PHYSICAL AND LlTfiRARY. 22^ 



At the foot of the fir ft column feveral 

 of the metals might follow, and after thefe 

 the earth of alum j but as I don't know 

 what number of the metals (hould precede 

 that earth, I have left it to be determined by 

 further experience. 



The volatile alkali and magnefia are 

 placed in the fame Hne of this column ; be- 

 caufe their force of attradion feems pretty 

 equal. When we commit a mixture of 

 magnefia and fait ammoniac to diftillation, 

 the alkali arifes and leaves the acid with the 

 magnefia ; becaufe this earth, by attrafting 

 the acid, repreifes its volatility, and it feems 

 alfo to diminiih the cohefion of the acid and 

 alkali, and to render them feparable by a 

 gentle heat. If the magnefia be faturatcd 

 with air, this likewife, on account of its 

 volatile nature and attraftion for the alkali, 

 is driven up along with it, and makes it ap- 

 pear under a mild form, and in the fame 

 manner do the alkali and air arife from a 

 mixture of fait ammoniac and of a crude 

 calcarious earth. 



F f Art. 



