322 Professor Davys Notice of Carburet of Potassium, 



filled with mercury, on letting up a few drops of water, 

 gas was copiously disengaged, and as the mercury descended 

 along the tube, small portions of the substance became 

 ignited, exhibiting the appearance of bright sparks of fire 

 in continued succession. 



In another experiment with the iron bottle, the author 

 procured no potassium, but a small quantity of a substance 

 partly in powder, and partly in small lumps, of a dense 

 black colour. This substance the author regards as car- 

 buret of potassium. It exhibits no appearance of crystal- 

 lization to the naked eye ; but when viewed with a glass of 

 high magnifing power, the author thinks he has observed 

 congeries of exceedingly minute four-sided prisms, trun- 

 cated at their solid angles. When the carburet is exposed 

 to the air, it soon undergoes changes, oxygen and water 

 appear to be absorbed, and caustic potash and carbon 

 remain. 



When the carburet is put into water, both substances are 

 decomposed, one portion of the carbon unites with the 

 hydrogen of the water to form the new bi-carburet of 

 hydrogen, which is the only gaseous product, the remainder 

 being disengaged, whilst the oxygen of the water and the 

 potassium form potash. 



Alcohol and turpentine act feebly on the carburet, acids 

 strongly. 



The carburet undergoes partial decomposition at a dull 

 red heat in close vessels, potassium slowly rises from it, 

 whilst the carbon remains of a deep and bright black colour. 



The author regards the pure carburet as a binary com- 

 pound of one proportion of carbon and one of potassium. 



New Bi-carhuret of Hydrogen, 



This gas was obtained by the action of carburet of potas- 

 sium on water. It is highly inflammable, and when kindled 

 in contact with air, burns with a bright flame, apparently 

 denser and of greater splendour than even olefiant gas. 

 If the supply of air is limited, the combustion of the gas is 

 accompanied with a copious deposition of carbon. When 

 the new gas is brought in contact with chlorine gas instant 

 explosion takes place, accompanied by a large red flame, 

 and the deposition of much carbon, and these effects readily 



