﻿48 BULLETIN 2, U. S. DEPARTMENT OP AGRICULTURE. 



of soap without further treatment, and in some cases is placed in 

 stout canvas bags and subjected to pressure to recover the oil which 

 it still contains. The residual solid matter is added to the scrap. 

 As this is free from bones, its nitrogen content is correspondingly 

 higher than that of the ordinary scrap. 



The oil that has been put through the simple process of separation 

 and purification described is run directly into barrels for shipment 

 or into large storage tanks from which it is drawn off as desired for 

 shipment. It usually is sold in bulk to oil refiners by whom it is 

 prepared for the various uses to which it is adapted. 



YIELD. 



The yield in oil varies (1) with the year, (2) more decidedly with 

 the locality from which the fish are taken, and (3) most widely with 

 the time of the year when taken. The fish taken in northern waters 

 as a rule are fatter than those from southern waters. " In the year 

 1900, for instance, the yield of oil at the Rhode Island factories was 

 5.76 gallons per 1,000 fish; in New York it was 6.39 gallons, in 

 Delaware 4.92 gallons, and in Texas 3.51 gallons to the 1,000 fish." 1 

 When the fish appear in the spring they frequently are so thin that 

 no recoverable oil at all is obtained from them. The fish taken in the 

 fall, on the contrary, yield on the average 12 gallons per 1,000 and 

 frequently 15 gallons per 1,000. The variation in yield per thousand 

 from year to year, therefore, probably is determined by the relative 

 number of fish caught in the spring and fall. 



PROPERTIES AND USES. 



Crude menhaden oil varies in color from light amber to dark 

 brown. This wide range in color is due to the variation in the 

 manner of treatment of the fish and the preliminary purification of 

 the oil. Its viscosity is determined largely by temperature. 



Formerly menhaden oil was used principally as an illuminant and 

 in currying leather. In addition, it long has been used as a paint 

 vehicle, as a lubricant, and as a soap-making grease. Its use in 

 currying leather and as an illuminant has been supplanted to a con- 

 siderable extent by that of mineral oils, while its employment in the 

 other manners mentioned has increased. Large quantities now are 

 used in the paint manufacturing industry and in tempering steel. 

 For the latter purpose a large amount is sold directly to the manu- 

 facturers of steel articles. 



Important contributions to the knowledge of fish oils as paint 

 vehicles have been made by Toch. 2 This paint and oil specialist 

 regards menhaden oil as the best of the fish oils. He differentiates 



1 Stevenson, loc. cit. 2 Toeh, J. Ind. Eng. Chem., 3, 627 (1911). 



