Examination for Thallium and Indium. 217 



XXX. — Examination of American Blendes for Thallium 



and Indium. 



By Charles A. Jot, 

 Professor of Chemistry in Columbia College, New York. 



Eead February 26, 1866. 



Since the discovery of Thallium by Crookes, in the deposits 

 of the sulphuric acid chambers and. the pyritous ores of Eu- 

 rope, and of Indium by Keich and. Kichter in the zink blende of 

 Saxony, the presence of these rare metals in the ores and mine- 

 rals of other countries has become a matter of general interest. 

 With a view of adding to our knowledge of the subject I have 

 examined, a number of specimens of ores and deposits from 

 American localities, and although the results have generally 

 proved of a negative character, it may be of sufficient interest 

 to have them communicated to the Society. 



Through the kindness of Professor Richter, who presented to 

 me some metallic Indium and some of the sulphide, I was able 

 to determine the position of the Indium lines upon the scale of 

 my spectroscope. The Thallium line was determined from a 

 specimen of the sulphate furnished to me by Dr. Hugo Miiller 

 of London. 



The spectroscope employed was made by Dnboscq, and con- 

 sisted of one flint glass prism having an angle of 50°, and a 

 viewing telescope of ten inches focal length. 



In the resolution of the minerals and the preparation of the 

 material, I pursued the methods suggested by Reich, Richter, 

 Winckler, Schrotter, Crookes, and Bottger. 



1. Blende. Ellen ville, New York. 



The mineral containing a small quantity of galena and copper 

 pyrites was finely pulverized and washed. It was then digested 

 for twenty-four hours in hydrochloric acid and filtered. An 



