FIXED ALKALIES AND ALKALINE EARTHS. 



earths, on the contrary, which constitute the 

 oxides of these metallic bases, are in constant 

 use, and constitute some of the most important 

 substances known to the chemist. They are the 

 bases of the most common and useful salts, and 

 an accurate knowledge of their atomic weights 

 is of the utmost consequence to the progress of 

 the science. The principal part of our attention 

 will, therefore, be bestowed on the investigation 

 of the atomic weights of these alkaline com- 

 pounds. The knowledge of the atomic weights 

 of the bases will follow as a kind of corollary 

 from that of their compounds. 



SECT. I. 



OF THE ATOMIC WEIGHT OF POTASH AND 

 POTASSIUM. 



THERE are two salts of potash, which, when 

 properly prepared, are destitute of water, and 

 consist respectively of water united to nitric 

 acid and sulphuric acid. These are nitrate of 

 potash, and sulphate of potash. 



Analysis of 1. Nitrate of potash crystallizes in six-sided 

 potash. prisms, terminated by six-sided pyramids. When 

 kept red hot, the nitric acid is gradually dissipa- 

 ted, and pure potash remains behind. It may 

 appear at first sight easy, by this means, to deter- 



