126 SCIENCE OF AGRICULTURE. 



salts and silicates the action of the base is ever the same 

 in vegetation. The base of the silicates and salts acts 

 always in one uniform mode. Peculiarities of action 

 depend on the acid constituent of the salt. Lime, 

 for instance, acts ever the same, whether it is used 

 as carbonate, sulphate, or phosphate, marl, plaster, 

 or bone-dust. The salt is decomposed by the living 

 plant. The various acids combine with the alkalies, 

 as they are eliminated, from the decomposition of 

 the silicates, and the lime, liberated, acts ever as 

 lime. It acts in its caustic state, as a converter of 

 insoluble into soluble geine. If this does not exist 

 in the soil, all the lime in the world would not cause 

 plants to grow. The base of the lime-salts acts 

 primarily on geine, either solving the soluble or 

 converting the insoluble. The same is true of alu- 

 mina, iron and the bases of all salts. The same 

 general rule applies to all alkaline, earthy or metal- 

 lic salts and to silicates. 



" The order in which the farmer may apply salts 

 is the following : Carbonate, phosphate, and sulphate 

 of lime, carbonates, nitrates, muriates, and sulphates 

 of alkalies. No salts, excepting carbonates, can be 

 used in large quantities. The reason is at once ex- 

 plained by the principle of unity of action of the 

 bases. The acid of the salts, eliminated, decompo- 

 ses the geates, rendering the soluble insoluble, the 

 acid combines with any free base, produced from the 

 decomposition of the silicates, and thus prevents that 

 forming soluble geine. Having saturated the bases, 

 any excess acts then as free acid, poisoning the 

 vegetable, as oil of vitriol, or muriatic acid would ani- 

 mals. In carbonates, the acid forms part of the food 

 of plants. The alkaline geates are so very soluble, 

 that when alkalies, as ashes for instance, are freely 

 used, w^e lose a part, by its draining away, or in wet 

 soils becoming too dilute. But a small dose produ- 

 ces all the beneficial effects of a large dose of lime. 

 We have in ashes, not only the alkali to solve geates, 

 but a very large portion of carbonate and phosphate 



