126 THE FISHING INDUSTRY 



quantities of fishy decomposition products, for example 

 trimethylamine. 



When cooled, many samples of fish oil deposit solid 

 masses of fish tallow (fish stearine). 



Fish oils, and, to a less extent, the marine animal 

 oils, e.g. whale, seal, porpoise, are drying oils like 

 linseed oil, that is they possess to a very marked degree 

 a capacity for absorbing oxygen from the air, and so 

 become thickened and viscous. This thickening is 

 generally induced by blowing air through the warm 

 oil. Oils that have been thickened in this way are 

 known as " blown " oils. 



Blown fish oils are mixed with mineral oils for use as 

 lubricants for heavy machinery. They have been used 

 as vehicles for paints in place of linseed oil, but with 

 somewhat disappointing results. They are used 

 successfully in place of linseed oil in the manufacture of 

 printers' ink, and in making paints for painting smoke 

 stacks. Such paints resist successfully the action of 

 heat and light. 



More particularly, they are used in the leather 

 industry. Fish oils are used chiefly in the manufacture 

 of chamois leather. Ordinary chamois or wash-leather 

 is made from the flesh-splits of sheep skins. The skin 

 is well washed and softened, and freed from hair by 

 treatment with lime. It is then split, and the loose and 

 fatty middle layer removed by a sharp knife. The lime 

 is removed by a short bran -drench and the superfluous 

 moisture is pressed out. The skin is thus rendered 

 porous and easily able to absorb the oil. It is stretched 

 on a table and oiled with fish or whale oil. The oiled 

 skin is folded up and worked for two or three hours in 

 the faller stocks and then shaken out and hung up for a 

 short time to cool and partially dry. The process is 

 repeated a number of times, until all the water originally 



