^90 Mr Council on a Chalybeate Water. 



492.72 



And an imperial gallon contains,- 



3941.76 



There seems little doubt that this water proceeds from the 

 decomposition of some description of shale in the vicinity of its 

 site. Whether the shale in which it is actually found is capable 

 of affording its constituents by disintegration, I do not know, 

 not having yet obtained any specimens of it. Both proper 

 alum-slate, and various shales of the coal-formation, afford, as 

 is well known by decomposition, saline products appearing some- 

 times as solutions, and sometimes as crystallized salts.* 



• Dr Thomson has analyzed a chalybeate from the neighbourhood of Moffat, 

 somewhat analogous to the present in composition, although greatly inferior 

 in strength, and which he conceives to proceed from decomposed alum-slate 

 (Glasc. Med. Jour. i. 129). Its specific gravity was 1.00965. Its colour red. 

 In an imperial gallon it contained, 



Persesquisulphate of iron, . 591.025 



Sulphate of alumina, . . 112.756 



Sulphuric acid in excess, • . 5.202 



708.953 



The hair salt of the coal-strata of the neighbourhood of Glasgow was found 

 by Dr Thomson (Hist, of Chemistry, p. 104) to consist of, 



1 atom protosulphate of iron, 

 14 atoms sulphate of alumina, 

 15 atoms water. 



Constituting a kind of alum. Its solution in water would afford an alumi- 

 nous chalybeate, which by exposure to air would become more or less per- 

 oxidi^ed, unless the chemical union of the salts of iron and alumina should 

 prevent that process. 



