Chemical Examination of American Minerals. 31 



analyzing the solution, the following constituents were ob- 

 tained. 



Silica, 30-650 



Protoxide of manganese, - - - - 46*215 



Peroxide of iron, ----- 15*450 



Loss by heat, 7*300 



99*615 



The matter driven off by heat was chiefly water. But 100 

 grains of the mineral gave out when heated, 0*1 cubic inch of 

 carbonic acid gas, 0*16 cubic inch of oxygen gas, and 0*74 

 cubic inch of azotic gas. 



These constituents approach very nearly to, 



3 atoms silicate of manganese, 

 1 atom sesqui-persilicate of iron. 



From the phenomena which took place during the analysis, 

 there could be no doubt that either the iron, or a corres- 

 ponding portion of the manganese, was in a state of deutoxide. 

 We have no means of determining which of the two. 



JVote. This mineral was announced about five years ago, 

 by Professors Vanuxem, and Keating, as a silicate of zinc* 

 Some time after, they published its analysis,f and stated its 

 composition to be. 



Silica, ----- 25*44 



Oxide of zinc, _ - - - 68*06 



Deutoxides of iron and manganese, - - 6*50 



100*00 



* See an account of the Geologj' and Mineralogy of Sparta in New- 

 Jersey, in Vol. II. of the Journal of the Philadelphia Academy, 

 t Ibid. Vol. IV. p. 10. 



