S68 ANALYSIS OF ALUAi ORES, 



Alumine. c. The solution that had passed through the filter 1 pfe* 



cipitated by carbonate of potash, washed the precipitate, 

 and boiled it in a lixivium of potash, which became loaded 

 with alumine. This earth being precipitated by muriate of 

 ammonia, washed, and heated red hot, weighed 32 grains. 



Sulphate of y. The brown residuum, that remained in the alkaline 



lixivium, was dissolved in sulphuric acid, and evaporated 

 to dryness. During the evaporation sulphate of lime was 

 deposited, which, carefully collected, weighed two grains. 

 The dry mass was strongly roasted, and then lixiviated^ 



Oxide of iron. The oxide of iron, collected on the filter, was dried, moist- 

 ened with a little oil, and heated red hot in a close vessel, 

 when it yielded 14*5 grains of oxide of iron attractable by 



JNfagnesia. the magnet. The remaining liquor, decomposed during 



ebullition by carbonate of potash, gave some slight indi- 

 cations of carbonate of magnesia. 



Waterexpelled E. «. One hundred grains* were put into a small glass 



jy eat. retort, which was placed on a sand heat, and the fire cau- 



tiously increased, lest any gas should be evolved, or any 

 perceptible decomposition occasioned, and that nothing but 

 water might be raised from it. The quantity expelled was 

 21 "5 grains. It had a very slight opal tinge, and a very 

 faint smell of sulphuretted hidrogen. A very slight coating 

 of sulphur too was deposited in the neck of the retort. 



The ore burned ^' The ore being dried was burned on a test; when the 



without flame combustion proceeded without flame or smoke, and emitted 

 but a slight sulphurous smell. - The loss in weight, which 

 was 45 grains, represents the quantity of sulphur and char- 

 coal burned, and perhaps too a small portion of water, 

 that was left in the ore. 



Magnesia preci- ''• ^he residuum was dissolved in a mixture of 200 grains 



pitated, of sulphuric acid, and 400 of water, evaporated to dry- 



ness, and kept at a strong red heat for half an hour. The 

 residuum was lixiviated, filtered, and precipitated with ara- 

 ijoouia, when 0-5 of a grain of magnesia were obtained. 



* This is apparently an errour of the press. According to the 

 proportions of the constituent principles given at the end, it must 

 ha\e been two hundred grains. F. Ed. 



d. The 



