DECOMPOSITION. FERMENTATION. 117 



hydrogen in the egg, warmed a little, attract each other 

 and form sulphuretted hydrogen, which is ready to fly 

 off, and oxygen unites with the other ingredients, forming 

 new compounds. 



385. Fermentation. The oxygen of the air is always 

 ready to unite with other elements. If the juices of 

 plants containing sugar, such as cider, or wine, for 

 example, be carefully kept from the air, they remain 

 sweet. But if the air be admitted, the oxygen immedi 

 ately unites with the albumen of the juice, and then with 

 the sugar, and the Vinous Fermentation begins. If this is 

 allowed to continue, the sugar will be changed into 

 carbonic acid and alcohol. 



Weak wine, cider or beer, exposed to air, at the tem 

 perature of from 70 to 90, gradually grows warmer, 

 and becomes thick by slender threads moving in every 

 direction through it, with a low hissing noise. When the 

 noise has ceased, and the threads have attached them 

 selves to the sides and bottom of the vessel, the liquor, 

 now become clear, has passed through the Acetous Fer 

 mentation, and become acetic acid or vinegar. 



386. The final products of complete decay are univer 

 sally the same. The carbon of organic bodies combines 

 with oxygen and forms carbonic acid. The hydrogen 

 unites with oxygen and forms water, or with nitrogen 

 and forms ammonia ; or with sulphur and phosphorus, 

 forming sulphuretted and phosphuretted hydrogen. The 

 incombustible matters alone remain. Moisture and 

 warmth are necessary at the beginning and at every stage 

 of decomposition. To prevent it, therefore, we have only 

 to keep the substance cold and dry. 



387. It is desirable to keep the stable and cow-house 

 always clean and sweet ; and this may be effectually done 

 by sprinkling a little plaster upon the floor once a day. 



