8 Professor T. E. Thorpe [Jan. 17, 



lower, or negative surface, there was no liberation of elastic fluid ; but 

 small globules, having a high metallic lustre, and being precisely 

 similar in visible characters to quicksilver, appeared, some of which 

 burnt with explosion and bright flame, as soon as they were formed, 

 and others remained, and were merely tarnished, and finally covered 

 by a white film which formed on their surfaces." 



He goes on to say : — 



" Soda, when acted upon in the same manner as potash, exhibited 

 an analogous result ; but the decomposition demanded greater inten- 

 sity of action in the batteries, or the alkali was required to be in 

 much thinner and smaller pieces. 



" The substance produced from potash remained fluid at the 

 temperature of the atmosphere at the time of its production : that 

 from soda, which was fluid in the degree of heat of the alkali during 

 its formation, became soHd on cooling, and appeared having the lustre 

 of silver." 



It would seem from this description of its properties that the 

 potassium Davy first obtained was alloyed with sodium owing to the 

 fact that the potash contained soda. Potassium is solid up to 143° F., 

 whereas, as Davy was the first to show, an alloy of potassium and 

 sodium is fluid at ordinary temperatures. 



On account of their alterability in contact with air, Davy had 

 considerable difficulty in preserving and confining the new substances 

 so as to examine their properties. As lie says, like the Alkahests 

 imagined by the Alchemists, they acted more or less upon almost 

 every body to which they were exposed. Eventually, he found they 

 might be preserved in mineral naphtha. 



The " basis " of potash was described by him as a soft malleable 

 soUd with the lustre of polished silver. 



" At about the freezing point of water it becomes harder and 

 brittle, and when broken in fragments, exhibits a crystallised texture 

 which in the microscope seems composed of beautiful facets of a 

 perfect whiteness and high metallic splendour. It may be converted 

 into vapour below a red heat, and may be distilled unchanged, and is 

 a perfect conductor of heat and electricity. Its most marked differ- 

 ence from the common run of metals is its extraordinary low specific 

 gravity." At the time of its discovery, it was the hghtest solid 

 known. 



The " basis " of soda was found to have somcAvhat similar 

 properties. It was slightly heavier than the " basis " of potash, and 

 fused at a higher temperature. 



Davy next examined the behaviour of the new substances towards 

 a large number of reagents, but as his observations are now the 

 common property of the text-books, it is unnecessary here to dwell 

 upon them. 



He then enters upon some general observations on the relations 

 of the " bases " of potash and soda to other bodies : 



