(93) 



steep mountain sides, by the action of washing rains, this matter 

 has been carried off. Again, in many sections, the fertile matters 

 have been exhausted, or so nearly so, that the products of the soil 

 cease to be remunerative. It is the province of scientific agricul- 

 ture to point out these deficiencies and direct the remedy. 



The soil originally consisted simply of the debris of the rocks 

 or clay. It is composed of the elements of the rocks, together 

 with an intimate admixture of some mineral substances. In limit- 

 ed patches the soil partakes of the character of the formations un- 

 derneath. Thus, in iron districts, the soil in places shows the 

 presence, in considerable quantities of iron, making the earth red 

 or brown. In sandstone countries the clay has a quantity of sand 

 overlying it, and among the primitive rocks scales of mica glisten 

 on every side. The weight of a cubic foot of thoroughly dried 

 soil averages as follows : 



Pounds. 



Siliceous sand 111.3 



Calcareous sand 113.6 



Sandy clay 97.8 



Loamy clay 88.8 



Stiff clay 80.3 



Slaty marl 112. 



Fertile mould 68.7 



Common arable soil 84.5 



Chemists, from the earliest times, have been struck with the 

 great proportion of insoluble to soluble substances in the soil. 

 These insoluble substances will resist the action of acid and alkali 

 in any quantities short of destroying vegetation. Analysis have 

 striven by the aid of weak solutions of acids and alkalies to effect 

 this, and though the science is by no means perfect, they have suc- 

 ceeded in rendering much inert matter, that has hitherto cumbered 

 the land into plant food. In an average of many kinds of soil the 

 proportions are, of 



Insoluble matters '. 89.305 



Soluble matters 2.047 



Phosphate, carbon, and sulphate lime 3.160 



Thus it is seen that of the great mass of soil, ranging from a 

 few inches to many hundred feet thick, only a very small per cent 

 is available to vegetation. Further, chemical analysis has also de- 

 veloped the fact that all animal tissues are composed of these 



