CHEMICAL MANUIIKS. 17 



Under this continued though unseen conflict there is an order of 

 phenomena still more profound and mysterious, which I would like 

 to show you, because to my eyes there is nothing more fit to unveil 

 to you the true character of agricultural products, and to show you 

 how this grand act of vegetable life, to which are most intimately 

 joined the most essential conditions of our existence, differs from all 

 other products of human activity. 



GENERAL RULE. 



All work of production presupposes two equally indispensable 

 things a first cause and a source of force. 



Without these two conditions nothing can be produced. 



Whatever we do, the material in use experiences a diminution 

 which we strive to prevent, but cannot entirely avoid. The same in 

 regard to the force expended. We make use of but a part of it the 

 rest is unavoidably lost. I repeat, then, the product, which is the 

 material representative of the work, is unequal to the first cause and 

 the force employed. Take, for example, any industrial labor you will 

 metallurgy, weaving, the mechanical arts. The work is always ac- 

 companied by a double loss of the first material and vital force, 

 produced by friction of intermediate organs and imperfection of 

 apparatus. 



In agriculture the character of the production is different. The 

 earth, through her harvests, returns ten times the value of what we 

 give her by our fertilizers, and every harvest supposes an expendi- 

 ture of force at least five hundred times greater than the sum of the 

 efforts which produced it. 



How can we explain these two opposing facts ? The economy of 

 the assimilation of carbon will teach us. 



All vegetables, as we have said, contain from 40 to 45 per cent, of 

 their weight in carbon. Now, if the carbon comes from the air and 

 is added to the agents which we give the earth to fertilize it, we imme- 

 diately perceive why the earth gives more than she has received. It 

 is the same with regard to oxygen and hydrogen, which represent 

 more than 50 per cent, the weight of vegetable matter, and which are 

 given out by water. 



From this, then, it follows that 95 per cent, of vegetable matter is 

 provided by sources different from the soil, and that the amount fur- 

 nished the soil by human industry is but a fraction of the harvest 

 we draw from it. But this fraction is indispensable, for without it 

 the carbon of the atmosphere, the oxygen and hydrogen of water, 

 would remain in their primitive " state in the domain of inorganic 

 matter, and could not have entered the current of vegetable life. 

 Here is explained the first characteristic of vegetable life. You know 

 now why the earth gives more than it receives. The excess comes 

 from the air and the rain. 



The following table is an undeniable demonstration of the fact. It 

 is understood that what I say of wheat is equally applicable to other 

 plants : 



