I 



21 



With regard to the peroxide of iron, it became an interesting subject of in- 

 quiry : — By what acid was it originally held in solution, before it was deposited 

 in this interesting formation ? Could it be nitric, hydro-chloric, or sulphuric, or 

 was it originally dissolved by the aid of carbonic ? The absence of nitrogen, and 

 the very small portion of chlorine and sulphuric acid (merely a trace), compared 

 with the abundance of base, at once determine that the first three acids could not 

 have been the solvents, and there was every reason for the supposition that carbonic 

 acid was ; but by reasoning from analogy, and considering that where iron was 

 held in solution by this acid as in chalybeate springs, its instant exposure to the 

 atmosphere deprived it of the carbonic acid, producing a deposit of peroxide of 

 iron — this, I admit, would be a fatal objection to this theory, provided that we 

 could prove the constitution of the atmosphere, during the existence of those 

 early seas, was the same as it is at present. The constitution of our atmosphere 

 apart from carbonic acid and aqueous vapour is — 



71 oxygen, and 21 nitrogen ; or 



77 "50 nitrogen gas, 



21 "00 oxygen, 



1'42 aqueous vapour, 



0'08 carbonic acid. 



Although there is a constant quantity of carbonic acid evolving from decaying 

 vegetable matter, yet the quantity of the different elements of which atmos- 

 pheric air is composed varies but little on any part of the globe. But geologists 

 consider (and indeed with great plausibility) that the atmosphere which surrounded 

 our globe before the Carboniferous era, must have contained a much greater pro- 

 portion of carbonic acid than it does at present, so much so, as to be incapable of 

 supporting animal life, except that of the lowest scale ; and instead of abstracting 

 carbonic acid, the atmosphere was one of the greatest sources of its supply. The 

 growth and development of the vast forests (which afterwards became submerged, 

 and by the influence of heat and pressure became our present extensive coal fields, 

 which is in reality, the basis of our national wealth, for without our coal fields our 

 steam engines would be powerless — our railways could not exist — our iron works 

 would languish — our cotton factories would never have attained to their present 

 position, and all our other great manufacturing speculations of wool, flax, silk, 

 &c., would be in weakness and decay) were the cause of the abstraction of the 

 super-abundant carbonic acid from our atmosphere, and subsequently fitted it 

 for the use of every class of air-breathing animals. That carbonic acid does hold 

 in solution peroxide of iron, we have abundant proof, in the chalybeate springs found 

 in various parts of tliis island, and, indeed, in our own county. I analysed, some 

 years ago, a spring of this sort, belonging to the late Mr, Bumham Pateshall, of 

 Allensmore ; it contained a quantity of iron, held in solution by carbonic acid, 

 together with lime and magnesia. I have also found it in water passing through 

 a meadow belonging to Mrs. Powell, situated near the road leading from Hereford 

 to Eoss, about a mile and a half from Hereford, and doubtless it occurs in many 

 other parts. This fact has been doubted ; but to me, considering the nature of the 

 substance, it is rather a wonder that chalybeate springs are not more frequently 

 found. Mr. Hugh Miller, in his work entitled " The Old Red Sandstone," in relating 



