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STATE BOARD OF AGRICULTURE. 



III. During aeration the carbon dioxide of the purnped gases dropped still 



farther to an average of 40.57 1-6% over glass, 35.832% over tin, 42.328'* 

 over copper, and to 25.805% through glass wool; the oxygen increased to 

 an average of 20.586% over glass, 20.55% over tin, 17.256% over copper and 

 through glass wool to 20.805%. 



IV. Air confined over sterilized milk indicates no interchange of gases. 



V. Most micro-organisms in milk generate carbon dioxide and absorb oxygen. 

 VI. Milk fresh from the cow and confined in a flask consumes the oxygen 



and liberates carbon dioxide upon fermentation . 

 VII. When antiseptics are used in fresh milk, oxygen is very slowly absorbed 

 and no appreciable quantities of carbon dioxide are given off. 

 VIII. Free carbon dioxide in amounts of 100%, 96.5%, and 62.9% have a marked 

 restraining action on bacteria and in some cases an inhibitive action. 

 IX. A percentage of 32.9% of carbon dioxide stands on a border line where 



the action of this gas gradually disappears. 

 X. When free carbon dioxide is made to act upon sterilized and inoculated 



milk the restraining influence is also very noticeable. 

 XI. When bacteria are grown in bouillon under the influence of carbon dioxide, 

 this restraining action is very prominent. 

 XII. Free carbon dioxide has a direct influence upon the character and rate of 

 milk fermentations induced by specific micro-organisms. 



XIII. Carbon dioxide in its free condition corresponds very closely in its action 



upon bacteria with carbon dioxide as it exists in milk, and it constitutes 

 about the same percentage of the pumped gases. 



XIV. Hydrogen has practically the same action on bacteria as carbon dioxide. 

 XV. The nitrogen or residual gas resulting from the absorption of oxygen from 



air by means of alkaline pyrogallate is not so detrimental to the develop- 

 ment of bacteria as free carbon dioxide or hydrogen. 

 XVI. Lactic acid has a varying influence upon the development of different 

 micro-organism s . 

 XVII. The acidity of milk is influenced by the aerobic and anaerobic conditions 



under which micro-organisms are cultivated. 

 XVIII. Confined milk does not show a decrease in acidity after milking. 

 XIX. Milk exposed freely to the air decreases in acidity for a few hours after 



milking then the acidity rises rapidly. 

 XX. Carbon dioxide is one factor which keeps up the acidity of confined milk 

 with phenolphthalein as an indicator. 

 XXI. Bacteria do not thrive so well in unaerated milk without exposure as in 



exposed milk. 

 XXII. The germicidal action of milk is not influenced by the aerobic or anaerobic 

 conditions. 

 XXIII. The aeration of milk does not reduce the number of bacteria directly. 



A review of the summary immediately brings before us striking evidence that under- 

 lying aeration of milk are to be found indisputable data fundamentally important 

 which may lead us to definite conclusions. In the determination of the gas-content 

 of milk, the rapid decrease of carbon dioxide and the increase of oxygen content at 

 once demonstrates that there is a considerable change in the gases of milk through 

 aeration. There is to be no sanitary significance attached to this interchange of 



