HEAT PHENOMENA. 231 



mining works do not follow the lines of heat manifestation, but intersect 

 them in eveiy possible mannei'." 



Better data lately obtained. — Thanks to Mr. Churcli, better data have been ob- 

 tained since his memoir was written. At his suggestion frequent observa- 

 tions have been made on the temperature of the rock and the water 

 encountered in sinking the Combination, the Yellow Jacket, and the Forman 

 shafts. A long series of observations has also been made in the Sutra Tun- 

 nel, These observations and their discussion will be found in the second 

 section of this chapter. Though they might properly be introduced here 

 their voluminous character makes it more exjjedient to consider them sepa- 

 rately. The two chains of reasoning may be regarded as parallel argu- 

 ments on the same subject. 



Explanations of the heat. — VaHous cxplauatious liavc bceu offei'ed to account 

 for the prevalence of high temperatures on the Comstock. The source of 

 heat has been sought in friction, in the oxidation of pyrite, in the kaoliniza- 

 tion of feldspar, and in volcanic action. 



That heat must have resulted from the faulting action there can be no 

 doubt, but the whole tendency of the evidence is so strongly against the 

 application of Mr. Mallet's hypothesis of teiTestrial heat to this instance, 

 that a discussion seems unnecessary. The oxidation of pyrite, too, is a very 

 subordinate phenomenon on the Comstock. It is well known that vari- 

 ous occurrences of pyrite differ greatly in their behavior toward oxidizing 

 agents. That found on the Comstock is for the most part very stable, and 

 often remains exposed for years with no greater effect than tarnishing. 

 Most of the water from the Lode, too, shows but a small amount of sul- 

 phates. Indeed, there is much more reason to suppose that the formation 

 of pyrite is still in progress, on a small scale, than that the decomposition 

 of this mineral is the source of heat. 



statement of the kaoiinization hypothesis. — Thc hypothesis that the high* tempera- 

 ture is due to the kaoiinization of feldspar, appears to rest on two positive 

 grounds, viz., that flooded drifts have been observed to grow hotter, and that 

 the solidification of water liberates heat. In the argument supporting this 

 hypothesis, its author makes the following statement : 



"The direct evidence that heat is produced when water is brought in 



