81 On Selenium from Lukawitz in Bohemia. 



prepared, immediately previous to its application, by passing 

 sulphurous acid gas through a solution of carbonate of am- 

 monia. The precipitate thus produced was collected on ti 

 filter, and first edulcorated with cold and afterwards with hot 

 water. On boiling the fluid which had passed the filter, and 

 which had a strong smell of sulphurous acid, nothing more 

 was separated from it, either alone or with further addition. 

 The bulky red precipitate became diminished in a consider- 

 able degree on pouring the hot water upon it, and changed in 

 colour to lead-gray, and then most resembled the gray pow- 

 der which is obtained by exposing the triple-salt of platinum 

 to a red heat. The powder was now distilled in a small glass re- 

 tort; but it required a considerably greater heat than is neces- 

 sary for the distillation of sulphur ; viz. a dark red heat, until 

 the retort began to soften. In this process I observed the 

 same changes of colour and lustre, according to the various 

 circumstances of cooling and the different modifications of the 

 state of the aggregate mass, as those which have been de- 

 scribed bj- Berzelius. To detail the experiments I subse- 

 quently undertook with this new and interesting substance, 

 would, as I obtained no new results, merely serve to confirm 

 the statements of that chemist ; which would be the moi'e su- 

 perfluous, as his well-known exactness and veracity allow no 

 room for doubt. I cannot however agree with Berzelius in 

 arranging selenium with the metals, now that I am acquainted 

 with it from my own observation ; but I have given it, in my 

 lectures, a place among the simple inflammable bodies, as they 

 are called, immediately succeeding sulphur. 



The sulphur burnt in the chambers of the manufactory at 

 Lukawitz is obtained from pyrites found in the vicinity of 

 that place, and the enormous abundance of which occasioned 

 the establishment of these works. A quantity of the pyrites 

 was sent me as a sample; but they did not differ in their ex- 

 ternal appearance from ordinary pyrites, nor could our mine- 

 ralogists here observe any distinguishing characters in them. 

 I assayed them for selenium, but could not discover any; so 

 that it must either occur in them in such small proportion as 

 to escape detection by the usual tests, or in single specimens 

 only, and those which I examined must have accidentally been 

 free from it. 



In the course of last winter I had opportunity of confirm- 

 ing, by direct experiments, the supposition of Berzelius, that 

 the smell of tellurium in vapour might be owing to selenium. 

 M. II. von Gersdorf, the principal assayer here, and of equal 

 ability as a chemist and mineralogist, gave me, for further exami- 

 nation, a portion of sulphur which he had obtained by distil- 

 lation 



