328 M. Vauquelin on a [May^ 



of the sulphuric acid and manganese on the soap ley; for, 

 beside the iodine and oily substance already mentioned, there 

 are formed some white transparent acicular crystals, at the com- 

 mencementofthe process, before any iodine has risen; but they are 

 soon dissolved by water which rises subsequently. And towards 

 the end of the process, some opaque, yellow, arborescent crys- 

 tals form ; the former I could never obtain in quantity to 

 examine ; the latter I found to be a compound of iodine and 

 carbon, which I have since formed by the action of iodine and 

 potash on alcohol.* 



Article III. 



On a new Variety of Wolfram, or Tungstate of Iron. 

 By M. Vauquelin.f 



MM. DELHUYAa were the first who folmd in wolfram the 

 acid which Scheele had discovered in the tungsten or calcareous 

 tungstate of the Swedes. They discovered moreover that this 

 mineral was mixed with oxide of manganese ; but they did not 

 attempt to ascertain the state or proportion in which it existed 

 in it. 



Some years afterwards M. Hecht and I performed a fresh 

 analysis of wolfram at the School of Mines, the results were, 



Tungstic acid 67 



Oxide of iron 18 



Oxide of manganese 6 



"91 



Lastly, M. Berzelius, in his Determinations of the Elements 

 of inorganic Matter, fixed the composition of this mineral as 

 follows : 



Tmigstic acid 74*666 



Oxide of iron 17-594 



Oxide of manganese 5*670 



97*930 



M. Berzelius, supposing that the iron and manganese existed 

 in the wolfram in the state of protoxides, calculated the relation 

 between the oxygen of these bases and that of the acid. 



M. AUuau, sen. who has always, as is well known, much occu- 

 pied himself with the mineralogy of his country. Haute- Vienne, 

 has lately sent me for analysis, among other minerals, a speci- 



♦ See Annals of Philoiophy, NewSerieSj No. 55, p. 14. 

 -{• Annales de Chimie et de Physique, 



