1890.] 



A Cyanogen Reaction of Proteids. 



205 



This method of performing the test has a great advantage over the 

 way in which it is usually done, as it is much easier to distinguish 

 between the blue of the dissolved cupric hydroxide and the violet due 

 to peptone when ammonia is added than it is between the violet 

 solution given by albumin and the rose-red given by peptones 

 when potash is added, especially if the solutions be dilute. The test 

 with ammonia has also this advantage, that peptones and albumoses 

 can be detected with certainty even if other proteids are present at 

 the same time. 



1 next proceeded to make experiments with nickel sulphate dis- 

 solved in ammonia; the solution so formed is a purplish one, and 

 the results obtained may be tabulated as before : — - 



Proteid. 



Addition of nickel oxide 

 in ammonia produced : — 



Subsequent addition of 



potassium or sodium 

 hydroxide produced : — 



Egg albumin. 

 Serum albumin. 



Witte's peptone. 



G-rdbler's peptone. 

 Pure peptone. 

 Albumoses. 



Faint bluish solution. 

 Faint bluish solution. 



Yellow solution (with 

 flocculent precipitate) . 

 Ditto. 

 Ditto. 

 Ditto. 



Yellow solution. 

 Yellow solution (with 

 flocculent precipitate). 

 Orange solution (with 

 flocculent precipitate). 

 Ditto. 

 Ditto. 

 Ditto. 



This test may thus be used for distinguishing between albumins 

 and the products of proteolytic digestion; the former giving a yellow 

 solution only after the addition of potash or soda, the latter giving a 

 yellow colour with nickel oxide and ammonia alone, which is however 

 deepened to a dull orange by the addition of potash or soda. 



I next proceeded to apply these tests to other classes of proteids, 

 albuminates, globulins, fibrin, coagulated proteid, and mucin; and 

 the results are stated in the following table : — 



