GEOLOGICAL SOCIETY 



35 



muriate of barytes, a dense, copious white precipitate 

 occurred. From this it was concluded that the salts 

 obtained from the earth, contained the sulphuric acid, 

 united to the peroxide of iron, forming, probably, the 

 sesquisulphate of the sesquioxide, the formula of which 

 is in modern chemistry— §(Fe + 3S) 



5. On throwing a coil of iron wire into the solution 

 of the salts, the red or peroxide of iron was precipitated 

 from it in abundance ; the sulphuric acid united to the 

 wire, and hydrogen gas escaped. The color of the 

 solution passed at the same time from its clear original 

 brown tint to a bright green. On evaporating this so- 

 lution, light green crystals appeared, which were found 

 to be copperas, or the sulphate of the protoxide of iron, 

 represented by Fe+ S. A dark brownish earthy sub- 

 stance which would not crystallize remained in the 

 liquid. 



6. Supposing that alumine formed an ingredient in 

 the salts washed out from the earth, we added an alco- 

 holic solution of pure potash to the dried red precipi- 

 tate produced in the last experiment, (5th.) This solu- 

 tion was then filtered and treated with sulphuric acid. 

 No precipitate took place, not a particle of alum, or 

 sulphate of potassaand alumina ( Al + 3 5 ) + ( Po + 8 )24 aq. 

 could be discovered. On evaporation, a yellow ferru- 

 ginous mass was obtained, intermixed with some trans- 

 parent crystalline needles., which had the bitter saline 

 taste of the sulphate of potassa ; the sweetish astringent 

 taste of alum was altogether wanting. 



From these experiments we conclude that there is no 



