238 maCrAs fisheries bulletin vol. XIII, 



and greasing pottery moulds, and of course, steel tempering, the 

 brown colour is generally immaterial and decoloration therefore 

 unnecessary, except as an incidental adjunct of purification where 

 such is necessary in order to render the oils neutral and free from 

 unpleasant and improper odour. 



138. On consideration of the previous paragraphs 125 to 137, it 

 will be seen that refinement except of a simple character, viz., 

 steaming and treating with alkalis of which sodium carbonate is 

 simple, cheap, and efficacious, is seldom necessary or profitable 

 except in the case of the better class oils which are to be fitted for 

 edible or medicinal purposes. What is mostly desirable in these 

 cheap fish oils is proper initial preparation; if this be observed 

 little subsequent or complicated refinement is needed or desirable ; 

 if fish oil is prepared from sound materials, separated rapidly from 

 water and impurities, and properly stored, refinement will hardly 

 be necessary save for special purposes ; the unrefined oil will sell 

 well for general purposes, while, if refinement is desired, steaming 

 and treatment with sodium carbonate should suffice, though sunlight 

 bleaching may be useful if hereafter found successful. 



It will also be noticed that the above simple method of refine- 

 ment produces many useful effects siniitltancoiisly ; steaming 

 drives off volatile malodorous acids, washes the oil, coagulates 

 (especially with alkali) any suspended impurities such as the 

 proteins and albuminous matters and causes their precipitation ; 

 the alkalis and steam destroy ferments and neutralize acidity ; the 

 oil is thus simultaneously purified, deodorized, bleached, cleared, 

 and brightened, especially when any subsequent drying removes 

 all residual moisture. 



139. All fish oils contain a quantity of " stearine " (so called) or 

 " fish tallow " which is a whitish fat deposited by the oil, and 

 amounts to about 25 to 33 per cent of the whole quantity— see para- 

 graph 39 regarding menhaden stearine and paragraphs I03and 104 

 on the general subject. As shown in those paragraphs the only 

 way to remove stearine entirely is by winter cooling or by artifi- 

 cial refrigeration coupled with powerful pressing ; none of these 

 is available on the West Coast, so that it is only possible to remove 

 stearine by decantation of the clear oil after settling ; the remain- 

 ing stearine, which contains a good deal of oil, can be strained or 

 filtered and will then give up, but only imperfectly, some of the 

 entangled oil. Fortunately, for all technical purposes the stearine 



