56 JOURNAL OF ELISHA MITCHELL SCIENTIFIC SOCIETY. 



solution of sodium sulphite and afterward 2 drops of the pyro- 

 gallic solution and a pui-ple color wdl be developed. 



This test with distilled water alone develops a light pink 

 shade, which, however, soon fades. This is due to the trace of 

 free ammonia which it usually contjtins. Iron produces a pur- 

 ple tint. The test is so delicate that it will detect iron in 100 

 cc. of water, in which a bright cambric needle has been 

 immersed for an hour. 



Fayetteville, N. C. 



(Issued September 23, 1890). 



