( 38 ) 
of plants, then would be all:soils alike productive; 
or in other words, if air and water exclusively supply 
this food, then would a soil of pure sand be as pro- 
ductive as one of the richest alluvion. 
_ 2. Though plants may be made to grow in pound- 
ed glass, or in metallic oxides, yet is the growth, in 
these, neither healthy nor vigorous : and, 
3. All plants, on analysis, yield an earthy pro- 
duct;(1) and this product: is found to partake of 
the earth that predominates in the soil producing 
the analyzed plant. This important fact is proved 
by De Saussure. 
FIRST EXPERIMENT. 
Two plants (the pinus abies) were selected, the 
one froma calcarious, the other from a granitic soil, 
the ashes of which gave the following products : 
Granitic soil. Calcarious soil. 
Potash 3 60 15 
Alk, and mu. sulphates.4 24 | 15 
Carbonate of lime 46 34 63 
Carbonate of magnesia 6 77 00 
Silica lide 13 49 00 
Alumina 14 86 (16 
Metallic oxides 10 52 00 
- 
SECOND EXPERIMENT. 
Two Rhodedendrons were taken, one from the 
calcarious soil of Mount de la Salle, the other from 
the granitic soil of Mount Bevern. Of a hundred 
parts, the former gave fifty-seven of carbonate of 
NY 
(1) Davy says this never exceeds one fiftieth of the whole product. 
