THE SHRINKAGE OF MARKET HAY. — 1; 
the hay was ricked. It was also found that there was a direct 
relation between temperature and water content of the hay, the 
highest temperature occurring in the stack that contained the largest 
percentage of water. 
‘The material for rick No. 1—first-cut clover hay— was in ordinary good condition for 
stacking, and when cut into in December was found to have undergone a rather low 
fermentation, being only slightly browned and in good condition. 
The material of rick No. 2—second-cut clover hay— was greener when stacked, and 
as was to be expected, the maximum thermometer readings were somewhat higher 
than in the case of rick No. 1. The hay produced also showed a deeper brown color, 
owing to the higher temperature of fermentation. 
The highest temperature occurring in the two stacks while under- 
going fermentation was between 140° and 150° F. The investiga- 
tor’s conclusions are as follows: 
It seems unlikely that any harm to the dry matter will result where the hay has not 
exceeded a temperature of 150°F. How much higher the temperature may safely rise 
it is at present impossible to say; so much depends on the size of the rick and the 
- degree of consolidation that has taken place. The less the consolidation the more 
air there is present, and the higher the temperature is likely to rise. At the same 
time imperfect consolidation is generally to be found in ricks of small size, but on 
account of the small bulk more heat is lost by radiation, and hence there is less liability 
to fire. 
According to Hoffman, ?! the organic matter in hay is destroyed at 
a temperature of 226° F. or over. 
When spontaneous combustion occurs in clover, heat is generated in the hay, 
oxygen being taken up from the air and the organic matter transformed into carbon 
dioxid and water. The water moistens the hay, and the moistened material ferments 
because of the presence of bacteria. The fermentation also produces carbon dioxid 
and water, as well as small amounts of hydrocarbons, hydrogen, organic acids, enzymes, 
etc. Heat is also produced from the fermentation. The fermentation is more rapid 
if the clover is moistened at the beginning. However, the water produced by the 
oxidation of the material is sufficient to start it. The fermentation of the hay causes 
the temperature of 133° F. At this temperature a more violent oxidation takes place 
and the temperature rises to about 194° F. Other processes then take place which char 
‘the material and cause a slow rise in temperature to 226° F. When this temperature 
is reached, the hay rapidly heats and the charring proceeds rapidly. All these 
processes destroy at least half of the material. Theoretically the temperature may 
reach 374° F. 
According to the tests made, clover hay may become ignited at 302° F. to 392° F. 
Therefore the temperature may rise sufficiently high to cause spontaneous combustion. 
Oxygen from the air is essential to combustion. 
These experiments confirm the belief that there can be no appre- 
ciable loss by destruction of the dry matter in hay in storage when it 
has been properly cured in the field, provided the hay is protected 
from injury by rain. In other words, the natural sweating or curing 
and the resultant shrinkage of hay in the stack or barn do not involve 
2 Hoffman, F. H., Zeitschr. Spirit-ind., 1897, Nos. 35, 39, 41, 42, 45, 47,50, abs.in Biedermanns-Central- 
blatt fur Agriculturchenue, v. 27, No. 6, 1898. p. 295, 296. 
183958°—20—Bull. 873 3 
