
ticular lot of salt is pure, as neither the looks of salt nor the claims 
of advertising matter are always reliable indications of purity. By 
purity is meant not cleanness but the scarcity of foreign substance 
in the salt. Salt may be highly impure yet perfectly white and very 
fine and clean, for the two most objectionable impurities, lime and 
magnesium salts, are white, like salt. On the other hand, salt may 
be dirty or colored, and yet if lime and magnesium salts are absent 
may penetrate and preserve the fish. 
It is therefore necessary to have a salt of a very high degree of 
purity; that is, with less than 1 per cent total impurity. There are 
grades of salt on the market containing a total of less than one- 
tenth of 1 per cent impurity.t| These salts are especially suitable for 
salting fish by this method. Chemical analysis is the only reliable 
guide to purity; most reliable dealers are able to give the correct 
analyses of their brands of salt, and these figures should be required 
before purchase. The figures for sodium chloride (pure salt) should 
be 99 per cent or over—the higher the better, 99.96 per cent some- 
times appearing. The figures for calcium (lime) and magnesium 
salts should be as low as possible. It makes little difference whether 
they are sulphates or chlorides, any salt in which calcium and mag- 
nesium taken together are more than 1 per cent should be looked 
upon with suspicion for salting fish in warm climates. 
The presence of moisture does not cause the salt to be unsuitable. 
If moisture is present, as it usually is, allowance should be made for 
it; pure salt (sodium chloride) and moisture added together should 
* Names of manufacturers of satisfactory brands of salt will be supplied on application 
to this Bureau ; also if analysis of a salt is furnished, the Bureau will, upon request, give 
opinion as to its suitability for curing fish. 
