490 MARINE PRODUCTS OF COMMERCE 



and the cheaper grades of toilet soap. Some is also used for the preparation of 

 certain lard and butter substitutes. In Europe menhaden and other fish oils and 

 whale oils are hydrogenated and used in the manufacture of candles, soap, 

 leather dressing, table and cooking fats, and other edible and nonedible products. 

 The iodine numbers of such hardened oils vary from about 8 to 70, depending 

 upon the quality; the lower the iodine value the higher the quality. 



Some menhaden oil is used in the manufacture of artificial leather and as a 

 quenching medium for tempering steel products. Another use is in soaps con- 

 tained in insecticidal sprays. It is used in printer's inks and textiles and as a core 

 oil in the foundry. These are not highly important uses as they require only small 

 amounts of the total production. 



Menhaden oil is also used in the manufacture of paints, varnishes, and stains. 

 For this purpose winter oil must be used as stearic acid forms insoluble com- 

 pounds with drying substances. These insoluble compounds slowly precipitate out 

 from the varnish or paint on standing and cause flecks in the film. Menhaden oil 

 is especially valuable in the preparation of certain heat-resisting paints. For roof 

 and barn paints and coatings for structural steel menhaden oil is excellent be- 

 cause the dried film is not as brittle as that formed by linseed oil, and it is some- 

 what less affected by sudden changes of temperature. Heat-treated oil containing 

 driers must be used as raw-oil film is somewhat tacky even when completely dry. 

 In white paints rather large amounts of driers are required to dry the oil to a 

 permanently hard film, and thus prevent the darkening caused by dust adhering 

 to tacky film. 



Formerly, its principal use was in the currying trade and in the manufacture of 

 degras and sod oil; large quantities are still employed by leather manufacturers. 

 Some are used in the manufacture of linoleum and for making rubber substitutes 

 and water-proofing compositions. 



Small amounts of menhaden oil are used in animal and poultry feeds when it is 

 found to contain sufficiently high vitamin A and D. This use is of minor im- 

 portance. 



Miscellaneous Oils. Three species of herring are used in the manufacture of 

 oils. The herring (Clupea harengus), which are taken off the coast of Maine, 

 are caught primarily for canning. Only those which are too large to can and those 

 in poor condition go to the reduction plants. 



Alaska herring (Clupea pallasii), found in Alaskan waters, are used in con- 

 siderable quantities for the production of oil and meal. This species is used to 

 some extent for salting and smoking. 



Alewife or river herring (Pomolobus pseudoharengus and Pomolobus aestivalis) 

 are found in the Chesapeake Bay area. The reduction of these species is incidental 

 to the curing indushy, and the production of oil and meal is small. Herring oil is 

 used in the feeding industry and in the production of soap. In Norway herring 

 oil is refined and used as a substitute for olive oil in the sardine-canning industry. 



Anchovies furnish a source of oil on the Pacific Coast. Oil from this source is 

 not of great importance, and it is usually produced along with the pilchard. 



Salmon oil is produced from the reduction of cannery waste, and is used 

 primarily in animal feeding. It is refined to some extent before being marketed. 



Tuna oil is produced as a by-product of the canning industry. When the tuna 

 are precooked prior to canning, the oil is recovered and used as a feeding oil. 



