174 STATE BOARD OF AGRICJJLTURE. 



for their source. Besides the direful effects of water in the conveyance of disease, 

 there are the numerous serious fermentations which may be caused by the micro- 

 organisms in the water supply. Traces of sewage, filth, or dirt, may be in the 

 water, consequently the water may be as undesirable as the substances found 

 in it. 



Vir. AERATION OF MILK. 



The discussion concerning the aeration of milk is becoming a thing of the 

 past. Practices are becoming quite uniform. Our readers are more or less 

 familiar with the work of Special Bulletin No. Ifi, of this Station. We mean 

 to quote a few paragraphs which will place before the reader some of the 

 essential points concerning this phase of milk management. 



"If agitation of milk therefore aids af-ration and if during the few moments 

 immediately after milking the interchange of gases between the air and milk is 

 greatest, it follows that where milking is in process the air must be pure, other- 

 wise the foulness of the air will be incorporated in the milk. Milk absorbs 

 gases. What must be the condition of the air of a stable in which all sorts of 

 fermentations are going on and in which are odors of diverse kinds? These 

 obnoxious substances are in the air and must pass into the milk with the air. 



"In addition to milking, frequently the milk is further agitated in the stable 

 by passing it from pail to pail or even straining it and also sometimes aerating 

 it. Such methods are rightly condemned and the reasons for such condemnation 

 are conclusive. Milking and the handling of milk should be carried on in pure 

 air. It is sometimes the practice of milk producers to pour milk directly from 

 the milking pail into a ten gallon can. From the foregoing even this must be 

 considered reprehensible, for filling the can excludes the oxygen, and, if the 

 milk is not cooled, a temperature most suitable for the development of germ 

 life is present — conditions, in short, which favor harmful fermentations. This 

 is why there are recorded so many cases of poisoning as due to the improper 

 care of the milk, eliminating the factor, filth, a common evil. 



"It has long been known that animal odors and taints may be removed by 

 atiration. Proper aeration will do it; however, aeration and cooling must not 

 be confounded in this matter. Cooling apparently removes odors and taints, but 

 such disappearances are due to the chilling of the milk, under which condition 

 the milk gives up the volatile substances with reluctance, doubtless owing to the 

 reduced power of volatility of the substances themselves when cold. When 

 such odors and taints are removed by aeration the removal is permanent unless 

 they are generated by bacteria which continue to grow after aeration. Odors 

 and taints may be due to any one of the following causes. 



1. Absorption of gases from the air by the milk. 



2. Physiological processes of the cow. 



3. Disease processes of the cow. 



4. Bacterial growth in the milk. 



5. Introduction of odoriferous substances into the milk. 



"Odors in the air emanate from fermentations, foods, etc.; aromatic substances 

 are likely to pass through the body and be secreted in the milk; a high tempera- 

 ture in an animal is likely to reveal itself in the milk; and frequently sufficient 

 filth gets into the milk to give it a distinct flavor — all of these or any one of 

 these causes may be the immediate producer of odor or taint. 



"How aeration should be conducted is a matter of considerable importance, 

 consequently we have added a few suggestions: 



1. Aeration should be conducted at body temperature. 



2. Aeration should be carried out over the most extensive surface possible 

 and as slowly as possible. 



3. Aeration should take place only in a pure atmosphere. 



4. Aeration is best accomplished immediately after milking. 



5. Aaeration should precede cooling. 



6. Aeration and cooling simultaneously conducted cannot yield the most 

 satisfactory results." 



VIII. THE COOLING ANp THE KEEPING COOL OF MILK. 



No one factor will contribute so much to the welfare of the milk producer 

 as a knowledge of cooling milk and its real significance, for in this process we 



