52 Mr. Thomson on Sc/ciiitini. '[Jan, 



Article IX. 



On the Discovert/ of Se/enium in the Sulphuric Acid made from 

 the Pi/riies oj Anglesey. By Edmund P. Thomson, Esq. 



(To the Editors of the Annals of Philosophy .) 



OENTLE3IEX, Manchester, Dec. 16, 1824. 



I BEG to send for your particular notice and examination, a 

 substance that has lately come under my observation, and which, 

 from the examination 1 have given it, I have no doubt is selenium, 

 the substance discovered by Berzelius in the sulphur extracted 

 from pyrites at Ftdilun, in Sweden, an account of which will be 

 found in the Annals of Philosophy, vols. xiii. xiv. xv. The pre- 

 sence of this new body, in one of the operations at my manufac- 

 tory, will not be surprising, when it is known that in making 

 muriatic acid I use sulphuric acid which is prepared from pyrites, 

 at the works of my friend Mr. Robert Mutrieof this town. 



The Selenium distils over with the muriatic acid into the 

 receivers, and in the course of two or three days, it falls to 

 the bottom of the vessels in the form of a reddish brown 

 substance, which does not appear to deteriorate the acid in 

 the least. The quantity of this new substance produced from 

 100 parts of the sulphuric acid (made from the pyrites) I have 

 not yet been able to ascertain, but have reason to suppose it to 

 be very small. Through the kindness of Mr. Robert AT utrie, I 

 am enabled to furnish you Avith specimens of the pyrites used at 

 his manufactory. 



The pyrites is obtained from the Paris Mountain in the 

 island of Anglesey, and there are two or three descriptions of 

 them, but all from the same mountain. 



I remain, Gentlemen, yours most respectfully, 



Edmund P. Thomson. 



Experiments on the above described Selenium. By J. G. Chil- 

 dren, FRS. Sec. 



I have submitted the red substance forwarded to us by the 

 kindness of Mr. Thomson, to a few experiments, in order to 

 obtain unequivocal evidence of its containing selenium. 



A fragment, heated on a slip of platina foil by the spirit 

 lamp, tinged the flame of a beautiful azure blue colour. A 

 Tjortion heated by the spirit lamp in a glass tube closed at 

 one end, gave oH* first acidulous water ; some sulphur next sub- 

 limed and condensed at a little distance from tha flame, and 

 soon after a red substance, which condensed on the sides of the 

 tube between the flame and the sulphur, and very near the 

 former. During the subhmation of the red matter, the lower 



