IS ENSILAGE A SUCCESS? 137 



the opportunity for fermeDtation. If the side-walls of the 

 silo are not air-tight, heavy weighting becomes a necessity. 

 Yet it must be remembered, that your weights added to 

 cover are simply for use on the upper five feet in depth of 

 the ensilage. That part of the contents of the silo — at 

 40 pounds to the cubic foot, which is a low estimate for 

 corn — exerts a pressure of 200 pounds to the square foot upon 

 all that is below, and this increases toward the bottom. 

 Where the forage itself is worth two or three dollars per ton, 

 I advise weighting the cover with from 50 to 200 pounds to 

 the square foot. Fry of England says 100 pounds. Goifart 

 has been already quoted as in favor of 200 pounds or more ; 

 he has written, — " the greater pressure, the surer the suc- 

 cess." Screws, levers and mechanical devices have been 

 tried, but none have succeeded very well. A dead weight 

 or following pressure is needed. Hence stones, loose or in 

 barrels or boxes, concrete blocks, sand bags, earth and sand, 

 and barrels of water (where protected from freezing) have 

 been successfully used. Water barrels have been arranged 

 so as to fill and empty with pipes and syphons. Where 

 grain is purchased in quantity, sacks of bran and like mate- 

 rial may be piled on the cover, and storage is thus provided 

 as well as pressure. 



If a silo is very deep, the pressure upon the material near 

 the bottom may become so great as to express the liquid 

 fi'om the mass. All below twenty-two feet depth sustains a 

 pressure of over a thousand pounds to the surface foot. 



V. — What are the Changing Processes in the Silo? 



To tell exactly what goes on in the silo after it has been 

 filled, closed and weighted is impossible. There are cer- 

 tainly chemical changes, some of which are known. I ven- 

 ture the opinion, that with all the careful investigation that 

 has been made, the chemist cannot yet explain all the pro- 

 cesses of the silo, and I do not venture in this presence to 

 describe technically the chemical conversions that are known 

 to occur. 



Fermentation there is, commencing soon, rapidly increas- 

 ing unless arrested. And with fermentation heat is pro- 

 duced. Fermentation is but another name for combustion. 



