, , and on the Isomeric Modifications of Selenium. 505 



sited along with all the metals precipitable by zinc, and mixed 

 besides with those which the zinc itself contains. It is better 

 to effect this precipitation by sulphurous acid gas ; the pulveru- 

 lent tellurium is then melted in a crucible to a regulas. 



In order to obtain chemically pure tellurium, it is necessary 

 to distil the tellurium precipitated by sulphurous acid in a stream 

 of hydrogen. It is then melted in a crucible. Tellurium forms 

 thus a regulus of a metallic lustre, which is the whiter the purer 

 it is, and presents on its surface crystalline ramifications in 

 the sbape of fern leaves, like those exhibited by antimony. Its 

 specific gravity, according to M. Lowe, is 6*18. 



I made expeiiments, first on tellurium simply precipitated by 

 sulphurous acid, and then on that distilled in a current of hy- 



drogen. 



Tellurium not distilled. 



Mean 0-05160 (which is identical with that which I found in 

 my former experiments). 



The product of the specific heat by the atomic weight 806*5 

 is 41-65. ^ .^ 



Distilled Tellurium, ^''* ' 



M . . . . 148^^-15 148^'--] 5 



T .... 98°-28 98^-33 



^ . . . . 17°-88 18°-92 



A^ I' :^^, . i°-3384 1°-3191 



A T "^''^ . 422^^-54 422^'--54 



.... 0-04748 0-04727 .'« "' 



Mean .... 0-04737. ' 



The product of this specific heat by the atomic weight is 38*20. 

 The latter result ought to be received ; we see that it is com- 

 prised within the limits of variation observed in very jpure simple 



Selemum, 



I formerly determined the specific heat of selenium by uniting 

 the specimens which were then to be found in the various col- 

 lections in Paris. The substance was in the form of small pen- 

 cils, or of medallions of Berzelius. I found for this specific heat 

 the number 0*08371, which, multiplied by the atomic weight 

 491, gives the product 41-097. 



The exhibition of M. Batka of Prague contained a large quan- 

 Phil Mag. S. 4. No. 82. Suppl. Vol. 12. 2 L 



