334 Analysis of Argentine and Steatite. 



hard, and a small quantity of silex seems to enter into the 

 composition of the mineral. 



Heated to a temperature of 300° or 400°, it did not lose 

 weight. It gave no indications of even a trace of oxide of 

 manganese, which is sometimes found in argentine, and of 

 only a very small quantity of magnesia. At least, only a 

 minute quantity was separated from the lime by carbonate 

 of ammonia. 100 grs. of the mineral yielded, of 



Carbonic acid - - 41. grs. 



Lime - - - 54. 

 Silex - - - - 3.25 

 Magnesia and Oxide of Iron 0.75 



Loss 1.00 probably carb. acid. 



100,00 



If the the silex is to be considered an accidental ingredi- 

 ent, arising from the specimen being associated with quartz, 

 this argentine is a very pure carbonate of lime. 



Crystallized Steatite. 



Having ascertained that the mineral contained silex, 

 magnesia, alumine, water, and oxides of iron and manga- 

 nese, one hundred grains of a very large and fine crystal 

 were analyzed to ascertain the proportion of the ingredi- 

 ents. In the previous trials, the proportion of some of them 

 had been found, but as they were not much different from 

 those obtained from this crystal, it was judged proper to 

 rely on the results last obtained. In heating the mineral, 

 there was sometimes more and sometimes less than fifteen 

 per cent, of water liberated ; but the water is taken at fif- 

 teen per cent. In heating the mineral with sulphuric acid, 

 there was no indication of fluoric acid, which is sometimes 

 found in a variety of steatite. Indeed, the corrosion of the 

 glass vessel in which the experiment is performed, is some- 

 what equivocal, as sulphuric acid heated to 500° or 600° 

 will act upon the potash or soda in some kinds of glass at 

 least, and an actual corrosion take place. Oxalate of am- 

 monia gave no indication of lime. The method of analiz- 

 ing those magnesian minerals which are decomposed by 



