Koenig.] ^J--^ [Jan. 16, 



quence, and one-half gram only was used for each analysis. Of one analy- 

 sis all but the lead determination was lost. 



After separating Pb and Bi by dilute sulphuric acid and weighing 

 the first as PbSO^, the latter was dissolved in NaHO, and if a residue 

 remained, it was dissolved in NHO3 evaporated with dil. H2SO4, and thus 

 a complete separation of Bi and Pb effected. Bi was weighed as BiClO. 



The spec, gravity of 1.014 gr. was found = 6.783. 



The analysis gave 



+ 12.16) 



99.16 

 If we deduct again 0.84 Fe -f 0.95 Cu -{- 0.94 S as chalcopyrite, we 

 have as belonging to the light gray mineral : 



0.3543 



[- 0.1317 



0.5330 



that is (Pb. CU2, Ag2. Zn) S + Bi^ S3 =: Alaskaite. 



If the zinc be left out of the molecule, the ratio of 1 : 2 is perfect. It 

 may be presumed therefore that the alaskaite is certainly a valid species, 

 and that it occurs with cosalite at the Alaska mine. From the latter spe- 

 cies only the lighter gray color distinguishes it, but one must see the two 

 together to notice the difference. The discovery of the cosalite at this 

 mine we owe to Dr. Genth. 



Among the specimens, which I received through Mr. Stockder of Lake 

 City, from the "Old Lout" I noticed a very fine granular lead gray 

 mineral which appears mixed with pyrite, chalcopyrite, barite and quartz. 

 I succeeded in getting 1.11 gr. of it in a very fair degree of purity. Its spe- 

 cific gravity, uncorrected, is 6.565. Its composition as follows : 



95.72 



