PEEVIOUS INVESTIGATIONS. 31 



been preserv-ed from cnisliing. It was formed in the state of jjowder, and 

 since its dejDOsition the Lode rocks have not received any addition which 

 could weigh it down. On the other hand, the barren quartz was probably 

 laid down in a similar state of powder, and has been consolidated by the 

 load of trachyte upon the surface." 



The heat of the Lode Mr. Church ascribes to the kaolinization of feld- 

 spar, supporting this view by the statement, that as kaolinization involves 

 hydration, heat must be liberated, and by the assertion that flooded drifts 

 grow hotter. He believes the heat to be diffused by hot aqueous vapor 

 permeating the rocks. The latter, he asserts, are in large part perfectly dry. 



Technical literature. — Though most of the scicntific and technical journals 

 contain papers on the Comstock, or items i-eferring to it, and much space is 

 occupied by the same subject in the reports of the United States Mining 

 Commissioners and of the State Mineralogist of Nevada, I am not aware 

 of any further noteworthy contributions to its geology. The numerous 

 geological suggestions thrown out by engineers writing from a more or less 

 technical point of view, were never intended as matured geological opinions, 

 and it would be unfair to treat them as such. 



