152 



GEOLOGY OF THE COMSTOOK LODE. 



Table 'J. — Silica determinations. 

 Dr. G. E. Moore, at my request, made the following tletermiuatioiis: 



Poiphyritic diorite, from the head of Ophir Ravine, much decom- 



po.sed, contains . . uS.aG per cent. SiOj 



Earlier diabase, tSntro Tunnel, 19,100 feet from entrance, highly 



decomposed, contains .jO.L'G i)er cent. SiOj 



Later diabase, Belcher 1,14.5, very fresh, contains 40.70 i)er cent. SiO^ 



Table 3. — Analysin of Water /nun the (JOOfoot Icrcl of the Saca(je mine, by rrofe.s.sor 8. 

 W. Johnson, of Yale Vollefie.' 



One liter contained — 



Grammes. 



Silica 0305 



Alumina and ferric oxide 0009 



Chloride of .sodium 0021 



Sulphate of lime 5044 



Sulphate of magnesia 0308 



Carbonate of potash 0148 



Carbonate of sothi 1297 



Carbonate of magnesia 5012 



.7044 



Table 4. — (Jaalitative determination of Comstoclc minctratcrs.'- 

 By EuGENK S. Bristol. 



» Exploration of the Fortieth Parallel, Vol. HI., p. 87. ^Exploratiou of the Fortieth Parallel, Vol. III., p. 

 3 In 100 cubic ceutimetora of water. 



