540 J. B.. Kilroe — Latcrite and Bauxite in Germany. 



points in the Vogelsberg region, maj- formerly have been so copious 

 as to increase largely the proportion of this gas in the lower strata of 

 the atmosphere, when still, over the tracts where bauxite and laterite 

 are now found. Dr. Schottler believes that post-basalt faults traverse 

 the gi'ound north and south of Watzenborn, i.e. each side of the 

 rothen Hang bauxite tract. 



E. Kaiser, as well as Munster, rely upon carbonated waters to have 

 effected transformations of the German basalts,^ and Maclaren assumes, 

 and in part discusses, the reactions of C Oo in water in the solution of 

 silicates.^ In a preceding footnote I raise the question whether 

 spring water, either as a warm solvent or one acidified with C O3, can 

 penetrate throughout a superficial layer of rock or clay, as far as 

 would be necessary to suppose it effective ; and if this were doubtful 

 in a laj-er 50 feet deep, in proximity to the fault at Miicka, it would 

 seem much more doubtful east of Garbenteich, where the layer is 

 little more than a tenth of that depth. The circumstances of 

 distribution of the ores in both places strongly suggest that, if C O3 

 were the solvent, it must have been borne to the earth from an 

 atmosphere heavily charged with it, given off by fissure springs such 

 as those previously mentioned. 



It has naturally been questioned whether C Oo can be regarded as 

 an adequate solvent, and some observers have appealed to the action 

 of stronger acids. J. Walther, and especially Passarge,^ appealed to 

 nitric acid supplied by decaying rich tropical vegetation, and formed 

 during thunderstorms ; but this, in quantity at least, would seem 

 veiy inadequate. Others have favoured H^ S 0^^ and Hg 8 O3.* 8uch 

 acids, formed from pyrites (say) in the Vogelsberg 'Traps,' could 

 not affect the alumina, for in the weathered layer the amount of S O.5 

 would be immeasurably smaller than is requisite, even for the solution 

 of Mg and Ca, as may be seen by the following analyses. A is an 

 average of ten analyses of Trappgcsteine after Schottler, B and C are 

 analyses of bauxite and bauxitic clay given by Liebrich (p. 71) : — 



' Clarke, " Data of Geochemistry," p. 424. 



- Particularly if present in such strength as to produce intensive action (Geol. Mag., 

 1906, pp. 539-40). ^ " Petrogenesis, " p. 235. 



* Amongst the first to propose this was Professor G. A. Cole; see " The Rhj'olites 

 of the County of Antrim," p. 108. Clarke mentions the emanations from volcanoes, 

 as in Java, Sumatra, and Hawaii, op. cit., p. 425. See also G. C. du Bois and Bauer, 

 quoted by Doeiter, " Petrogenesis," p. 235 ; and Hayes and Liebrich, referred to by 

 Clarke, p. 421. 



