248 Examination for Thallium and Indium. 



excess of granulated zink was added to the cold solution, and 

 after the evolution of hydrogen had ceased it was boiled until 

 no more gas was given off. The somewhat bulky precipitate 

 was collected on a filter and well washed. It was then dis- 

 solved in nitric acid, and sulphuretted hydrogen gas passed 

 through the solution. A brown.precipitate formed, which after 

 being well washed was examined before the spectroscope. The 

 filtrate was boiled to expel all of the sulphuretted hydrogen, 

 neutralized with carbonate of soda, and carbonate of baryta then 

 added in the cold. The precipitate formed was dissolved in 

 sulphuric acid and the sulphate of baryta removed. Acetic 

 acid was added and sulphuretted hydrogen gas passed through 

 a second time. 



An examination with the spectroscope revealed the presence 

 of copper, manganese, and lime, but no trace of thallium or of 

 indium. 



2. Franklinite. New Jersey. 



This mineral contained magnetic iron, red oxide of zink, and 

 silica. The powder was digested in hydrochloric acid, and the 

 filtered solution subjected to the regular order of qualitative 

 analysis, and the precipitates in each case carefully examined. 

 Manganese, baryta, and lime were found in abundance, but no 

 trace of thallium or of indium. 



3. Zink olende. Saucon Valley, Pennsylvania. 



This was digested in nitric acid. Sulphuretted hydrogen 

 gave a pure yellow precipitate of sulphide of cadmium, which, 

 however, revealed no lines of indium, but strongly the presence 

 of manganese. 



4. Zink olende. Wurtzboro, New York. 



This blende contains copper, manganese, and lime, but no 

 thallium or indium. 



