No. 3 (1921) MANUFACTURE OF FISH OIL AND GUANO 177 



to the length "and character (steam or open fire) of the boiling and 

 the want of freshness in the fish, which however, is seldom a fault 

 at Tanur owing to the system of rapid steam boiling. It is possible 

 to run off the surface stratum of water and oil automatically by a 

 pipe with an orifice placed at the proper level, or by a swivel pipe 

 to take off the fluid at different levels when the pans are not full, 

 but with small operations and cheap labour hand skimming is 

 very effective ; still the automatic method is elegant, cheap, and 

 rapid. 



The skimmed oil is, at Tanur, kept separate from the drained 

 and pressed oil being of very high quality, described by a British 

 firm in England as "unique" and worth several pounds per ton 

 above ordinary oil. 



The considerable quantity of water in the boiling pans and 

 the lengthy steam pipe further enable the heating to be rapid and 

 equal ; every fish is equally heated and the pans show inappreci- 

 able differences of temperature at various points when tested 

 with the thermometer. Moreover, the boiling mobile mass is easily 

 stirred and broken up or moved about with wooden paddles with 

 the minimum of labour, while the high pressure (60 to 80 lb.) steam 

 is itself an important and effective agent in the necessary stirring 

 and breaking up of the fish. 



65. On opening the sluice valve the mass of fish and water, 

 except the water below the level of the valve orifice, readily trans- 

 fers itself owing to its comparative fluidity, to the draining trough 

 which is a masonry or wooden trough the bottom of which is just 

 above floor level : a false bottom of wire gauze, plaited bamboo, 

 coir mat or other material which will readily let water through but 

 retain the fish, is fitted two or three inches above the bottom, and 

 by this means the mass is readily relieved of much of its water ; 

 this addition to ordinary methods is important. A good deal of 

 good class oil passes with the water, but is now sent direct into 

 -the pressed oil pits, since the pressed oil at Tanur is practically as 

 good as the drained oil and little inferior to the skimmed oil. 



66. The well-drained mass is then scooped into coarse coir bags 

 holding about 80 lb. each which are found to resist the pressure of 

 manual presses perfectly, while not allowing much of the solid 

 matter to pass. Two bags are placed in the press, and when half 

 pressed a third is added : the wheel of the press is run by three or 

 four men, and a lever is added to give the final pressure. The 



