ILLINOIS STATE DAIRYMEN'S ASSOCIATION. 79 



T. J. BuRRiLL furnished the following paper, which 

 was received too late to come under its appropriate head : 



FERMENTATION AND PUTREFACTION OF MILK. 



In early times, with peoples as with individuals, the changes 

 which occurred in such a substance as milk when allowed to stand for 

 some time excited no curiosity; stirred no one to inquire why the phe- 

 nomena presented took place. If any thought is given to the subject 

 a satisfactory conclusion is reached when it dawns upon the mind 

 that milk sours because it is its nature to do so ; it becomes unpleas- 

 antly odoriferous because it could not continue otherwise. From 

 this low beginning it is a long way and by no means one without 

 difficulties to the full knowledge now possessed by some investigators 

 of the changes and their causes which take place so persistently in 

 so common an article as cows' milk. It is possible that some whose 

 business makes them more especially interested do not yet appreci- 

 ate the fact that all these ordinary changes arise from the action of 

 living organisms altogether foreign to the constituents of the milk 

 itself. For a long time the idea has been current that in such organic 

 compounds changes arose through spontaneous chemical agencies, 

 that the oxygen of the air is the chief factor in the production of the 

 results observed. This was supposed to be confirmed by the fact that 

 the air being driven out by heat the changes came later, or upon ex- 

 cluding the air, as by heating and canning, they occurred not at all. 

 But it has been demonstrated that pure air may have free and abund- 

 ant access to putrescible compounds, such as milk, without the latter 

 becoming in the least affected. There is no souring, no fermentation 

 or decomposition of any kind. The milk retains its freshness and 

 purity for an indefinite length of time ; only the steady dessication 

 causes the least chaijge. The conditions are that the air be entirely 

 freed from suspended particles and that the vessels be absolutely 

 cleaned, or heated to a sufficient degree to kill all living atoms and 

 their germs. It has been shown that air sufficiently filtered 

 through clean cotton, wool, or even allowed to settle in a perfectly 

 quiet reservoir is inert — absolutely incapable of producing fermenta- 

 tion or decay. Under such circumstances temperature has no effect. 

 The protected liquid is preserved just as well at 90° Fahr. as at the 

 freezing point. A liquid keeps its fresh condition as long as a solid 

 body from which all water has been evaporated. 



