FOREST CHEMISTRY. 71 



from the atmosphere, and, therefore, that the atmosphere contains less 

 carbonic acid than it did at the beginning of the carboniferous period, by 

 the amount stowed away in the coal of the globe." 



This storage of energy is going on to-day, although not in the same de- 

 gree. "As long as life continues," says Kemsen, "plants and animals are 

 storehouses of energy." The chemical process of setting free the heat 

 evolves a power of work. Thus the burning of the coal drives the engine, 

 cooks our food and warms our rooms. Oxidation or decomposition of car- 

 bon dioxide is an evolution of latent heat not always perceptible or appre- 

 ciable, but sufficient in its silent operations to run the machinery of plant 

 and animal life. Think of the vast storage of these elements in our grow- 

 ing woods, providentially reserved for our use. 



WOODLAND LATENT WARMTH. 



All plant life is dependent on the decomposition of carbon dioxide and 

 water, taking place constantly on the face of the earth. In the storage 

 process or in its decomposition, heat, originally wrought by the action of 

 the sun, is the result, which work is, no doubt, an unseen factor in plant 

 growth. Humboldt claims "that trees are conductors of heat, and convey 

 the warmth of the atmosphere to the earth when the earth is colder than 

 the air and most needs it." And so the reverse. Trees being the storage 

 of heat, they radiate it in winter. The foliage in summer being a shield 

 against the hot sun, and the evaporation underneath being an expanding 

 process, there is a reaction to cool down. The forest, then, is an equalizer 

 of temperature in winter and summer. 



WATER. 



Water acts as a solvent, and is essential in the chemical processes herein 

 mentioned. It is composed of one volume of oxygen to two of hydrogen. 

 The ratio by weight of equal volumes of hydrogen and oxygen is 1:15.96. 

 Water is a very stable compound. Without it there could be no life sus- 

 tained upon the earth. Hydrogen is contained in combination with carbon 

 and oxygen or with carbon, oxygen and nitrogen, and occurs "in most 

 substances of animal and vegetable origin, such as the various kinds of 

 wood and fruits and the tissues of all animals." 



NITROGENOUS ELEMENT. 



Nitrogen is the main constituency of the air. It does not support com- 

 bustion nor respiration. It is not a poison, but animals would die in it for 

 want of oxygen. Give twenty-one volumes of oxygen and seventy-nine 

 volumes of nitrogen, or by weight twenty-three per cent of oxygen and 

 seventy-seven per cent of nitrogen, and human beings and animals will 

 live in the mixed compound. 



Nitrogen, it is said, "dilutes the oxygen." This is an inadequate con- 

 ception of its use. It is an essential constituent of plants and animals. 

 "The animals get their nitrogenous compounds from the plants, and the 

 plants get theirs partly at least from the soil." When the plants and 

 animals decompose in the soil, by a process known as death, "the nitrogen 



