EXPERIMENT STATION BULLETINS. 



269 



In considering the work of Thinner it is necessary to have in mind the method 

 employed by him in securing gas from milk. Inasmuch as we had reached the con- 

 clusion that a high temperature increased the amount of gas obtained from a definite 

 quantity of milk and that probably the carbon dioxide is with difficulty released upon 

 pumping, issue must be taken with the results of Thorner. Further it has been 

 demonstrated that other gases as hydrogen sulphide may be generated by boiling 

 milk. 



The high percentages of carbon dioxide indicates that heat may have facilitated the 

 dissociation of carbon dioxide whether in solution or loose combination to that extent 

 that a higher percentage of carbon dioxide and a lower percentage of oxygen were the 

 results. It is well known carbon dioxide is with difficulty liberated in the presence of cer- 

 tain salts as CaC0 3 , Na 2 HP0 4 , and others (Setchenow). At any rate as our tables 

 will show, Thorner's average of percentages differs materially from ours, although it 

 falls considerably below milk which has not been exposed to the air. 



Blyth (15) in his analysis of the gas-content of milk immediately after milking 

 obtained a very low amount of carbon dioxide. His analysis is, 



Carbon dioxide 06 cc. 3.27 per cent. 



Nitrogen 1.42 " 77.60 " " 



Oxygen 35 " 19.13 " " 



The results obtained by him in no way can be reconciled with the results of 

 Thorner or with the results which we secured. He has shown the possibility of the 

 development of carbon dioxide after fermentation has begun, but it appears incredible 

 that he should have gotten such a low percentage of carbon dioxide from fresh milk. 



Our analyses are as follows: — 



TABLE II. 



Sample. 



Date 



Began milking at 



Completed milking at 



Began pumping at 



Completed pumping at 



Temperature when pumping — 



Barometric pressure in mm 



Total gas in c. cm 



Carbon dioxide in c. cm 



Per cent, of carbon dioxide 



Oxygen in c. cm 



Per cent, oxygen 



Residual gas in c. cm 



Per cent, residual gas 



Nov. 29th. 



7:35 a. m. 



7:45 a. m. 



9:00 a. m. 



10:15 a. m. 



37.6° 



088.0 



0.62 



3.82 



59.31 



.91 



13.79 



1.78 



26.9 



II. 



Nov. 30th. 



7:25 a. m. 



7:35 a. m. 



8:35 a. m. 



9:35 a. m. 



38° 



690.63 



6.84 



3.78 



55.33 



.86 



12.06 



2.19 



32.01 



III. 



Dec. 2d. 



7:30 a. m. 



7:40 a.m. 



8:30 a.m. 



9:30 a.m. 



38° 



690.03 



5.96 



3.47 



58.27 



.84 



14.17 



1.64 



27.56 



IV. 



Dec. 4th. 

 7:35 a.m. 

 7:45 a. m. 

 9:00 a. m. 

 10 :15 a.m. 

 38° 

 096.6 

 2.70 

 1.78 

 66.1 



.32 



11.89 



.59 



22.01 



Dec. 6th. 

 7:35 a. in. 

 7:45 a. m. 

 8:40 a. m. 

 9:40 a. m. 

 37.8° 

 098.6 

 6.64 

 4.35 

 65.65 

 .727 

 10.96 

 1.55 

 23.39 



VI. 



Dec. 7th. 



7:45 a. m. 



7:55 a. m. 



8:50 a.m. 



9:50 a. m. 



37.5° 



692.84 



5.5 



2.93 



53.28 



.85 



15.57 



1.71 



31.15 



In the study of the above tables it will be found that the percentage of the gases in 

 milk have undergone a change in the milking process itself. The carbon dioxide 

 has been reduced and the oxygen increased. The six analyses of the gas-content of milk 

 before exposure to the air give the following percentages in carbon dioxide: 

 80.58, 78.35, 81.73, 81.97, 80.16 and 86.19. 



The average of the six analyses is 81.49% per cent. 



(15.) Foods, Their Composition and Analysis, 4 Ed., p. 251. 



