208 EXAMINATIOIT OF THE OCHROITEff, 



ing in irregular, not very (harp or angular pieces. It is 

 perfe6tly opaque. Its powder is reddifli-gray. It is not very- 

 hard, but brittle, and very ponderous. 



Its fpecific gravity is 4,660. Cronftedt fiates it to be 

 = 4,988. 



A. 

 Analyfis of the a, A piece of the mineral after having been ignited im 

 ro'!:". rednefs, loft 2 per cent. Its reddifn colour had l?een changed 

 to brown. Its figure had fuffered no alteration. 



h. One hundred grains of the finely levigated mineral ig- 

 nited for half an hour, loft five grains. Its colour was 

 changed to a dark brown. 



B. 



a. One hundred grains of ochroit, after being mixt with 

 200 grains of carbonate of potafh, were ftrongly ignited, the 

 mafs which could not be rendered fluid, was reddifli, grey 

 and brittle. On being diffufed through water, as ufual, the 

 obtained folution was colourlefs. It remained perfectly tranf- 

 parent; a proof that it did not contain tungften oxide ; nitrate 

 of filver, mercury, lead, barytes, &c. proved the abfence of 

 acids. 



h. The infoluble refidue of the laft procefs was boiled in 

 nitro-muriatic acid, the liliceous earth being feparated, the 

 folution was decompofed by potafh, and the whole boiled for 

 fome time. The alkaline fluid after being neutralized with 

 muriatic acid, and then mingled with carbonate of potafh, 

 fufi^ered no change. 



C. 



a. 200 grains of the finely pulverized mineral, were firft 

 boiled in two ounces of muriatic acid, to which half an ounce 

 of nitric acid was gradually added, and the digeftion continued 

 for fome time. The whole became thus dilFolved except the 

 filex contained in the mineral. Its quantity amounted to 

 68 grains. 



b. To the folution obtained in the laft procefs, carbonate 

 of ammonia was added fo long, till no permanent precipitate 

 was produced. On letting fall into it fiiccinate of ammonia, 

 a curdiy precipitate fell^ which vaniflied again on agitation, 



leaving 



