1835. j Analysis of Wolfram. 451 



pure nitric acid was added , and the tungstic acid precipi- 

 tated of a beautiful yellow colour. After being well washed 

 with distilled water, acidulated with nitric acid, dried and 

 ignited, it weighed 14-39 grs., or 71*95 per cent. 



B. The undissolved portion which remained on the filter 

 in (A.) was dissolved off by muriatic acid, and the solution 

 neutralized as exactly as possible with carbonate of ammonia. 

 The whole was now boiled with benzoate of ammonia 

 in a flask on the sand-bath, and the benzoate of iron which 

 it precipitated was separated by a filter. After being clean 

 washed, dried and ignited, the peroxide of iron which 

 remained weighed 2*58 grs. = 2*362 grs. protoxide of iron. 



C. The solution and washings from (B.) being evaporated 

 to dryness, the whole was exposed to a red heat, to get rid 

 of the ammoniacal salts. What remained was dissolved in 

 water, and boiled with carbonate of soda. The manganese 

 which precipitated was separated by a filter, and after being 

 well washed, dried, and ignited, weighed 3*37 grs. red 

 oxide = 3*137 protoxide of manganese. 



Hence, we have for the composition as follows : — 



Tungstic acid 14*390 or 71*950 



Protoxide of iron 2*362 „ 11*810 



Protoxide of manganese . . 3*137 ,, 15*685 



19*889 99*445 

 The difference between this and the preceding analysis of 

 Berzelius induced me to make another, and the result of 

 the second, executed in the same way, gave as follows : — 



Tungstic acid 73*60 



Protoxide of iron 11*20 



Protoxide of manganese . . 15*75 



100*55 

 Agreeing* with the first very nearly except in the quantity 

 of tungstic acid. 



If we adopt Dr. Thomson's atomic weight of tungstic 

 acid, as given in the last Edition of his System of Chemistry, 

 and calculate, we obtain the following : — 



atoms. 



Tungstic acid 4.74 or 1*90 



Protoxide of iron .... 2*49 „ 1*00 

 Protoxide of manganese . . 3*50 „ 1*40 

 2g2 



