476 
On Mineral Waters . 
bably also with sulphuret of potash. From the experiments ot 
Higgins and Kirwan, we know that alkaline and calcareous sul- 
phurets are useful in bleaching. 
Tincture of galls, and triple prussiat of potash, produced no 
change ; it therefore contains no iron. 
Oxalate of ammonia, hardly afforded a perceptible cloudiness. 
It therefore contains but little lime. 
Carbonat of potash, threw down no magnesia : nor did carbo- 
nat of ammonia throw down any alumine, or the addition of plios- 
phat of soda, exhibit any magnesia. 
Nitrat of silver occasioned no precipitate ; hence the water con- 
tains no muriatic salts. 
Acetite of lead, produced a precipitate tinged blackish : indi- 
cating a sulphuret of potash or of lime. 
Muriat of barytes detected no vitriolic acid combined or un- 
combined. The colour of litmus-rag, was not changed either blue 
or red ; so that there appeared to be no uncombined acid or alkali : 
A pint of the water gently evaporated to perfect dryness, in a 
queens- ware basin, by means of a spirit lamp, yielded barely 2 and 
^ grains of deliquescent residuum ; which was half potash and 
half lime, both manifestly distinguishable to the taste, as well 
as by tests. This was repeated in Florence flasks, with the same 
results. These salts had doubtless been combined with sulphur. 
Hence, the water in question, is water more pure than common, 
in every respect, except in holding half its bulk or there about of 
sulphuretted hydrogen gas, to which alone its medicinal properties 
are owing ; for the very small proportion of alkalies and lime com- 
bined as sulphurets with the sulphuretted hydrogen water, cannot 
be regarded as producing much effect. The weather had been 
rather wet for about a week or fortnight preceding the time when 
the water was taken up ; but there had been no rain for 3 or 4 days ; 
nor did it seem, that the water was either more or less abundant 
than usual. So that the preceding experiments may be considered 
as made on the water, in its average state. 
I conjecture, that the sulphuretted hydrogen, is produced by 
the decomposition of pyrites, deposited in the shale forming the 
roof of a coal stratum ; though no trace of coal has hitherto been 
found or suspected in that neighbourhood. . In many counties 
of England, the pyrites found in the roof of coal and the super- 
incumbent stratum, is collected, placed in heaps exposed to the* 
