350 Tjjaxsactioxs of the Amebic ax Ixstitutb. 



and stable floors to be the same substance that is most needed in 

 sprouting stem and springing leaf, we add plaster of paris or dry 

 muck to the mass, and fix the vapor to feed our crops, instead of 

 allowing it to waste in the air. More than all, chemistry takes inert 

 materials, made up of elements so firmly combined that the subtle 

 strength of vegetable demand and the agencies of air and moisture 

 can separate them but slowly, and in a few hours it converts the 

 whole into manures so soluble that they may be at once assimilated 

 by the rootlets and transmuted to cell and tissue and fibre. By these 

 means the flint-like nodules termed coprolites, the refuse of fishes 

 and marine animals that were fossils before man came upon the 

 earth, and the stony deposits of N"avassa, hardened under the rains 

 of a hundred ages, are fitted for transformation in a single season 

 into the structure of fruit and grain. 



But why multiply examples to show the importance of chemistry 

 in its application to agriculture ? Is it not enough that, aside from 

 the introduction of new implements and machinery, the great and 

 acknowledged improvements made during the past half century in 

 the art of husbandry, have rested upon chemistry as upon a founda- 

 tion of stone. Witness the manufacture of portable fertilizers, the 

 rotation of crops, the practice of green manuring, and even the feed- 

 ing of cattle ; for have not chemists told us the relative values of dif- 

 ferent kinds of food, for example, that five pounds of oil cake 

 contain more nutriment than a hundred weight of turnips ; and have 

 not farmers, acting on theories like these, found them, by the stern 

 tests of experience, to be correct. In the old times farming had only 

 the chances of successful guess-work ; now it has the certainties of 

 applied science, and there is just as much difierence between the two 

 as between the old " scribe rule" of " cut and try," in building, and 

 the geometrical plans of the skilled architect. A century and a quar- 

 ter ago Jethro Tull taught that the roots of plants took up little par- 

 ticles of dirt and transmuted them into vegetable structures. IIow, 

 with such teachings, could we be led to appreciate the importance of 

 ammonia in solution in the soil. It is but little more than thirty 

 years since it was a mooted question as to whether the elements of 

 the ash of a plant were essential in the soil in which it was grown. 

 ITow, until this point Avas settled, could the agriculturist see the 

 importance of supplying potash or phosphoric acid or lime to supply 

 material for the growing organism. But a knowledge of such truths 

 once gained, the farmer proceeds to act undcrstandingly upon the 



