FOREST CHEMISTRY. 



BASIC ELEMENTS. 



It is a well known fact that the air is composed mainly of three basic 

 elements oxygen, carbon and nitrogen. Oxygen is the support of com- 

 bustion and respiration. For this reason vast quantities are needed, and 

 providentially it is the most abundant element of the earth, and the most 

 widely distributed. It forms from forty-four to forty-eight per cent of 

 the solid crust of the earth, eight-ninths of water and about one-afth of the 

 air. 



MECHANICAL OPERATIONS. 



The basis of the soil is mineral, rock. The coarse pebbles or gravel, com- 

 posed for the most part of quartz, lime and feldspar, were once solid rock, 

 and so the sands and clays. What has crumbled the crystalline rock into 

 such shapes? One of the agencies is water, that sinks into the crevices 

 and porous constituency of the rock, and by its expansion in freezing and 

 reactionary contraction, pry the huge pieces apart and break them asunder. 

 All this while carbonic acid gas and oxygen in water are "Time's busy fin- 

 gers" wearing away the hardest granites. The roots of the great trees 

 penetrate into the cracks, following wherever the dust has crept in, and by 

 their growth dislocate their imprisoned walls. The glaciers carry great 

 stones in masses of ice, grinding slow, but grinding fine, down over the 

 mountain slopes and over the valleys of the mountainous countries, form- 

 ing vast strata of clay, digging out monstrous hollows in the softer rock 

 along the crystalline sides and bottoms for subsequent lakelets to stay in. 



Gerkie, in his Text Book of Geology, page 339, thus outlines the mixed 

 soil-making process: "On the level surface, the weathered crust may re- 

 main with comparatively little rearrangement until plants take root in it, 

 and by their decay supply organic matter to the decomposed layer which 

 eventually becomes what we term 'vegetable soil.' Animals also furnish a 

 smaller proportion of organic ingredients. Though the character of the 

 soil depends primarily upon the nature of the rock out of which it has been 

 formed, its fertility arises in no small measure from the commingling of 

 decayed animal and vegetable matter with decomposed rock." 



CAE30N DIOXIDE. 



In combination with bases, carbon occurs in enormous quantities, par- 

 ticularly in ordinary limestone, chalk, marble, calc-spar, etc. By the 

 "chemistry of nature" it is crumbled, oxydized, enters a gaseous state, and 



