wlien supplied witli air. In canning fruits the housewife heats the 

 fruit to boiling point for the purpose of destroying germs which 

 cause fermentation and decay. She then seals the fruit in air tiij;ht 

 cans. In siloing tlie farmer constructs an air tight compartment 

 which he fills with chopped green fodder. As soon as this is filled 

 active chemical changes take place which result in generating heat. 

 In the process of fermentation oxygen is consumed and most of tlie 

 air within the mass is expelled because heating it has increased its 

 volume. When the air has been expelled or consumed, fermenta- 

 tion ceases and if the outside air is then excluded no further change 

 will take place in the quality of the silage. If the plants used in 

 filling the silo are very succulent the excess of water will check the 

 first chemical changes which produce heat necessary to destroy germs 

 of ferment. In this way sour silage is made. It is much less whole- 

 some than sweet silage. It should be stated that there is no formula 

 which will guarantee a specihc degree of sweetness and that the 

 terms sweet and sour silage are used in a relative sense. The 

 sweetness of the food depends on ihe stage to which tlie first fermen- 

 tation was carried and tlie subsequent exclusion of air. The best 

 silage, therefore, can only be made from fairly well ripened plants 

 packed in a practically air tight compartment. 



Silos may he huilt wUJiln a harn^ or as an addition to a ham', 

 air may he excluded more completely from cylinder shaped silos 

 than from those having corners. — In all silos the greatest waste 

 occurs around the sides, particularly in the corners, because the air 

 has access to these parts. The fodder is not packed tightly in the 

 corners ; the air fills the interspaces and decay results. With the 

 cylindrical silo the friction is equally distributed over the entire 

 inside wall surface so that the silage settles evenly. The place a 

 silo is to occupy may determine the form to select. There are 

 several kinds. Chief among these are the round, the stave, the 

 square or rectangular and the octagonal form. A square or rec- 

 tangular silo can usually be constructed within a barn with better 

 economy of space than a round silo. For this reason square silos 

 are most frequently employed within the barn and the circular 

 type when a separate building is constructed. The construction of 



349 



