NUTRITIVE VALUE OF FISH AND SHELJLFISH 539 



under proper pressure an intimate mixture of finely divided nickel 

 or other catalyst, hydrogen, and the oil to be hardened. Tlie hydro- 

 genation of fish fats is doubly successful. First, as pointed out 

 above, it deodorizes the fat, and, second, by this process it is possible 

 to harden the hquid fats to the consistency of lard. 



From the foregoing it is evident that when economic conditions 

 demand it chemists will be able to transform fish fats into products 

 suited to the consum.er's taste. Furthermore, it is evident that there 

 must be an ever-increasing supply of edible fats, for the present-day 

 dietitian feels that the human diet to be satisfactory should contain 

 a certain percentage of fats. It therefore appears to be only a ques- 

 tion of time until fish fats will be more extensively used in the human 

 dietary. 



SUMMARY 



Fish and marine animal fats have somewhat the same composition 

 as the terrestrial fats. Due to their greater power to absorb oxygen, 

 they should be protected from the air during storage. 



From the data at present available it appears that fish fats are as 

 completely digested as terrestrial fats of like melting point. 



The use of fat-rich fish increases the fat content of the diet by 

 adding fish fats in a very palatable form. 



The energy value of the separated fish fats is equal to that of the 

 common salad and culinary fats. 



Some of the fat-rich sea foods, such as canned sardines, sahiion, 

 and shad roe, have an energy value equal to that of popular hearty 

 foods such as veal, milk, sirloin steak, and baked beans. 



Fish fats such as the liver oils are the richest known natural source 

 of the essential fat-soluble vitamins. 



Fish fats are available in large quantities and may be modified to 

 suit requirements by various refining processes whenever economic 

 conditions warrant. 



IV.— MINERAL CONSTITUENTS OF FISH AND SHELLFISH 



By Harden F. Taylor, Vice President for Investigation and Research, Atlantic Coast 

 Fisheries Co. Formerly chief technologist, United States Bureau of Fisheries 



INTRODUCTION 



Perhaps every student taking his first course in chemistry has 

 wondered what would happen if some of all the chemicals were 

 dumped in a big jar and allowed to react as they would. The ocean 

 is such a reaction jar on a v»^orld scale. Into it the rivers have for 

 geologic ages been unceasingly delivering the washings of the land, 

 containing the soluble compounds of the earth, and leaving them 

 there, the water being distilled as rain to return and percolate through 

 the earth again and again. Volcanoes have thrown their ashes and 

 dusts high into the air to settle do\vn in the ocean or be carried down 

 by the rains. Springs issuing from the earth bring out large quan- 

 tities of dissolved matter from below the surface, and the cosmic 

 dust and meteors coming from distant space add another part to the 

 constituents of the sea. Furthermore, these chemical compounds 

 that find their way into the sea that we think of as insoluble in water 



