Chemical Examination of American Minerals. 39 



muriatic acid ; the iron was thrown down by benzoate of 

 ammonia, and the manganese by chloride of lime. The pre- 

 cipitate is red, and after ignition, six of it is equivalent to 

 five deutoxide of manganese. The zinc was finally thrown 

 down by means of hydrosulphuret of ammonia. 

 The constituents of the mineral were found to be, 



Peroxide of iron, ----- 66-10 



Deutoxide of manganese, - _ - - 14*96 



Oxide of zinc, -___-_ 17'425 



Silica, 0-204 



Water, 0-560 



99-249 



Thus my analysis agrees very nearly with that of Berthier, 

 and serves to confirm it. 



Whether franklinite constitute a peculiar species, or is to be 

 considered as merely a variety of magnetic iron ore, is a ques- 

 tion of some difficulty. The hardness, specific gravity, and 

 even the crystaline form, agree nearly with those of magnetic 

 iron ore. But the composition of the two minerals is quite 

 diflerent. Magnetic iron ore, by the analysis of Berzelius, is 

 a compound of, 



2 atoms peroxide of iron, - - - JO 



1 atom protoxide of iron, - - - 4*5 



14-5 



And this analysis has been repeatedly confirmed in my 

 laboratory ; while franklinite contains either no protoxide of 

 iron, or certainly very little : for the whole ferruginous con- 

 stituent of the mineral, is thrown down from the neutral muri- 

 atic acid solution, by benzoate of ammonia, which would not 

 be the case if protoxide of iron were present. Franklinite 

 seems to be a compound of, 



