1 96 Intelligence and Miscellanies. 



In two trials also, which I made, one upon 14 grs. and the 

 other upon 20 grs. of the mineral, to learn if possible the ex- 

 act proportion of chrome it contained, (in one instance sepa- 

 rating it from its acid combination with potash, by the addi- 

 tion of muriate of barytes, and in the other by the proto- 

 nitrate of mercury,) 1 became satisfied from the smallness of 

 its proportion, which was such as to prevent my estimating 

 it by weight, that it did not form an essential ingredient in 

 the composition of the mineral. 



After these preliminary experiments, I entered upon the 

 following 



ANALYSIS. 



A. 17.8 grs. reduced to powder, were mingled with double 

 their weight of potash and 10 grs. of nitrate of potash. The 

 mixture was kept at a red heat in a silver crucible for one 

 hour. The calcined mass which had evidently undergone 

 fusion, presented a yellowish green color, which it commu- 

 nicated to its solution in water. On the addition of nitric 

 acid, the fused mineral became perfectly soluble, with the 

 exception of a few white flocculi of silex, which were seen 

 floating through the solution. 



B. The nitric solution was evaporated to dryness, in which 

 state it was kept at a heat of 212° for upwards of half an 

 hour, to ensure the complete decomposition of the nitrate of 

 iron and the separation of the silex. The dried mass, which 

 was reduced to the state of a powder, and frequently stirred, 

 assumed throughout a deep reddish brown color. Warm 

 water was now affused, and the oxide of iron and silex sepa- 

 rated by means of the double filter. 



C. This solution, (B.) reduced by evaporation to a con- 

 venient bulk, was boiled for upwards of an hour with an ex- 

 cess of carbonate of soda. The precipitate which ensued 

 was washed, dried and heated to ignition in a platina cruci- 

 ble for twenty minutes, after which -its weight was 5.5 grs. 

 Its color was pure white, and upon the addition of dilute 

 sulphuric acid it was wholly taken up, with the exception of 

 a iew flocculi of silex, whose weight it was not attempted to 

 ascertain. The solution was partially reduced by evapora- 

 tion, and set aside to crystallize. In two days, it shot into 

 crystals of Epsom salt. 



D. The insoluble oxide of iron and silex (B.) was heated to 

 redness in a close platina crucible over an alcoholic lamp, 



