It is evident that it is with extreme difficulty that the presence of these adulterants can be detected, especially if they are used in small quantities. The only certain method of guarantee of the purity of a cod liver oil is in the proper inspection and control of the manufacturing works. The livers of many other kinds of fish are employed in the manufacture of cod liver oil, but the other varieties have little value as compared with the cod liver oil itself and they are probably used almost exclusively in the adulteration of the genuine article. The Norwegian cod fish gives a much better character of oil than those coming from the Atlantic coast of America. In fact the latter product is of little medicinal food value and is used chiefly in the leather trade.
Blubber Oil.—Blubber oil includes the oils made from seals, whales, turtles, etc., and is used exclusively for technical purposes, unless surreptitiously placed in cod liver oil as an adulterant.
