10 FISHERY INDUSTRIES OF THE tTiSTITED STATES. 



FISH OILS. 



The demands and uses for fish oils are increasing and the prices are 

 unusually high. Among the various uses are the following: Drying 

 oil in paints and varnishes, stuffing grease for leather, in soap-malting, 

 lubricating compounds, tempermg steel, screw-cutting, and cordage 

 manufacture, for medicinal and iflmninating purposes, in the manu- 

 facture of rubber substitutes, top dressings for automobile tops, awn- 

 ings, tents, and the like, in lara substitutes, etc., after hydrogenation. 



In recent years the annual production of fish oils has ranged from 

 about 5 to 6 million gallons. Of this, more than half is menhaden oil, 

 whale, sperm, and herring oil being produced in appreciable quanti- 

 ties with smaller amounts of other oils, such as cod liver, shark liver 

 (including dogfish), salmon, tuna, sardine, porpoise blubber and jaw 

 oils, seal, and walrus. Imports entered for consmnption for the fiscal 

 year ended June 30, 1918, amounted to 4,881,982 gallons, valued at 

 $3,638,749, and exports in that year were 455,629 gallons, valued at 

 $446,589. 



Realizing the importance of determining more definitely the special 

 properties of those oils for which such information was lacking, to 

 indicate the uses to which they are best suited, the Bureau has made 

 analyses of the body and liver oils of species of sharks, of skate-liver 

 oil, tuna and yellowtail oil, and has furnished the educational bureau 

 of the Paint Manufacturers' Association of the United States various 

 samples of fish oils for analysis and trial as to suitability for use in 

 the manufacture of paints and varnishes. 



Albacore or tuna (Germo alalunga) oil is particularly mteresting 

 because of its excellent drying qualities. It possesses very little 

 unsaponifiable matter and Tittle odor and is pale in color. Drying 

 tests made by the director of the educational bureau of the Paint 

 Manufacturers' Association of the United States showed that it dries 

 even more rapidly than linseed oil. The 1919 production of albacore 

 (Germo alalunga), yeUowfiii tuna (G. jnacropterus) , and blue&i tuna 

 ( Thunnus thynnus) oil in southern California is estimated to exceed 

 100,000 gallons. An analysis of the albacore oil gave the following 

 results: Specific gravity at 15.5° C, 0.9298; acid value, 0.24; saponi- 

 fication value, 195.9; iodine value (Hanus), 184; refractive index 

 (40° C), 1.4755; titer test of fatty acids in degrees centigrade, 20.8°; 

 neutralization value of fatty acids, 182.5; mean molecular weight of 

 fatty acids, 307; total unsapcwiifiable matter 0.80 per cent. Tests 

 with the oil of the yellowtail (Seriola dorsalis) indicated that it was 

 fully as satisfactory for the manufacture of paints as menhaden oil, 

 but not as good as the albacore oil. Its color was light and its odor 

 not strong. 



There is need for more exhaustive investigations of fish oils, for 

 determining definitely the qualities of the oils of various species of 

 sharks, skates, and other fishes serving as sources of supply of fish 

 oils ; for determining more definitely the possibilities ot hydrogen- 

 ating fish oils for use for edible purposes, their nutritive values based 

 on investigations by experts in vitamines, etc. On the subject of 

 hydrogenation. Bulletin No. 769 of the United States Department 

 of Agriculture, February 10, 1919, page 39, states: 



_ Recently a refining process in which hydrogen instead of steam is used to blow the 

 oil has been developed. It appears that it is now possible to remove the disagreeable 



