216 THE WEALTH OF THE SEA 



this has been accompHshed, the steamer comes along- 

 side, and the fish are dipped out of the purse by 

 means of a bailing net and placed in the hold of the 

 vessel. When possible, the menhaden steamers return 

 to the factory every evening to unload their catch. 



The conversion of the fish into scrap and oil is 

 a relatively simple process, involving merely the 

 cooking of the fish, the pressing of the cooked mass, 

 the drying of the scrap, and the separation of the oil 

 and water by settling. The modern machinery used 

 for rendering the fish into oil and scrap looks very 

 complicated, but it handles immense quantities of 

 fish rapidly with very little labor. 



In most up-to-date factories the fish are cooked by 

 live steam as they are being conveyed through a 

 stationary horizontal steel plate cylinder by a con- 

 veying screw. This type of cooking machine receives 

 its supply of fish by means of a mechanical conveyer 

 directly from the fish bins, and delivers the cooked 

 fish directly to the continuous screw press which 

 presses the oil and water from the hot fish. The 

 oil and water flowing from the press are conducted 

 through a trough to a receiving tank, where a pre- 

 liminary sedimentation takes place, and a consider- 

 able quantity of solid matter that has been forced 

 through the press with the liquid is separated. From 

 the receiving tank the emulsion passes to a series of 

 tanks in which the separation of the oil and water 

 gradually takes place. The pressed cooked fish is 

 dried in rotary driers, in which the scrap is heated 

 by hot air as it gradually works its way toward the 

 lower end of the cylinder. 



