10 



when it should go north and vice versa, concludes at once that it 

 is not worth following up, as it can only be an offshoot which will 

 end abruptly. 



The discovery in these veins, too, of organic remains by Mr.. 

 Moore, renders it still more difficult to connect their formation 

 with volcanic action, and the alternative then forced upon us of 

 believing that the metals were deposited from an aqueous solution, 

 gains considerable support from the observations of M. Laur, who 

 finds that hi California, quartz veins containing gold in a native 

 state, and copper, iron and other metals as ores, are now being 

 deposited by hot siliceous springs. 



When the shock of an earthquake was felt at Bath some little 

 time back, several timid people believing the hot springs to be due 

 to volcanic action, were afraid of a volcanic eruption, and I believe 

 Sir Charles Lyell has lent some countenance to this notion of the 

 source of the heat of our springs. For my own part I cannot but 

 think with those who believe that the evidence is very much in 

 favour of chemical rather than of volcanic action. The Bristol 

 springs, which rise at a temperature of 76° F., probably owe their 

 heat to the oxidation of the iron in the conglomerate beds, and it is 

 possible the Bath springs, though at a great depth, do too ; at any 

 rate, if they do not, the abundance of iron pyrites in the lower lias 

 beds, under the process of oxidation, will more than account for the 

 high temperature. It has been strangely objected that if the heat 

 were due to chemical action, it would be intermittent and irregular, 

 whereas the direct contrary is the fact, and the objection would tell 

 with twofold force against volcanic action, which is in its very 

 nature intermittent. Rain in falling through the atmosphere 

 dissolves an appreciable amount of oxygen, and as the water 

 percolates through the different strata until it arrives at the store- 

 house from whence the spring takes it rise, the dissolved oxygen 

 would combine energetically with the sulphide of iron (iron 

 pyrites) with which it comes in contact in its downward course, and 

 the combination would cause a large amount of heat. Each gallon 

 of rahi water would, as it were, carry down with it sufficient fuel to 

 raise it to a given heat, and as the quantity of oxygen it holds in 

 solution is practically always constant, so would the heat of 



