48 BULLETIN 2, U. S. DEPARTMENT OF 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 Xew York it was 6.39 gallons, in 
Delaware 4.92 gallons, and in Texas 3.51 gallons to the 1,000 fish." x 
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 Toch, J. Ind. Eng. Chein., 3, 627 (1911). 
