138 SILVEK-LEAD DEPOSITS OF EUKEKA, NEVADA. 



gold. The residue was dissolved in nitric acid and filtered. The gold pre- 

 cipitated was treated with hot nitric acid to remove any oxalate of lead 

 present; filtered, and this nitric acid solution was added to the first nitric 

 acid solution obtained, and the whole evaporated to a small bulk, about 1 

 c. c. This was divided into two portions. One was tested with diluted 

 sulphuric acid and the insoluble sulphate of lead was obtained ; the second 

 portion was tested with potassic chromate, when chromate of lead was pre- 

 cipitated and crystallized by boiling. The whole of the lead was then con- 

 verted into sulphate and weighed. The weight was 0.0033 grammes. That 

 there might be no question as to the character of the compound, the sul- 

 phate was finally reduced to metallic lead. The 0.0033 grammes (0.00825 

 per cent.) do not represent all the lead that was probably contained in the 

 porphyry, as there was no doubt some loss, but the result is sufficiently accu- 

 rate to establish the fact that this rock, although considerably metamor- 

 phosed, contained appreciable amounts of lead as well as gold and silver. 

 As the assay value of the porphyry in silver was 6 cents (0.0001591 per 

 cent.), there was about 52 times as much lead present as silver. 



