[ i6a ] 



of vegetables requiring various quantities of water and other 

 food ; hence it is that every fort of foil bears vegetables pecu- 

 liarly adapted to it, while others do not grow at all or but ill in 

 it. By the experiments of Mr. Bergman we find that 



Argill takes up 2, 5 times its weight of water when faturated fo 



as to let none drop. 



Magnefia - 1,05 



Chalk - o, 5 



Siliceous fand 0,21; 



Fixed Air. 



That plants do not thrive, but moft frequently perifli, when 

 furrounded by an atmofphere of fixed air, has long been ob- 

 ferved by that great explorer of the moft hidden proceffes of 

 nature, Dodor Prieftley ; but that fixed air imbibed by the roots 

 is favourable to their growth feems well ellablifhed by the expe- 

 riments of Dodor Perceval of Manchefter, and fully confirmed 

 by thofe of Mr. Ruckert. This laft-mentioned philofopher planted 

 two beans in pots of equal dimenfions filled with garden 

 mould. The one was watered almoft daily with diftilled, the 

 other with water impregnated with fixed air in the proportion of 

 ^ cubic inch to an ounce of water ; both were expofed to all 

 the influences of the atmofphere except rain. The bean treated 

 with aerated water appeared over ground nine days fooner than 

 that moiftened with diftilled water, and produced 25 beans, 



whereas 



