20 SIXTH REPORT — 1836. 



been detected in the following springs amongst others, viz. 

 the chalybeate of Hofgeismar by Wurzer, that of Pyrmont by 

 Brandes, and that of Selters by Gustavus Bischoif ; and the 

 latter principle at Carlsbad, Selters, Ems, Wiesbaden, and 

 Gastein. 



Now though phosphoric acid is not generally stated as a con- 

 stituent of the rocks through which these springs have to pass, 

 yet I am incUned to believe, that it exists in minute proportions 

 in very many of those that contain organic remains. 



I have myself found traces of it in several secondary lime- 

 stones ; and its existence there may be ascribed, not merely to 

 the coprolites which these strata sometimes envelop, and which 

 are found more or less in formations, even as high in the series 

 as the Silurian rocks of this country, but likewise to the bones 

 of animals, the coverings of Crustacea, and the scales of fishes * 

 distributed through them. 



In granitic rocks its presence is equally implied by the occur- 

 rence of minerals in which it constitutes the acidifying principle. 



The fluoric acid exists in the teeth of animals, but it would 

 be absurd to attribute an organic source to its presence in the 

 strata. Its origin must be looked for in the minerals which the 

 primarj^ crystalline rocks contain. Thus mica and amphibole 

 have been shoAvn by Bonsdorff often to contiiin small portions 

 of this acidf, and fluate of lime is to be met with occasionally 

 both in primary and secondary formations. 

 Carbonate There is a class of springs, very common in some countries, 

 of Soda, thougli scarcely found in England, which owes its peculiar pi'O- 

 perties to the presence of a portion of soda, often associated 

 with protoxide of iron, both of which are held in combination 

 b}' carbonic acid. 



Now as carbonate of soda does not exist in any of the strata 

 with which we are acquainted, its occurrence cannot be so im- 

 mediately referred to the latter ; and j-et the quantity drawn from 

 the bowels of the earth by the agency of springs must be very 

 considerable, for Gilbert X calculates, that the water given out 

 in a single year by the Carlsbad waters alone contains more 

 than thirteen million pounds of carbonate of soda, and about 

 twenty million pounds of its sulphate, so that Me may fairly 

 reckon the annual amount of alkali extracted, under one or the 

 other of these forms, to be as much as 6,746,050 pounds. 



• See Notice of Mr. Connell's Paper in the Fifth Report of the British As- 

 sociation, p. 41. 



t Edinlmrt/h Philosophical Journal, vol. iv. 

 J Amialen, vol. Ixxiv. p. 198. 



i 



