FISH PRODUCTS 125 



however, these globules are heated the skin shrivels, 

 the oil globules expand and burst the skin, and the liquid 

 oil is liberated and can then be extracted from the flesh 

 by pressure. To obtain the oil, therefore, the fish are 

 boiled or steam heated in large vats until the oil is set 

 free. The hot mass is then placed in a press and the oil 

 squeezed out. The residue is made into cattle food and 

 fertilizer. 



In obtaining the best sorts of liver oils, e.g. codliver 

 oil, the livers are taken from the fish as soon as they are 

 caught, and are heated in steam- jacketed vessels until 

 the cell membranes burst and the oil exudes. The oil 

 is then separated by pressure. 



Inferior qualities of oil are obtained by treating 

 putrid livers in the same way at the end of the voyage. 

 These tainted liver oils are unfit for medicinal purposes, 

 but are used in large quantities in the leather industry. 



Blubber (which is from 8 to 20 ins. thick) is stripped 

 from the whale as soon* after capture as possible. 

 Generally the dead whale is made fast alongside the 

 whaler, a deep, spiral cut is made round its body, and the 

 blubber is stripped off and hauled aboard. This is then 

 cut into pieces, chopped up in mincing machines and fed 

 into melting pans and heated with steam, often 

 under pressure. The oil gradually exudes and 

 collects upon the water, the cell membranes, etc. the 

 greaves settling to the bottom. At the conclusion 

 of the boil, the oil is drawn off from above the aqueous 

 (gluey) layer, and is clarified by straining through sieves 

 or filters. The " greaves " is placed in hair or woollen 

 bags and submitted to hydraulic pressure, by which 

 means a further quantity of oil is obtained. 



Fish oils, unless specially purified for medicinal pur- 

 poses, are dark-coloured liquids, with a characteristic, 

 unpleasant, fishy smell, due to the presence of small 



