ENSILAGE. 407 



grass were subjected to a high temperature, by means of steam, 

 for instance, and sealed up in an air-tight box at that tem- 

 perature, it might be kept green and moist for any length 

 of time. This is what is done in the tinning of peas and 

 other vegetables. If deprived of air, or rather the oxygen con- 

 tained in the air, or if surrounded by any gas which does not 

 contain free oxygen, grass or other green fodder can be kept 

 moist and fresh for a very long time. This is what is 

 done in a silo. When green fodder is thrown into a silo, 

 and pressed down so as to diminish as much as possible the 

 air space w^ithin it, the amount of oxygen is very small in 

 comparison with the mass of solid material; and if the walls of 

 the silo are air-tight, and the surface of the heap covered over 

 with some impervious covering, and the whole subjected to 

 continuous pressure, the limited supply of oxygen contained in 

 the substance and the interstices of the fodder is verv soon 

 used up by the ferments, and when that point is attained the 

 fermentation ceases. A certain quantity of alcohol is found, 

 determined by the quantity of oxygen originally present, and 

 some of this may be converted into acetic acid, &c. ; but as the 

 oxygen is used up, the carbonic acid formed at the same time 

 goes on increasing in amount, until the oxygen is exhausted, 

 and carbonic acid has taken its place. The ferments are thus 

 practically suffocated, and so long as the carbonic acid does not 

 get away, and air take its place again, the fodder is preserved 

 from fermentation and the other putrefactive changes referred 

 to. One great object to aim at in filling a silo is therefore to 

 diminish the quantity of air space. If the stufl* to be ensiled 

 is hard and reedy, such as oats, the quantity of air contained 

 in the tubes of the straw is so great, that the ferments are able 

 to live and work for a comparatively long time before their 

 supply of oxygen is used up. The fermentation will not stop at 

 the alcoholic stage, but it will go on to the formation of acids, 

 and part of it will putrefy. The ensilage will be of a sour taste, 

 and have a putrid smell, and there will be a considerable loss 

 of feeding material on account of the extent of the fermentation. 

 If, bef(jre ensiling, the green straw had been passed through 

 a chaff-cutter, it would have i)acked much closer, and 

 cnished much easier, and preserved much better. If, on the 

 other hand, the crop is grass, especially meadow grass or soft 

 grasses, or an aftennatli, with much leaf and little stem, the 

 stuff })acks together Hat and tirni, allowing of almost no 

 intiTstitial air, anrl the ensilage formed is sweet of smell and 

 taste, with only a trace of alcoholic odour, and the whole colour 

 and characters of the j)lants are retained almost unchanged, 

 luisilage of this kind well weighted conies very near the perfect 

 standard. 



