On the Native Sulphate ofAlumnia. 383 



blues to red, permanently. Muriate of barytes occasions a co- 

 pious precipitate in this solution. Ammonia gives a gelatinous 

 ■white precipitate, which, when collected on a filter, gradually 

 assumes a pinky hue. Prussiate of potash occasions a blue 

 precipitate. Muriate of platina occasions no change, and the 

 absence of potash or ammonia is thus ascertained. 



Analysis. 



1. Fifty grains of the whitest of the salt were dissolved in 

 distilled water, and the whole dissolved except 1.6 grain, which 

 consisted of sand and clay, extraneous substances, and not 

 therefore chemically combined with the mineral salt. 



2. This solution was treated with ammonia, and a gelatinous 

 precipitate obtained. 



3. This precipitate was collected on a filter and boiled with 

 a saturated solution of pure soda, when a portion remained 

 undissolved — this was collected, dried, and weighed 0.6 grain, 

 and was oxide of iron, the state in which it existed in the salt 

 being probably that of protoxide. 



4. The soda solution, No. 3, was then saturated with nitric 

 acid, and a gelatinous precipitate of alumine deposited, which, 

 when collected and exposed to a strong heat, weighed 7.5 grains. 



5. The liquid remaining from process 2, was then treated 

 with muriate of barytes, to obtain the quantity of sulphuric 

 acid in the salt; the precipitate obtained was sulphate of 

 barytes, which, after exposure to a strong red heat, weighed 

 42.4 grains, equivalent to 14.4 grains of sulphuric acid. 



6. If the salt contained no other ingredients, this liquid could 

 only contain muriate of ammonia, it was, therefore, evaporated 

 to dryness, and exposed to a strong heat, when the whole was 

 evaporated ; the salt, therefore, did not contain potash, soda, 

 era metal, except the iron before obtained, which was evidently 

 accidental. 



This new mineral, therefore, consists of 



Grains. 

 Extraneous substances, not soluble in water . . . 1.6 



Oxide of iron , , . . . ,0.6 



Alumina ....«• 7.5 



Sulphuric acid , . , « . . 14 .4 



Water 25^ 



60.0 

 2 C2 



