Mineralogy and Geology. 283 



a thorough analysis in the laboratory of Prof. J. C. Booth. I subjoin a 

 description and the analysis. 



Description. — Foliated, without any appearance of regular crystalli- 

 zation, the laminse not elastic. Color between lead gray and steel 

 gray ; lustre metallic shining; H.=2; sectile; soils paper slightly. 



On charcoal it fuses readily, tinging the flame blue, forms a white 

 coating tinted red on the edge, and gives the odor of selenium. In 

 an open tube, it fuses emitting the odor of selenium, forming a red 

 sublimate of the same, and gives off white fumes, while a fusible yel- 

 lowish white sublimate of tellurous acid is formed, the residue being 

 brownish while. 



Analysis. — It was dissolved in nitro-muriatic acid, evaporated to 

 expel the nitric acid, partially neutralized by ammonia, and precipitated 

 by an excess of sulphydrate of ammonium, with which it was digest- 

 ed to dissolve the tellurium. The latter was determined by solution in 

 acid, and precipitation by sulphurous acid, which was repeated in order 

 to obtain all the tellurium. To separate the selenium from the tellu- 

 rium, the metal was treated with nitric acid, fused with carbonate of 

 soda and saltpeter, again treated with an excess of nitric acid and 

 precipitated by nitrate of baryta, which throws down seleniate of ba- 

 ryta, insoluble in a nitric solution. The metal can be perfectly isola- 

 ted, and presented in the metallic state by means of sulphurous acid. 

 The bismuth and iron were separated by sulphuretted hydrogen, and 

 the former determined as oxyd. The silica contained traces of tin, 

 and a minute trace of gold. The following are the results of the anal- 

 ysis of 19-96 grains. ° 



In 100 parts. 



Bismuth, . . 10-31 51-65 5481 



Tellurium, . .714 3577 37*96 



Selenium, i . 1-36 6-81 7-23 



Iron, . . , 025 125 . . 



Silica, . . 0-77 3-86 . . 



19-83 9934 10000 



The iron and silica being thrown offas impurities ; the per-centage cal- 

 culation of bismuth, tellurium, and selenium, are contained in the third 

 column. Assuming the oxyd of bismuth as Bi 3 , when the equiva- 

 lent of Bi is "213, it is evident that we have a tertelluret of bismuth 

 Bi Te 3 , in which a portion of the tellurium is replaced by selenium; 

 for regarded as Bi Te„, the 37-96 of tellurium requires 42-11 bismuth, 

 and 7-23 selenium requires 12 83 bismuth; and 42 11+ 12-83=54*94 

 bismuth, which is almost precisely the amount found by analysis. The 

 mineral is therefore similar to "the telluret (Telradymite) found in 

 Hungary, but is a telluret and selenuref, instead of being a telluret and 

 sulphuret. Its approximate formula is Bi Se 3 +3 (Bi Te 3 ) ; or putting 

 the selenium and tellurium together the formula is Bi Te 3 . 



2. Emery Formation of Asia Minor; by J. Lawrence Smith.— The 

 following communication, received in a letter from Dr. Smith, dated 

 Consiantinople, January 5, 1849, is a translation of a communication 

 addressed by him to Elie de Beaumont. 



