PRESERVATION <>F Fool) PRODUCTS FROM BACTERIA. 315 



like those of the North Sea and the Austrian Alps, and it is 

 occasionally used the world over. In its preparation the grass 

 is built up into a stack or rick, 13 to 16 feet high and 16 

 to 24 feet in diameter. It is well trodden down, but not 

 packed so firmly as in the last method, and the whole stack is 

 thatched so as to shed the rain. In such ricks a spontaneous 

 fermentation sets up and the mass becomes heated. Here 

 too the temperature frequently rises as high as 160 F., but it 

 does not rise much higher, and there is no danger of spon- 

 taneous combustion. The rick is not opened, but the hay 

 remains in the mass until the farmer wishes to use it. It is 

 immaterial whether the hay is rained upon or not, and this 

 makes the process especially adapted to rainy districts. 



The fermentation which takes place in these ricks produces 

 a great change in the nature of the product. It becomes a 

 firm, dry mass, of a pale or dark brown color, or may, if the 

 heating is too great, be almost black. It has developed at the 

 same time an aromatic odor which resembles freshly baked 

 bread. There develops also a large amount of lactic and 

 butyric acids, the amount of lactic acid being as high as 7 per 

 cent, and the butyric acid over 2 per cent. These acids are 

 derived chiefly from the carbohydrates, as is shown by the 

 great reduction in the amount of these bodies in the drying 

 hay. A considerable part of the nitrogen material is also lost, 

 the total loss in the hay being about 14 per cent. Whether 

 this fermentation is wholly due to enzyme-like bodies which 

 produce the rapid rise of temperature, or whether bacteria 

 play a part is not known. The production of the acids has 

 hitherto been attributed to bacteria, but without any actual 

 demonstration of their presence. 



It should also be noticed that hay prepared by the simple 

 process of sun-drying undergoes a subsequent fermentation of 

 a limited extent, and of a nature which is doubtless closely 

 akin to that just mentioned. After the sun-dried hay is stored 



