22 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE. 
substances. As ordinarily practiced, aeration has a double purpose — 
first, to air the milk ; and second, to lower its temperature. Eussell 
(10) reports "the method certainly has no disadvantages." It 
should be borne in mind also that feed and barn taints once re- 
moved are removed permanently by the process. Marshall says (9) 
"it is best accomplished immediately after milking. "^ According 
to Ernst (0), "the aeration of milk permits the escape of carbonic 
acid, hydrogen, and sulphid of hydrogen, and supplies the milk with 
air so that in all probability the development of certain bacteria is 
checked, which otherwise, if the milk had been filled in containers 
in a warm and unaerated condition, would have imparted" to the 
milk a sharp disagreeable taste and odor ; the milk would have been 
' smothered.' " 
PLACE TO USE THE AERATOR. 
In aerating milk it should be borne in mind that the same condi- 
tions which favor the escape of odors which the milk contains when 
drawn from the cow are also conditions which permit the milk to 
become tainted with odors from the outside. For this reason, aera- 
tion should take place in a milk room in which the air is free from 
bad taints or dust, and which is well ventilated. 
GOOD FLAVORS AND ODORS IN MILK. 
It is important that milk have a good flavor and a good odor. It 
is probable that some flavors and odors constantly present in milk in 
time cease to be objectionable to the individual and are taken as a 
matter of course. In some alfalfa sections of the United States the 
so-called alfalfa taste is general in milk and in these sections is ac- 
cepted without comment. 
The work has shown that fine-flavored milk is an individual char- 
acteristic of some cows. It may be that whole herds of cows giving 
milk of desirable flavor will be assembled in the future, and the 
effort made to fix and perpetuate this desirable characteristic by 
breeding and selection. 
Preventive measures are always best; therefore dairymen should 
endeavor, first, to have cows and barns clean; second, to have cow 
stables properly ventilated; third, to feed after milking those mate- 
rials likely to taint milk; and fourth, to decrease feed and barn taints 
by proper and immediate aeration. Finally, prompt cooling and 
storing of milk at a low temperature will retard the development of 
odors from bacterial action. 
As stated before, the cows used in these experiments produced daily 
approximately 10 pounds of milk each. It is possible that with cows 
of greater or less production different amounts of silage might be 
fed with varying results as regards intensity of the flavor imparted 
