2(54 EEPORT OF COMMISSIONEE OF FISH AND FISHERIES. 



tons, are placed in the inner cliambor of a revolving cylinder, with 

 double walls, the space between the inner and tlie outer w;ills being 

 filled with steam at about 80 pounds pressure. Before admitting 

 steam the cylinder is put in motion, so that as it revolves each fish is 

 constantl}' changing its position. A uniform temperature is main- 

 tained by means of one head of the inner cylinder being perforated 

 to j)ermit the steam generated in the mass to escape through a safety 

 valve. 



In tlie oil room of the menhaden factories is a series of receptacles 

 into which the oil and water are received from the di-aining tanks and 

 the j)resses. The combined mass of oil and water is first subjected 

 to a temperature of 150° F., which causes them to separate, the oil 

 rising to the surface. It is permitted to overflow to other tanks con- 

 taining hot water, where it is brought to the boiling-point by means 

 of injected steam. It is important that the oil be separated from the 

 water before the imi)urities begin to ferment, fermentation causing 

 it to be dark and of lower grade. After settling for a while the oil 

 is withdrawn into another tank and thence pumjied into the storage 

 tanks. 



A contrivance for withdrawing the oil from the surface consists of 

 a jointed pipe with open end at top, which in some cases is funnel- 

 shaped. This i)asses up through the bottom of the vat, and the top 

 of the pipe is so arranged that it may be raised or lowered to any 

 desired distance beneath the surface to receive and guide the surface 

 oil into the next vat. Sometimes there is a series of as many as 5 

 vats, from one to another of which the oil passes, each time becoming 

 purer and purer as it is cooked and drained. The oil is led into the 

 first of the cooking vats through the bottom, the pipe leading nearly 

 to the surface. A second pipe passing through the bottom and ter- 

 minating with an open toj) not a great distance above the bottom 

 carries off the Avater-oil or less pure oil as it settles and conducts it 

 to near the top of the second vat, where the oil and water are further 

 separated. 



At the bottom of each settling tank is deposited a (juantity of finelj''- 

 divided fleshy substance known as "gurry." Tliis is removed from 

 the tanks to the gurry room, where it is treated or sprinkled with 

 sulphuric acid to facilitate the separation of the oil from the flesh 

 fiber. It is then placed in bags, 2 gallons to the bag, and these jilaced 

 in pairs under a press and subjected to great pressure, resulting in a 

 small quantity of oil. The residuum in the bags, consisting of a hard 

 cake, is broken up and either discarded or mixed with the scrap. 



When thoroughly separated from the water, the oil is pumped into 

 suitable storage tanks or barreled. The refining or bleaching of the 

 oil is rarely done at the factoi-ies, but is perfoi-med by the oil-refiners 

 of New York, New liedfoi-d, IJoston, etc., and the methods and results 

 have already been described on p. 2.'34. 



