Apr. IS. 1919 Meat Extracts, their Composition and Identification 13 



Liver extracts are very dark brown, almost black, in color, are very 

 gummy — that is, they are not "short," and their solution in water is 

 dark red, with a trace of fluorescence. 



Spleen extracts are light-chocolate to light yellow-brown in color 

 have a smooth texture, and are very "short." 



Bone extracts closely resemble spleen extracts. 



Other extracts, including heart extract, are darker than spleen extract, 

 but not so dark as liver extract. They are usually very "short," and 

 their solutions are dark, but are not fluorescent. 



QUALITATIVE INVESTIGATION OF EXTRACTS 



In addition to the quantitative differences in extracts qualitative 

 differences have been noted and, based on these differences, qualitative 

 tests have been devised for the identification of liver and spleen extracts 

 either when pure or in the absence of any considerable proportions of 

 true-meat extracts. In mixtures in which liver or spleen extracts are 

 present in only small amounts the tests are not entirely dependable, 

 although in such instances they are as reliable as any other known method. 



ACETIC-ACID TEST 



A qualitative test for the identification of spleen extracts was sug- 

 gested by Robert M. Chapin, of the Biochemic Division, who noticed 

 that the addition of an excess of acetic acid to a spleen extract resulted 

 in the formation of an abundant precipitate. Confirmation of this 

 observation was found in the literature, Hammarsten (7) stating that 

 spleens are characterized by a peculiar protein which is soluble in boiling 

 water, but which is precipitated by an excess of acetic acid. 



Acting upon this information, the writers tested all the commercially 

 prepared spleen extracts (the laboratory-prepared extracts having been 

 exhausted in the quantitative investigation) with acetic acid in the 

 manner described below. 



About 30 cc. of a 10 per cent solution of the extract under examination 

 are boiled, filtered, the filtrate cooled, and an equal quantity of a 10 per 

 cent solution of acetic acid added. 



Extract No. Effect of acetic acid. 



10. Beef spleens A dense, white precipitate. 



11. Hog spleens A dense, white precipitate. 



12. Roast-beef soak water No effect. 



13. Hog livers A slight, dark precipitate. 



14. Bare beef bones No effect. 



15. Regular bones No effect 



16. Beef livers A slight, dark precipitate. 



18. Beef hearts No effect. 



19. Chuck and plate No effect. 



20. Corned-beef cook liquor A very slight yellowish pre- 



cipitate. 



