16 Dr. Genth’s Contributions to Mineralogy. 
probably from the same place, but may be from Whitehall Mine, 
potsylvania county, Va. 
Though I was most careful in selecting the material for this 
investigation, I found invariably from one half to two per cent. 
of quartz, gold and oxyd of iron mixed with it, which were de- 
ducted as impurites. 
In making the investigation I have found the method hereto- 
fore used for the separation of bismuth from tellurium, by sul- 
phid of ammonium, not to be as correct as is desirable, since 
there is always a considerable amount of tellurium remaining 
with the bismuth ; I therefore tried to find another m | 
would give more satisfactory results, and succeeded best with the 
following: The solution containing teroxyd of bismuth and 
tellurous acid was made acid by hydrochloric acid, sir to the 
hot solution bisulphite of ammonia was added. It was allowed 
to stand in a warm place for a day or two until all the. nlicaiena 
had settled ; this was filtered on a weighed filter, washed first 
with a mixture of diluted hydrochloric and sulphurous acids, then 
with sulphurous acid alone, and finally with water. 
lurium was completely precipitated and did not contain a weigh- 
able quantity of bismuth. The results of the analyses I. and IL 
afterwards corrected, and III. and IV. analyzed by this 
method. B.B. it fuses readily giving out a faint but distinct 
odor of selenium, leaving on charcoal white fe ern with 
a yellow centre. The sabetaed results were obtained : 
i IV. 
Calculated. 
coh cee Bete 
From Tellurium Mine. ? From Whitehall Mine. 
Bismuth, 5307 53°78 51:56 Not determ. 1 igh Leer 
Tellori 48°19 A707 49°79 46°10 
Selenium, traces : 
Sulphur, none none none 037 
These analyses show that neither of the specimens contained a 
weighable amount of selenium. The small quantity of sulphur 
(in No. IV,) 0°37 percct. is equivalent to 1-48 per ct. of tellurium, 
which if we substitute tellurium for pst would give 47°53 
per ct. of tellurium. These analyses show that Tetradymite is 
tertellurid of bismuth, but that pe imciored Fees I showed for that 
from Davidson county) a variable quantity of tellurium may be 
replaced by sulphur. I have also observed that Tetradymite oc- _ 
curs at several localities in Cabarrus county, N. C., where I have 
found it in minute lead-colored scales, associated with gold and 
iron te in quartz at the Phoenix Mine and at the Boger Mine ; 
but, » I had sufficient material to determine the nature of 
the sale, I could not obtain enough for a quantitative oars 
6. Bismuthine. 
tL tril Dacrean on ae Tt 
1 foand pte oeeee ai speeimens from the Barnhardt vein 
me 
