CHYMISTRY APPLIED TO AGRICULTURE. U 



1. Electricity is developed by friction, and transmitted 

 by simple contact. It is accumulated in bodies when they 

 are insulated ; and it is communicated in the same man- 

 ner as heat, when bodies which are non-electric ap- 

 proach those which are electric. 



The singular properties of the electric fluid contained 

 in the atmosphere, and the frequent variations which it 

 undergoes, give rise to numerous phenomena, for which 

 observation and experiment enable us to account. When 

 this fluid is abundantly diffused throughout the atmo- 

 sphere, it exercises a powerful influence over vegetation, 

 excites the action of oxygen, and determines the conden- 

 sation of the aqueous fluid. Davy has observed that grain 

 germinates more quickly in water charged with positive 

 electricity, than in that which contains the opposite prin- 

 ciple ; and that it is a well known fact, that fermentation 

 takes place most rapidly during a thunder-storm, and 

 that a liquid, composed of a variety of principles not very 

 closely united, milk for instance, is decomposed, and be- 

 comes acid under a highly electric state of the air. 



2. Whatever may be the opinion we may adopt, as to 

 the nature of the principle of heat, there can be no doubt 

 that there exists in the atmosphere, and in all terrestrial 

 bodies, an imponderable fluid, unequally imparted to them, 

 and which renders their state solid, liquid, or gaseous, 

 according as the affinity, existing between their par- 

 ticles and the fluid of heat, is more or less strong. It is 

 this state which we regard as the natural state of bodies. 



Exposed to an equal degree of atmospheric tempera- 

 ture, all bodies, in their natural state, are penetrated by 

 unequal quantities of the fluid of heat ; but as the fluid is 

 in combination with the particles of the bodies, and thus 

 forms one of their constituent principles, it does not de- 

 velope its most important property, which is that of heat ; 

 and in this state it has been agreed to call it caloric, and 

 it only takes the name of heat when it is free, and disen- 

 gaged from all combination. 



Caloric, interposed between the molecules of bodies, 

 tends to separate them from each other ; and when accu- 

 mulated beyond its natural quantity, the excess acts as 

 heat ; changing the form of bodies, and causing them to 

 pass from the solid to the liquid state, or from the last to 

 that of vapor. 



Those bodies which exist naturally in a gaseous state, 



