ANALYSIS OF ALUM ORES. ggfT 



but little action on the ore. On pouring nitric acid on it Nitric acid 

 drop by drop, nitrous gas was evolved, and the black co- ^'^'^^'*> 

 i^ur of the ore changed to brown. The filtered solution 

 was of a golden yellow; and muriate of barytes threw and muriate of 

 down from it a copious precipitate. This, which was sul- ^^^y^^^- 

 phate of barytes, being collected and heated red hot, weigh- 

 ed 54 grains. 



D. a. A thousand and two grains of the ore, not j^et Ore distilled, 



freed from the humidity it contains in the mine, were put S^^« ^^^ «"'- 



1 - - /• • 1 , . , phuretled and 



into a glass retort furnished with a pneumato-chemical ap- carburetted hi- 



paratus. Two hundred and twenty cubic inches of gas were ^'^"g'^n- 

 evolved, which was a mixture of sulphuretted hidrogcn gas 

 and carburetted hidrogen gas. If a candle were brought 

 into contact with it, it took fire, and burned with a blue 

 flame. When shaken in a vessel containing water, half of 

 it was absorbed. A solution of lead, poured into the wa- 

 ter impregnated with it, afforded a precipitate of a deep 

 brown, which was sulphuret of lead. 



b. The fluid that passed over weighed 133 grains. It was The fluid cou- 

 aqueous, yellowish, and turbid with slight flocks of sul- J^jj^^^ ammt-* 

 phuretted carbon. Its smell was that of sulphuretted am- nia. 

 monia, diluted with a great deal of water. Litmus paper, 



that had been reddened by an acid, it turned blue, and it 

 emitted a white vapour, on bringing near it a glass rod wet- 

 ted with fuming muriatic acid. A drop was let fall into a 

 solution of lead, and the metal was precipitated brown. It 

 was neutralized by a few drops of muriatic acid, and be- 

 came slightly milky. On being filtered and evaporated two 

 grains of sal ammoniac were obtained. 



c. The residuum left in the retort weighed 750 grains. Residuum con- 

 It had the appearance of a black coally powder. Being *^'"® ^"^ '^^' 

 burned on a test it left 90 grains, which were the carbon 

 consumed, 



d. The fifth part of the remaining 660 grains, or 132 Silex precipi- 

 grains, was roasted with twice its weight of caustic soda, portion of it. 

 The mass when cold was of a greenish brown, and gave a 



light green tinge to the water with which I mixed it. I su- 

 persaturated it with muriatic acid, evaporated, diluted it 

 again with water, and filtered. The silex was left behind. 

 ThiSjL after being heated red hot, weighed 80 grains. 



e. The 



