268 



STATE BOARD OF AGRICULTURE. 



of these two gases, oxygen and nitrogen only, as in air, the oxygen should exist in the 

 ratio of 33.9:66.1 to nitrogen according to Bunsen: 

 10.29, 14.09, 14.70, 11.86, 8.06, 15.26. 



There is only one possible way of explaining the presence of oxygen in the gas- 

 content of milk. It is barely possible that some oxygen may be accounted for by its 

 creeping in through its adherence to the mercury and walls of the container ; however, 

 when an attempt is made to secure it in pumping in the absence of milk not an appre- 

 ciable trace of gas can be obtained. This ought to demonstrate that the oxygen is. 

 inherent in the milk. 



It may be also well worth considering the fact that the cow used for this purpose 

 received very little exercise; she was confined to her stall most of the time. There 

 may be some relation existing between the carbon dioxide and the oxygen of milk due 

 to the amount of exercise of the animal caused by a reduction in the metabolism of the 

 body cells. I call attention to this as a possible answer to the variation in the gas 

 constituents of the milk. 



After ascertaining the gas-content of milk before it has been exposed to the air, it 

 became necessary, in order to fully understand the changes in the gas-content of 

 milk, to next study the gases of milk immediately after milking. 



V. ANALYSES OF THE GAS-CONTEXT OF MILK DIRECTLY AFTER MILKING. 



The milk was secured in the ordinary way by milking into an open receptacle, thus- 

 allowing the milk to become exposed to the air in an open stream from the milk-duct to 

 the receptacle; further, there was the churning action taking place as the streams 

 impinged against the surface, which also exerts a marked influence in bringing the air 

 in contact with the milk, because by this method much air is carried down into the 

 milk. It has been found that it takes a few minutes after milking before the perceptible 

 air bubbles rise to the surface. The surface of the milk in the receptacle also offered 

 an opportunity for a considerable interchange of gases between the milk and the air. 



Immediately after milking the milk was taken to the laboratory and placed in the 

 same container as in the previous analyses, and the gas was obtained in identically the 

 same manner. 



Thorner (14) has made some analyses of the gas obtained from milk immediately 

 after milking, but he employed heat to drive off the gases. The amount of gas which 

 he obtained was much larger than in our case and his results were usually higher in 

 carbonic acid gas, possibly due to his methods. I take the liberty to quote several 

 of his analyses of milk directly after milking: — 



(14.) Loc. cit. 



