! I O On the Decomposition and Composition 



ducting powers as to heat and electricity, and in their quali- 

 ties of chemical combination. 



Their low specific gravity does not appear a sufficient rea- 

 son for making them a new class ; for amongst the metals 

 themselves there are remarkable differences in this respect, 

 platina being nearly four times as heavy as tellurium *; and 

 in the philosophical division of the classes of bodies, fhe 

 analogy between the greater number of properties must al- 

 ways be the foundation of arrangement. 



On this idea, in naming the bases of potash and soda, it 

 will be proper to adopt the termination which, by common 

 consent, has been applied to other newly discovered metals, 

 and which, though originally Latin, is now naturalized in 

 our language. 



Potasium and sodium are the names by which I have ven- 

 tured to call the two new substances : and whatever changes 

 of theory, with regard to the composition of bodies, may 

 hereafter take place, these terms can scarcely express an 

 error; for they maybe considered as implying simply the 

 metals produced from potash and soda. 1 have consulted 

 with manv of the most eminent scientific persons in this 

 country, upon the methods of derivation, and the one I 

 have adopted has been the one most generally approved. It 

 is perhaps more significant than elegant. But it was not 

 possible to found names upon specific properties not com- 

 mon to both ; and though a name for the basis of soda might 

 have been borrowed from the Greek, yet an analogous one 

 could not have been applied to that of potash, for the an- 

 tients do not seem to have distinguished between the two 

 alkalis. 



The more caution is necessary in avoiding any theoretical 

 expression in the terms, because the new electro-chemical 

 phaenomena that are daily becoming disclosed, seem di- 



* Tellurium is not much more than six times as heavy as the basis of soda. 

 There is great reason to believe that bodies of a similar chemical nature to 

 the bases of potash and soda will be found of intermediate specific gravities 

 between them and the lightest of the common metals. Of this subject I shall 

 treat again in the text in some of the following pages. 



stinctly 



