White. — Marine Animal Oils 87 



unfit for use. A properly neutralized fish oil prevents 

 the hardening or setting of the red lead in the package, 

 and a paste of this material can be transported a great 

 distance and will last many months in a fresh and soft 

 condition." 



COD LIVER OIL. 



The production of a medicinal cod liver oil of good 

 quality requires considerable care. Such oil is now made 

 from selected fresh livers, those livers being discarded 

 which are at all discolored. The livers are subjected to 

 the action of steam at a fairly low temperature, (the 

 best oil is obtained when the temperature is not allowed 

 to exceed 70° C.) and the oil rising to the top is skimmed 

 off". This oil is of the first grade, and after filtering from 

 liver tissue, may be bleached by treatment with fullers' 

 earth or by exposure to the sun. Longer heating affords 

 a darker oil, and a brown oil may be finally obtained by 

 pressing the residues. 



Good medicinal oil should be of very light color, slight 

 fishy odor and taste. It should have a small amount of 

 free fatty acids, of volatile acids, and its iodine absorp- 

 tion value should be high. Its medicinal value is very 

 probably not due to the amount of free acids, to the 

 small amount of iodine contained in all cod liver oil, nor 

 to the presence of any bases from the decomposed pro- 

 tein matter of the liver. Lewkowitsch 1 thinks that "the 

 medicinal effect of cod liver oil . . . must be looked for in 

 the facility with which it is hydrolyzed or digested, and 

 >t cannot be doubted that this property is caused by the 

 peculiar constitution of its unsaturated fatty acids. From 

 the medicinal point of view, that cod liver oil is the best 

 which has been prepared from fresh livers and kept pro- 

 ected from the action of light and air." 



There is on the market an oil called "cod oil" which 

 s nothing but a crude cod liver oil. It is prepared in 



'"Chemical Technology and analysis of Oil, Fats and Waxes." 

 ol. II, p. 361. 



