CHEMISTRY AND FARMING. 297 



exfoliation may be obtained, by supposing an individual to 

 have been placed upon our planet at a timcwlicn it was a hard, 

 impenetrable mass of rock. Suppose him to have lived through 

 all the great epochs of time until the present, and to have wit- 

 nessed the gradual metamorphosis from barren sterility to the 

 extreme of vegetable luxuriance. Suppose him capable of wit- 

 nessing the gradual crumbling of the adamantine masses, and 

 the formation of cultivatable soils. If the agoiicics in past 

 ages were the same as are now at work, he would have seen 

 that every flash of lightning that shot athwart the sky, by de- 

 composing the atmosphere, produced a trace of nitric acid, and 

 that tliis, falling upon the rock, aided in tlie work of separation. 

 He would have seen that the carbonic acid of the air, the rapid 

 freezing and thawing, the mechanical eliects of rain, the attri- 

 tion of dust moved by winds, all conspired to reduce the seem- 

 ingly defiant quartz, and talc, and gneiss, to a finely subdivided 

 powder capable of sustaining vegetable life. The chemistry of 

 these atoms of dust is very easily understood. God, in the be- 

 ginning, made use of about sixty different kinds of materials in 

 constructing our planet, and he selected ten or twelve only of 

 them, from which to form all kinds of rocks. It follows that 

 the dust atoms must be made up of the same material as the 

 parent rock. From them the mineral food of plants is obtained. 

 The inorganic, or mineral food, which plants require, are prin- 

 cipally silica, lime, magnesia, sulphur, pota.'h and foda. Their 

 presence in the soil is indispensable, as without them no plant 

 growth could begin and continue. A plant has as capricious 

 an appetite for its mineral food as a human being has for its 

 food, and each variety calls for its appropriate nutriment, and 

 if nature docs not supply it sufficiently in tlic soil, or if you, 

 gentlemen, do not step in and furnish it, it famislies and dies. 

 There is as much propriety in saying, when we observe a stock 

 of corn strnggling for existence in an impoveritrhed soil, that it 

 is starving to death, as there is in saying that an animal fam- 

 ishes, when food is withheld. Let us observe still further the 

 striking analogy between plant life and animal life. I have 

 said that both have their appropriate, chosen food. If we place 

 before a favorite horse or ox such forms of food as man re- 

 quires, and withhold hay and grain, their appropriate food, 

 they will ultimately perish. Thus it is with vegetables. If you 



