Geognosy of St. Paul's Buy. 79 



a tufaceoiis aspect, and is evidently not sulphur, neither is it 

 a carbonate, as it does not effervesce in acid. It is more pro- 

 bable that it is a sulphate of lime containing a small portion 

 of sulphur in a free state — the chemist, however, must 

 decide this. The first intimation the stranger receives of 

 being in the immediate vicinity of these springs is the 

 strong disagreeable smell of sulphuretted hydrogen, which 

 he liberally inhales, and if not satisfied with the proof 

 which his nose affords, he requires the further evidence of 

 his palate, the unwelcome flavour of spoilt eggs will 

 convince him of the presence of sulphur under its most 

 offensive form. 



Tl»e iron, or chalybeate waters are very abundant, and 

 are often found associated with the sulphuretted springs as 

 if they had had one common origin, which indeed is very 

 possible, as the decomposition of beds of iron pjTites would 

 afford them both. Whatever may be the origin of the 

 sulphuretted waters, liowever, we think that those con- 

 taining iron arc generally attributed to a partial solution 

 of the magnetic oxide of iron of the neighbourhood ; what 

 the solvent may be, (if any other solvent than water be 

 required,) we can only conjecture. Decaying vegetation 

 affords the phosphoric acid, and it is well worthy of reuuirk 

 that bog ore, whicii is evidently a precipitation from 

 waters holding iron in solution, always contains the 

 phosphate of iron. 



The astringent ink-like flavor of these waters is a suffi- 

 cient distinction to the taste, and when stagnant, or nearly 

 »o, a scum or a deposit of a red colour, which is in fact Ihc 

 rust of iron, marks their course. An iristd p<llich' floating 

 on the snrlace <»f such waters is also an indication of the 

 presence of iron. 



