264 STATE BOARD OF- AGRICULTURE. 



Second Analysis. 



Carbon dioxide 87.16 per cent. 



Oxygen 1.06 " " 



Nitrogen 11.78 " " 



Amount of gas per 100 e. cm. of milk was 8.49 c. cm. Amount of milk used 77.310 

 c. cm. 



The analyses of all of these men were made directly after milking, and did not 

 extend over a time sufficient to warrant fermentation. 



Pfliiger was of the opinion that he had secured all the gas possible within one hour's 

 time and made no allowance for a slow generation of gas after the hour when sub- 

 jected to high pressure. This is not in accord with our experience, for after the first 

 ebullition of gas which takes place early in the pumping process there follows a slight 

 development of gas until fermentation sets in, when there is a marked increase. 



III. DESCRIPTION OF APPARATUS. 



For our experiments we departed from the methods used by Hoppe, Stechnow, and 

 Pfliiger, in that we endeavored to eliminate any possible chance of exposure of the 

 milk to the air. Pfliiger's method, the best previously adopted, is open somewhat to 

 criticism in that there is a possible chance of the milk coming in contact with the air 

 or being more or less churned with traces of air. His analyses, however, indicate 

 that errors of this kind scarcely made any difference, in fact, he seems to have obtained 

 about the same amounts of oxygen in his experiments as were obtained in ours. In 

 order to secure the milk from the udder of the cow without any exposure to the air we 

 employed a milking tube 6.6 cm. long attached and fitted to a piece of pressure tubing 

 80 cm. long and 5 mm. in diameter. The walls of this tube were 4 mm. thick. Over 

 the aperture of the milking-tube was placed a piece of thick rubber tubing of small 

 caliber so that it just fitted the tube. This served as a slide valve in closing and open- 

 ing the apertures. The other end of the rubber tube was attached to a glass tube 

 5 mm. bore, containing a three way stop-cock and this in turn was attached to the 

 receptacle used as a container for the milk by means of a short piece of pressure tubing. 

 This will now be described. 



The container for the milk is of the nature of a large bulb of heavy glass fixed 

 securely to a standard of wood. It has three openings all of which are closed by 

 means of a glass stop-cock at will. One of these openings is at the bottom of the 

 bulb, another directly above at the top and the other a side arm on the right 

 shoulder. The top arm consisted of a capillary tube containing a three way stop-cock 

 an inch above the bulb, and above this a cup and a male portion of a mercury over- 

 lapping glass connection. The bottom opening and right shoulder opening were tubes 

 5 mm. in diameter, fitted with two way stop-cocks. When ready for use, this bulb, 

 with a capacity of 562 c. cm., was filled with dry mercury. The side arm connected with 

 the tube extending to the milk-duct of the udder was filled with mercury as far as the 

 three way stop-cock; the remaining distance was filled completely with boiling water, 

 driving out all the air, and when driven out, all of the apertures of the milking-tube 

 were closed by means of a sliding rubber valve. When ready for drawing the milk, 

 the tip of the milking-tube was carefully inserted into the milk-duct of the udder, and 

 as the teat was pushed on the rubber valve over the apertures in the tube was pushed 

 down, thus allowing the milking-tube to be inserted without the escape or the entrance 

 of any air. When all was in readiness the three way stop-cock was so turned as to 

 allow the water to run out and the milk to take its place; then the three way stop- 

 cock was again so turned that the milk would run in the direction of the container, 

 the stop-cock of the side arm of the container was also turned on. This made, there- 

 fore, a direct connection from the udder to the container of the milk without the 

 presence of any air whatever. To draw the milk the stop-cock of the lower arm of the 

 container was turned so as to allow the mercury to escape, drawing the milk from the 

 udder as normally as it was possible. With the running out of the mercury the milk 

 entered and filled all parts of the container, so that when the mercury had all escaped 

 and the lower stop-cock turned off, the receptacle was completely filled without even 

 traces of air. 



As soon as the container was filled with milk direct from the udder it was taken to 

 the laboratory and immediately connected, by means of the mercury valve of the top 



