12 The Phosirfiates of America. 



they are the best of all soils for the extensive growth of such 

 important plants as wheat, corn, clover, hemp, peas and beans, and 

 of such trees as the chestnut and the oak. 



Limey, or purely calcareous, are even lighter than sandy soils, 

 and when, as is sometimes the case, they are very white and dry 

 they are absolutely barren. 



Such as these are, however, rarely encountered, for we generally 

 find them mixed with a sufficiency of clay to give them some 

 degree of consistency and render them available for ordinary pur- 

 poses. Few soils are entirely devoid of lime, owing to the fact 

 that all rocks contain it in greater or lesser proportion, and because 

 it is transported in immense quantities by waters, in the form of bi- 

 carbonate, and deposited. If it were otherwise, or if, in the absence 

 of lime, other alkaline substances were not forthcoming, the acid 

 principles secreted by all plants could not be saturated, and the 

 inevitable result would be decomposition and death. In its pure 

 form, however, lime is such an extremely strong base that it is in- 

 compatible with life, and hence it never exists in the soil unless it 

 be combined either with carbonic or silicic or sometimes w T ith sul- 

 phuric and nitric acids. 



It will be thus seen that the study of geology, even if only 

 elementary, enables the agriculturist to more accurately gauge the 

 natural resources of his land, and will teach him how to adapt his 

 ideas upon drainage, irrigation and ploughing to the surrounding 

 circumstances of soil and climate. 



It will also prepare his mind for the teachings of chemistry ; 

 that science which has done more than any other to improve the 

 general condition of mankind, and which will enable him to ob- 

 tain the maximum returns from the soil and from plants. 



If production is to be cheap it must be rapid and plenteous, yet, 

 as we all know, the progress of unaided nature is slow and method- 

 ical, and so chemistry, by investigating the laws which govern the 

 development of all living things and by carefully observing the 

 facts acquired by the practical experience of centuries, has found 

 the means by which the farmer may assist and hasten the natural 

 processes. The work is, of course, still far from complete, but we 

 are at least familiar with the elements essential to plant-growth. 

 We know how these elements are distributed, what portion of them 

 is or should be contained in our soils, and what soils are most pro- 

 pitious for different kinds of plants. 



Sixty years ago the science of agriculture was in its infancy. 



