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Carnall estimates that 0.0008 per cent. of galena in this rock would 
suffice to supply the ore deposits. Such a minute quantity, it is argued, 
_ might well escape detection in the analysis of limestone; but, Hofer 
remarks, even the absence of the metals in the dolomites at present is 
no objection, since they have been already leached out. Althans thinks 
it highly probable that not only the dolomite but also the Upper 
Muschelkalk and Keuper beds, and even others lying higher contain 
diffused metals and were sources of supply to the ore deposits. But 
HO6fer thinks this improbable because of impervious beds in the Keuper 
and also at the base of the Upper Muschelkalk. 
In conclusion, Hofer sees no unanswerable objection to the expla- 
nation of the origin of the ores by descension and infiltration. 
The second alternative hypothesis was advanced by an anonymous 
G. W. in 1883. It resembles somewhat Chamberlin’s hypothesis 
applied to the Wisconsin ores, though the causes and conditions of 
original concentration are somewhat different and the degree of con- 
centration somewhat greater than Chamberlin requires. 
H6fer evidently favors this explanation, without distinctly saying 
so, but confines himself to the conservative statement that it deserves 
more consideration. Against Althan’s objection that such enormous 
metalliferous deposits could not be precipitated directly from sea 
water, he refers to the iron deposits of the southern shore of the Oberen 
Sea and to the Rammelsberg copper. deposits. .The sea,water of past 
ages can well have had, he argues, higher metalliferous contents, seeing 
that so much has now been .extracted..to form. our ore*bodies. The 
abundance of carbonaceous matter at the beginning of the dolo- 
mite formation would cause an excessive if not entire precipitation of 
the metal contents of the sea water. As the bituminous Vitriolletten 
became covered this would diminish. The dolomite being throughout 
somewhat bituminous a constant separation of metals in small quanti- 
ties probably continued, sufficient to impregnate the rock and to 
account for the scattered occurrences of ore found init. The alteration 
of the original deposits to their present forms must have taken place 
later, after oxidizing influences began to act. H6fer considers this 
hypothesis simpler, in that it does away with the necessity for the 
transportation by infiltration of metalliferous salts, and the whole open 
question of their solubilities is eliminated. 
After briefly reviewing similar ore deposits of other parts of Europe, 
our author concludes that they cannot be better explained than on the 
