182! .] during the Distillation of Nitric Acid, 217 



Held in the flame of a lamp, it burned with a greenish-blue 

 flame, giving a slicjht smell of oxymuriatic gas; and when 

 heated in a glass tube, it melted, boiled, and sublimed in 

 needles, at a heat between 350° or 400°, and it sublimed slowly 

 in long needles without melting at a heat of about 250°. 



Potassium burned with a vivid flame in its vapour in an open 

 tube ; a great quantity of carbon was deposited, and water 

 poured upon it gave, after saturation with nitric acid, a copious 

 precipitate with nitrate of silver. 



The small quantity which I have as yet obtained of this sub- 

 stance, and want of leisure, have prevented me from making 

 more experiments upon it ; but I purpose doing it as soon as the 

 one and the other are more at my disposal : till then, I suspend 

 forming any opinion of its composition. In some respects, it 

 seems to resemble the perchloride of carbon which Mr. Faraday- 

 has lately succeeded m producing, and has so ingeniously 

 examined. 



It IS rather strange that sulphur should sublime unaltered in 

 the vapour of nitric acid, as 1 have mentioned to occur in the 

 case of this distillation of nitric acid, but it is really the fact, 

 and may be accounted for by want of water for the sulphuric 

 acid to combine with.^ 



Experiments on the a/jove described Substance. Ry R. Phillips, 

 Ji FRSE. 8cc. and M. Faraday, Chemical Assistant at the Royal 

 45i Institution. 



In order to purify this substance, a small quantity of it was 

 passed in a state of vapour over hot lime. By this operation, a 

 little sulphur, muriatic acid, and other impurities, were separated. 

 The pure substance obtained was dried over sulphuric acid in the 

 receiver of the air-pump, and it had then a white crystaUine 

 appearance; by subjecting it to heat, it was volatilized, and 

 then condensed, in beautiful acicular crystals. 



In the substance thus purified, there remained no traces eitheir 

 of chlorine or sulphur, as described by M. Julin, and it exhibited 

 the following properties : It burned with a strong bright flame ; 

 at a heat below redness, it sublimed without undergoing any 

 change ; when passed through a red-hot green glass tube, there 

 was a slight appearance of decomposition, a small quantity of 

 charcoal being deposited, and the substance became brown, but 



♦ On his departure for the Continent, M. Julin left the above account, and also 

 some of the substance which he has described, in the hands of the Editor, with permis- 

 sion to make use of both as he wished From the circumstance mentioned by M. Julin 

 of its appearing to resemble the perchloride of carbon, the substance in question was' 

 shown to M. Faraday, and with his assistance the additional experiments now describeli • 

 wexe made. h 



