Joseph LeConte—Genesis of Metalliferous Veins. 9 
well known are due wholly to peroxidation by contact with 
the air. Now there is here also a partial truth in Dr. Sand-, 
berger’s view, but not such as interferes with the view that 
which is only about 20-80 feet from surface ; but the 
deposit of these vein matters is not confined to this point nor 
determined only by this reaction, but takes place also far be- 
yond the influence of the atmosphere. What Dr. Sandberger 
has himself proposed as a test of this question, viz: deep ex- 
plorations beneath Sulphur Bank, has already been accom- 
plished and the question decided against him. In the ‘‘ wagon 
spring cut” the solfataric waters have been followed down far 
below the influence of oxidation and acidification to a region 
where the water is strongly charged with alkaline carbonates 
and alkaline sulphides with excess of CO, and H,S and the 
deposit of metallic sulphides is still abundant there. But what 
is still more conclusive, a shaft has been sunk to a depth of 
310 feet and horizontal drifts run at five different levels. 
