38 AGRICULTURE. 



Carbonate of lime . 46.34 63 



Carbonate of magnesia 6.77 00 



Silica .... ]3.49 00 



Alumina . . . 14.86 16 



Metallic oxydes . . 10.52 00 



SECOND EXPERIMENT. 



Two rhododendrons were taken, one from the 

 calcareous soil of Mont de la Salle, the other from 

 the granitic soil of Mont Severn. Of a hundred 

 parts, the former gave fifty seven of carbonate of 

 lime and five of silica; the latter, thirty or*carbon- 



ate of lime and fourteen of silica. 







THIRD EXPERIMENT. 



This was made to determine whether vegetables, 

 the product of a soil having in it no silica, would, 

 notwithstanding, partake of that earth. Plants were 

 accordingly taken from Reculey de Thoiry (a soil 

 altogether calcareous), and the result was a very 

 small portion of silica. 



These experiments, says Chaptal, leave little, if 

 any doubt, that vegetables derive the earthy matter 

 they contain from the soil in which they grow.* 



II. Of water, as an agent in vegetation. 



Seeds placed in the earth at a temperature above 

 the freezing point, and watered, will develop ; that 

 is, their lobesf will swell, their roots descend into 

 the earth, and their stems rise into the air. But 

 without humidity they will not germinate ; or, if de- 

 prived of humidity after germination, they will per- 

 ish. When germination is complete and the plant 

 formed, its roots and leaves are so organized as to 



* Schaeder maintains the doctrine, that the earths found in 

 plants are created there by the process of vegetation. His essay 

 on this subject was crowned by the academy of Berlin in 1801. 

 His experiments were the first to determine the different quan- 

 tities of silica found in different kinds of grain. 



t Moisten a bean in warm water, and detach the skin that 

 covers it, and it readily divides into two parts ; these are called 

 lobes. 



