Chemical Observations upon Spathic Iron. 251 



wards evaporating to dryness, and in redissolving with water 

 the salts which were not decomposed. The oxide of iron 

 was collected upon the filter. I afterwards precipitated the 

 mancranese with the prussiate of potash ; and I obtained, 

 wittfthe assistance of a fixed alkali, the earthy substances 

 contained in the clear liquor. Last of all, I separated the 

 lime from the magnesia by means of sulphuric acid and eva- 

 poration. It is to be observed that the nitric solution must 

 not be evaporated too strongly : without this precaution we 

 run the risk of decomposing a great portion of the nitrate 

 of manganese. I examined, by several methods, the pro- 

 ducts of each experiment, in order to avoid errors as much 



as possible. 



I subjoin an account of the products obtained from each 



analysis. Vaunaveys. Allevard. 



Fragments of quartz O 



Red oxide of iron 



Red oxide of manganese 



Magnesia 



Lime 



Loss by calcination 



Excess 8 Loss I'A 



These results do not indicate the exact proportions of car- 

 bonic acid which exist in these spathic irons, because one 

 part of this acid is decomposed during calcination, and there 

 results from it a much stronger oxidation of the metal, in 

 c U ch a manner that the loss which the ore goffers, and 

 which might be ascribed to water and carbonic, acid, is a 

 IHtle below the real quantity in relation to this last princi- 

 ple ; but u, on the other hand, the iron in the ore is in the 

 state of a green oxide, and as I have obtained it in the state 

 of red oxide, ihe augmentation which results from it com- 

 pensates for the low estimate of the carbonic acid ; and in 

 the last result the rial loss is a mere trifle. 

 ■ continued.] 



XXXIX. Da- 



