ivh'ich lecomes a violet-coloured Gas ly Heat. 5 



a dense precipitate of a pale lemon colour : this precipitate, when 

 collected and examined, proved to be fusible at a low red heat, 

 and then became of a red colour. When acted upon by fused 

 hydrate of potassa, it was rapidly decomposed, and a solid sub- 

 stance, having all the characters of oxide of silver, was formed. 

 The matter soluble in water separated by a filter, and, acted 

 upon by sulphuric acid, afTorded the peculiar substance. 



A solution of potassa, after being boiled on the precipitate, 

 afforded the peculiar substance, when treated by the same acid. 



The precipitate was much more rapidly altered by exposia-e 

 to light, than the muriate of silver, and was evidently quite a 

 distinct body. 



Conceiving, from the action of potassa upon it, that it must 

 be a compound of the peculiar substance and silver, I endea- 

 voured to form it directly by the combination of the two bodies. 

 I introduced some of the substance into the closed end of a small 

 glass curved tube, and placed in the upper part of it some silver 

 foil ; I lieated the foil nearly to redness, and then passed the 

 substance over it in vapour : there was an immediate action, 

 the silver was rapidly dissolved, and a fusible substance formed, 

 in all its obvious sensible and chemical characters, the same as 

 that obtained from solutions of the substance by nitrate of silver. 



The modes which occurred to me, as most likely to effect its 

 decomposition by chemical agents, were the action of the highly 

 inflammaljle metals upon it which unite to oxygen and chlorine, 

 or the action of chlorine which in general tends to the expulsion 

 of oxygen, and to the separation of inflammable bases from that 

 principle. 



I heated some potassium in a little glass tube, and passed 

 some of the substance in vapour over it : at the moment the va- 

 pour came in contact with th.e potassiimi, there was an inflam- 

 mation, and the potassium burnt slowly with a pale blue light. 

 There was no gas disengaged when the experiment was repeated 

 in a mercurial apparatus. > 



The substance formed by the action oT potassium was white, 

 fusible at a red heat, and soluble in water. It had a peculiar 

 acrid taste. When acted upon by sulphuric acid, it effervesced, 

 and the peculiar substance appeared. 



It was evident that in this experiment there hail been no de- 

 composition of the body; the result seemed to depend merely 

 upon the combination of it with the potassium. 



I exposed the body to the action of chlorine in a small glass 

 tube ; it absorl>ed the chlorine, and a substance formed wliich 

 was volatile bv heat, and which appeared as a yellow solid ; it 

 was solul)le in water, and rendered the water of a yellowish- 

 green colour and strongly acid ; the solution when acted upon 

 A3 by 



