218 PROCEEDINGS OF THE ACADEMY OF 



Bemarks on Silver Ore from Colorado, by Geo. A. Konig. 

 I had an opportunity, lately, to test a silver ore from Coinload, 

 Colorado, and was astonished at the beautiful crimson and flesh- 

 eolored incrustation, which was obtained by treating the ore with 

 the point of the inner flame on charcoal. The crimson was most 

 intense in a zone immediately following the yellow incrustation of 

 lead, it went gradually through different shades of flesh-color into 

 the white incrustation produced by the teroxyd of antimony. 

 The ore was composed of Galena and antimoniferous ruby silver. 

 After a number of experiments with pure ruby silver from 

 Andreasberg, pure Galena, and pure sulphide of antimony, I found 

 that a crimson color could only be produced by the presence of all 

 three compounds, or an alloy of silver, lead, and antimony ; and that 

 it appeared only just before the silver button had become nearly 

 pure. Now, if we consider that silver alone, when kept in fusion 

 by a strong oxydizing flame, deposits a brown coating in the 

 immediate neighborhood of the button, that lead produces an 

 incrustation of plumbic oxyd, which is of a dark yellow color 

 while hot and a lighter yellow in the cold, and lastly, that antimony 

 gives rise to a copious white coating, at some distance from the 

 flame, of antimoni teroxyd, it seems striking that the three 

 metals together should produce a crimson incrustation. A 

 mechanical mixture of the three oxyds brown, yellow, and white, 

 cannot be supposed to bring about a crimson color. Also the 

 fact, that only then this color appears, when the silver is nearly 

 pure is suggestive of a peculiar chemical combination, formed of 

 the oxydized metals as soon as these are brought into a certain 

 quantitative relation. 



At the same time it must be inferred that the volatility of silver 

 is increased to a considerable amount when this quantitative rela- 

 tion is reached. This latter reflection might throw, perhaps, some 

 light upon the inaccurac}' of the cupelling assay in certain dases, 

 where the loss of silver is larger than usually. 



It seems to me of some interest to investigate into the nature 

 of this crimson-colored compound, and I hope to be able to lay 

 before the Academy some positive results regarding it, at an early 

 date. The observation of crimson-colored incrustations from 

 silver ores containing lead and antimony is not new. Prof. Richter 

 mentions them in the last edition of "Flattner's Probirkunst 

 vor dem Loethrohr," Leipzig, 1865, page 84. But as to the real 

 cause, there has no publication been made, so far as my knowledge 



goes. 



The death of Samuel Emlen Randolph was announced, 



December 17. 

 Dr. J. L. LeConte in the chair. 

 Nineteen members present. 



