EXAMINATION OF THE PANCREAS. 



79 



(c) Piria's Test, due to the formation of tyrosine sulphonic 

 acid. Pour on a little tyrosine in a dry test-tube some con- 

 centrr 'ed sulphuric acid, place the tube in an actively boiling 



FIG. 5. Leucine ar.d Tyrosir.e. 



water-bath, and leave it there for about half an hour. Let 

 cool, pour into several times its volume of water, rinse with 

 water, arid grind the solution, diluting, if necessary, with 

 barium carbonate, added in portions, until the solution no 

 longer reacts acid. Filter, evaporate to a few cubic centi- 

 meters, and add cautiously some very dilute ferric chloride 

 solution: violet color. 



(d) Reaction of Deniges. Gently heat a small portion oi 

 the tyrosine with 2 to 3 cc. of concentrated sulphuric acid to 

 which a few drops of formalin have been added: brownish- 

 red color, which turns green on the addition of glacial acetic 

 acid. Neither albumin nor peptone reacts with this reagent 

 of Deniges. 1 



1 According to C. T. Morner the reagent is made as follows 



1 volume formalin; 

 45 volumes distilled water; 

 55 volumes concentrated sulphuric acid. 



If a portion of this solution (2 cc.; is treated with a little tyrosine (in the 

 solid form or in solution) and the mixture is heated to boiling, a beautiful 

 r-rc-en color appears. Zeitschr. f. physiol. Chem. 37, 86. O. 



