366 ANALYSIS OF ALUM ORES. 



Half the solu- h. Half of this was (lecomposed by a solution of muriate 

 s'^^bjTmuriate ^^ barytes, and sulphate of barytes was formed, which, 

 of barytes, after being heated red hot, weighed 23 grains. This pre- 

 cipitate being separated from the liquor, prussiate of am- 

 monia threw down another of prussiate of iron, weighing 

 40 grains, 

 the other half c. To the other half oxalate of ammonia was added. It 



by oxalate of became a little turbid, and assumed a pale yellow colour, 



ammoaia. ... , , , ' ,. . „ . \ 



which probably arose from a small quantity of oxalate of 



iron. It then gradually grew clear again, a precipitate 



falling down, M'hich, after having been heated red hot, 



weighed 2-5 grains, and was found to be lime contaminated 



with iron. 



Proportions of Thus what the ore had yielded to the water, in which it 



the sulphates of jj^(^ IjggjjtjQ-jgj consisted of sulphate of lime and sulphate 

 hme and iron 7 r- r 



determiaed. of iron, the proportions of which may be determined as 

 follows. A thousand parts of ore produced 46 parts of 

 sulphate of barytes, which contain 15*18 parts of concrete 

 sulphuric acid. Of these 7 parts are required to neutral- 

 ize the 5 parts of lime; and thus, including the water of 

 crystallization, we may admit 15 parts of gypsum, or sul- 

 phate of lime, in the ore. The 8' 18 remaining parts of 

 sulphuric acid with 8-5 parts of iron will give about 18 

 parts of vitriol of iron at the state of decomposition. 

 The ore boiled B. Two hundred grains of ore, and 400 grains of dry 

 with carbonate carbonate of soda, were put into water, and boiled. The 

 of soda and pre- ^ ^ t . 1 i 



cipitated by liquor when filtered was of a very deep blackish brown co- 

 munaticacid. Jour. Muriatic acid was gradually poured in, which af- 

 forded no indication of sulphuretted hidrogen gas; but a 

 muddy sediment was formed, of a blackish brown colour, 

 and occupying considerable space, which, when collected 

 on a filter and dried, weighed twelve grains. Heated in a 

 platina crucible, it burned, without emitting any sensible 

 smell of sulphur, and left behind one grain of white alu- 

 mine. 

 Ore digested in C. Two hundred grains were digested in muriatic acid. 

 munatic acid, rpj^^ slightest indication of sulphuretted hidrogen gas was 

 not observable, either by the smell, or by holding against 

 ^ the mouth of the vessel paper, on which I had written with 



solution of acetate of lead. The acid appeared to display 



but 



