292 Analysis of the l^eleninrets of the Easlethi Harz. [Oct. 



Selenium 24*97 



Lead Z .aJiwrH^ 55-84 



Mercury... ..,.., *..•»•..... 16*94 



I^ss.?^vi\j:>u>>tvJ^,Wvtt^^i'J.^u^j;)X 2*25 



iOtl flSilBi 91C ^I'xJnmj DniwoHd) ^dl x^noiicp. 100*00 - H 



The loss IS too great to allow us aceurateiy to determine the 

 composition of the mineral, lut I have reason to believe that it 

 consisted principally of selenium. 65*84 of lead combine with 

 21*39 of selenium, and 16*94 of mercury with 6*63 of selenium. 

 \Ve may, perhaps, imagine it to consist of an atom of sreleniuret 

 of mercury and three atoms of seleniuret of lead. 



I am satisfied, however, that the seleniuret of lead in this 

 mineral is not combined with the seleniuret of mercury in any 

 definite proportion, but that the two seleniurets are capable of 

 uniting (like isomorphous substances) in all proportions without 

 affecting the form of the compound; for I treated 0*9 gramme 

 (13*9 grains) of the same specimen from which I selected the 

 portion for the first analysis with chlorine, carefully selecting 

 the cubic pieces which had precisely the same external appear- 

 ance as those which I had analysed in the first instance, and I 

 obtained only 033 gramme (5 grains) of chloride of lead, equi- 

 valent to 0*246 gramme (3-8 grains) of lead. If we calculate the 

 composition of the mineral according to this result, we obtain 

 the ibllowing as the proportions of its elements, wholly difierent 

 from the other. ] • > r 



Selenium '^,.,^ . . . i 1 27-9S'""""' 





T^ead . ',. *j*i,««Kkr.*j; . • • 4 •u^-4 • » • • 27*33 



Mercury. . .a4i*.*.i . . . j .ri^ ».4 44*69.,07£,^rf 



In addition to the "pfecedin^ tnineralg, M. Zinken has also 



sent me another containing selenium, lead, copper, and a good 



deal of silver. I have not, however, submitted it to a qttantita- 



.tive analysis, because the specimen was mixed not only with 



,.magnesian spar, but also with copper pyrites, from which I 



^ could not separate it. The copper pyrites moreover covered the 



whole mass in the form of raainmella;, and contained^ itself, a 



large portion of sjelcuium. 



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