MEMOIR ON EMERY. 39 



IRON PYRITES. 



Pyrites is found principally with the emery of Gumuch and 

 Nicaria. At the latter locality it is in small crystals in the 

 interior of the mass. At Gumueh it is principally on the sur- 

 face, but much less abundant than at Nicaria. 



RUTILE. 



This oxide of titanium is found with the emery of G-umuch - 

 dagh and of Kulah, where I obtained some large detached 

 crystals. I have also a specimen with it in small crystals on 

 diaspore attached to emery from G-umuch -dagh. 



ILMENITE. 



It has been found on the gangue of the emery of Kulah in 

 minute crystals of the usual form of this mineral. 



TITANIEEROUS IRON. 



Titaniferous iron is found with almost all the varieties of 

 emery that I have examined, but I have analyzed none but 

 that associated with the emery of Nicaria. Care being first 

 taken to see that it was anhydrous, one gramme of it was 

 calcined in a current of oxygen and it augmented .019, which 

 indicated the presence of .171 gramme of protoxide of iron, 

 and corresponds to .190 gramme of peroxide of iron; the 

 same portion then decomposed by a current of hydrogen gas, 

 and the loss sustained was equal to .222 gramme of oxygen, 

 which corresponds to .740 gramme of peroxide of iron; de- 

 ducting from this the quantity of peroxide equal to the pro- 

 toxide (.171) contained in the mineral, we have .550 gramme 

 for the quantity of peroxide present. The mass reduced by 

 hydrogen was treated with hydrochloric acid, and the part not 

 dissolved (.230 gramme) was titanic acid with a little alumina. 

 The acid solution contained .010 lime and a trace of alumina. 

 The titanic acid was examined as to its purity and was found 

 to contain no silica and only a trace of alumina. The result 

 of the analysis is 



Protoxide of iron 17.10 



Peroxide of iron 55.00 



Titanic acid 23,01 



Lime 1.00 



Alumina a little, not estimated. 



