18 DEPARTMENT OF AGRICULTURE GEORGIA. [304] 



wood burns, or it may be gradual, as is seen in the slow 

 decay of vegetable matter, the rusting of iron, etc. Vege- 

 tation, which contains much nitrogen, as pea or bean-vines 

 or clover, decomposes or decays, by oxydation, much more 

 rapidly than substances in which starch, cellulose, or other 

 carbonaceous compounds, more largely predominate. 



Oxygen is the great supporter of combustion in its widest 

 sense. 



The most combustible material will not burn without 

 access to oxygen. Excluded from moisture and oxygen, 

 vegetable matter will not decay, animal matter will not 

 putrify. Water, thrown upon a flame, spreads over the 

 burning substance, excludes the air with its contained oxy- 

 gen, and the flame is extinguished. Fruits, vegetables and 

 meats, heated to drive off the air, and to destroy the germs 

 of fungoid ferments, and then hermetically sealed, escape 

 decomposition and fermentation. 



Oxygen has a tendency to unite with nearly every other 

 substance, and, if the union is effected rapidly, light is 

 generally, and heat always, produced. If the union takes 

 place slowly, these phenomena are not perceptible, and the 

 former does not generally occur. 



Fermentation is a peculiar kind of decay or decomposition, 

 which apparently acts spontaneously on animal or vegeta- 

 ble matter, "involving heat and a rapid evolution of gas." 

 " There are several kinds of fermentation : vinous, acetous, 

 lactic, etc. All three of these processes may take place at 

 once in a mixture' of cellulose, abuminoids, and sugar," 

 (Pendleton's Scientific Agriculture). The primary cause 

 of fermentation is the presence of microscopic fungi, which 

 act as a ferment. The germs of these float in the air and 

 germinate, when brought into contact with substances 

 suited to their growth. They even exist in the pores of 

 substances, in which they germinate, under favorable cir- 

 cumstances of warmth and moisture, and thus give rise to 

 fementation, even in closed vessels. 



