DK. GOODMAN ON LIGHT, HEAT, ETC. 81 



Stance, it will be remembered, was discovered by Sir H, 

 Davy in October, 1807. Dr. Ure gives the following 

 description of its properties : — 



a. It is lighter than water, being sp. gr. 0*865. 

 h. At common temperatures it is solid, soft, and easily 

 moulded by the fingers. 



c. At 150 Fahrenheit it fuses; d. and in a heat a little 

 below redness it rises into vapour. 



e. When newly cut its colour is splendent white, like 

 that of silver; /. but it rapidly tarnishes in the air; g. to 

 preserve it unchanged, we must enclose it in a small phial 

 with pure naphtha. 



A. It conducts electricity like the common metals, 

 i. When thrown upon water it acts with great violence, 

 and swims upon the surface, burning with a beautiful light 

 of a red colour mixed with violet. 



It. When heated moderately in common air it inflames, 

 burns with a red light, and throws off alkaline fumes ; 

 I. placed in chlorine, it spontaneously burns with great 

 brilliancy, 



m. The attraction of chlorine for potassium is much 

 stronger even than the attraction of oxygen for this metal. 



n. Lastly, of all known substances potassium is that which 

 has the strongest attraction for oxygen, and it produces 

 such a condensation of it, that the oxides of potassium are 

 denser than the metal itself. 



Dr. Faraday has also shown, that after the addition of 

 oxygen and iodine to this substance, the resulting salt is of 

 less volume, and occupies less space, than the original bulk 

 of the potassium itself. 



The vivid and intense light and heat given off by the 

 union of potassium with chlorine, oxygen, sulphur, and 

 phosphorus, seemed to me to exhibit, that this metal possesses 

 a large amount of absolute heat. The intense ajffinity of 

 this substance for e\QciTo-negative bodies appeared also to be 



