ELISHA MITCHELL SCIENTIFIC SOCIETY. 105 



No. XXXVII. 



NOTE ON A NEW TEST FOR IRON. 



F. p. VENABLE. 



A solution of cobalt nitrate to which strong hydrochloric acid 

 has been added, is blue. It was noticed that when some impure 

 hydrochloric acid was used a green color was gotten instead of 

 the blue. This change was traced to the iron in the acid, and as 

 I have seen no mention of it elsewhere, I venture to give the 

 present notice of this test. It is very simple, rapid and delicate 

 for detecting traces of iron and is especially useful in testing 

 strong acids. The delicacy of the test is such that when even 

 TFoVo 0" ^^ ^ gramme of a ferric salt are added to the blue strongly 

 acid solution mentioned abov^e, the green is clearly given. With 

 a somewhat larger amount this green is quite vivid. If too 

 much of the ferric solution is used the cobalt solution becomes 

 pink from the addition of water. The test is not given by fer- 

 rous salts, nor does the presence of ferrous salts interfere with it. 

 I have thought that the green was due to the addition of yellow 

 ferric chloride to blue cobalt solution. Other yellow solutions 

 which I have tested failed, however, to give the green. 



ELECTROLYSIS OF WATER. 



[See figure at back of Journal.] 



F. P. VENABLE. 



A short note recently appeared in the Journal of Analytical 

 Chemi.stry (No. 3, 1887, p. 287), describing a simplification of 

 the ordinary condenser. Adopting, in part, the same idea, I have 

 devised the following simplification of ITofmann's apparatus for 

 the electrolysis of water. This will prove useful where the high 



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