514 SELENIUM. 



ed horse radish was j>erceived, and on closer examination, a peculiar 

 substance was discovered, to which the name of selenium was given. 

 It has been discovered in the form of sulphuret of selenium, among 

 the volcanic products of the Lipari islands ; at Clausthal, in the 

 Hartz mountains, in combination with lead, cobalt, silver, mercury 

 and copper ; in several varieties of sulphur, in the sulphuric acid of 

 Nordhausen, and in that manufactured from the sulphur of pyrites, 

 from the isle of Anglesea. 



2. NAME. From 2eX>jvif], the moon, in analogy with tellurium, 

 from tellus ; the substance having some resemblance to tellurium, 

 and having at first been mistaken for it by Berzelius.* 



3. PROCESS. The process of Berzelius being very long, the 

 shorter one of Lewenau is here abridged. 



The red deposit 1 Ib. is placed in a 2 quart tubulated retort, 

 whose sides must not be soiled ; it is placed in the sand bath, and 

 connected with a large globular receiver, joined by a Woulfe's tube, 

 to a flask full of water, and all properly luted. 



Nitro muriatic acid, composed of 8 muriatic, sp. gr. 1.2, to 4 of 

 nitric, sp. gr. 1.5,j* was now introduced by portions, to the bottom 

 of the retort, intervals being allowed for the subsidence of the effer- 

 vescence, and of the heat. 



Red vapors escaped, the liquid in the retort became dark gray, 

 and that in the Woulfe's bottle, reddish yellow. 



The fluid being distilled over in the retort, a reddish yellow gas 

 was disengaged, and near the end, small yellow stellated crystals 

 lined the neck of the retort, which disappeared with the increase of 

 the heat ; most of the liquid having thus passed, more acid was ad- 

 ded in portions, and a violent action ensued at every addition, the 

 water in the flask being several times changed, as it became satura- 

 ted with the acid vapors. All the liquors being redistilled from 

 the retort, an insoluble residuum, of a deep red color, supposed to 

 be selenium, now occupied its bottom and sides. To dissolve it, 

 l Ibs. of fuming nitric acid was next added, and distilled nearly to 

 dryness. The residuum was then washed with boiling distilled 

 water, till it came off tasteless, and the filtered fluid was of a light 

 yellow. J This fluid contained the selenium in the form of selenic 

 acid, and to precipitate it, (neglecting the metals that might be in so- 

 lution,) recently prepared sulphite of ammonia, in large excess, was 

 added, which threw down the selenium in the form of large cinnabar 



* See Ann. de Chim. et de Phys. Vol. IX, and Ann. Phil. Vol. VIII, N. S. and 

 Vol. XIII. 



t The author speaks of 12 Ibs. of the mixed acid, but this seem? disproportioned 

 Jo the size of the retort. 



J The distilled fluid was found to be slightly seleniferous. 



