174 



Dr. C. A. Burghardt on the 



Sample. . 



No. i. 



No. 2. 



Stannic Oxide (Sn0 2 ) 



66 , o4 



82-84 



Silica 



14*80 



4-20 



Manganese Dioxide 



1*90 



none 



Ferric Oxide 



.. 13-60 



8-04 



Cupric Oxide 



2-48 



4-20 



Calcium Oxide 



0*40 



none 



Bismuthic Oxide ... 



0-08 



1-28 





99-30 



100-56 



I found that 95 per cent of the total tin in the ore was taken 

 up in the first fusion, which I consider a very satisfactory- 

 yield. By the old method of analysis the fusion would have 

 to be performed over a blowpipe for an hour or more and 

 repeated at least three times in order to extract all the tin. 

 For success eitlier by the old process or by my process, an 

 extremely fine state of division of the sample is necessary. 



Quantitative Analysis of Wolframite. 



This mineral is practically tungstate of iron. It is a 

 difficult mineral to analyse by the old methods and much 

 time is required to carry out the different processes. By 

 my process the iron is entirely separated from the tungstic 

 acid at once and remains behind (after solution of the melt 

 and subsequent filtration) on the filter paper as ferric oxide 

 and magnetic oxide. The greater portion of the manganese 

 present in the mineral is also found on the filter paper as 

 manganese dioxide with the iron. In the solution there is 

 tungstate of sodium, manganate of sodium and silicate of 

 sodium. The tungstic acid is thrown out of this solution 

 (along with any niobic acid which may be present) by 

 adding a slight excess of hydrochloric acid and boiling, 

 when the tungstic acid, W0 3 is precipitated out as a yellow 

 powder, dried, ignited and weighed. Of course if niobic 

 acid is present it must be separated from the tungstic acid. 



