1 6 Journal of Agricultural Research voi. xvii. No. i 



Mixtures of liver extracts with chuck and plate extracts in varying 

 proportions were prepared for the purpose of determining the delicacy 

 of the reaction, and it was found that the characteristic color was recog- 

 nizable in an extract containing 20 per cent of liver extract; smaller 

 quantities gave a purple color, but it was not sufficiently distinct to be of 

 value. 



In all cases where a positive reaction is obtained and in which the 

 other factors, such as creatinin, nitrogen, etc., indicate the absence of 

 liver extract, the sample should be examined for starch and cane sugar. 



It may be stated that, aside from its value in indicating the presence 

 of liver extract, the Molisch test is necessary in a routine examination 

 for the rapid detection of carbohydrates which may have been added to 

 meat extracts.^ In the analyses of some hundreds of extracts a true- 

 meat extract has never yielded a positive reaction with this test, and 

 whenever a positive reaction is obtained in an extract which can be 

 shown to contain no liver extract it is due to added carbohydrate. In 

 such instances the test should be supplemented with a more complete 

 examination to identify the carbohydrate thus indicated. 



COPPER TEST 



During the course of the investigation it was also noted that the ash 

 of liver extracts in every instance exhibited a more or less pronounced 

 greenish color, which was not observed in the ash of any of the large 

 number of other kinds of extracts examined. As the presence of copper 

 in livers has been demonstrated, it having been found even in the liver 

 of the fetus, the presence of copper in the ash of extracts other than 

 those prepared from livers should be considered. As practically all the 

 commercial extracts prepared from other tissues and organs underwent 

 the same course of preparation, and no copper was thus indicated in 

 the ash of any of the resulting products, it woul4 seem that this test 

 would apply alone to the ash of extracts obtained from livers. If, 

 however, copper utensils are used in the preparation of an extract its 

 presence in limited amounts could probably be readily demonstrated by 

 chemical methods, but a greenish-tinted ash should always lead one to 

 suspect the presence of liver extract. 



Procedure suggested in the identification of an extract : 



1. Total solids. 9. Creatin. 



2. Ash. 10. Molisch test. 



3. Sodium chlorid. 11. Acetic-acid test. 



4. Total phosphoric pentoxid. 12. Test for starch and sugar if a 



5. Inorganic phosphoric pentoxid. positive Molisch test is given. 



6. Total nitrogen. 13. Test fornitrates. 



7. "Meat-base" nitrogen. 14. Test of ash for copper. 



8. Preformed creatinin. 



' Asan illustration of thevalueof this test, regardless of its value in detecting the presence of liver, several 

 extracts have been examined which conformed in every respect to pure-meat extracts with the exception. 

 that they gave a positive Molisch test. Upon investigation the presence of sucrose was demonstrated- 



