THE SOURING OF MILK. 



179 



Table XLII. shows how useless these preservatives in small 

 amounts are, and an equal effect is produced by a few degrees 

 lowering of temperature. 



The author and Miller have investigated the action of other 

 preservatives on milk ; the results at 20° C. = 68° F. were : — 



TABLE XLIII. 



The following substances had no appreciable preservative 

 effect : — Sodium fluoride, potassium acid fluoride, resorcinol, 

 phloroglucinol, phthalic acid, abrastol, sodium /8-naphthol- 

 sulphonate, and cyllin. 



The Souring of Milk.— Lactic acid is developed by the action 

 of micro-organisms on the milk-sugar, and the acidity of the 

 milk is a rough measure of this. 



TABLE XLIV. — Temperature in Degrees Fahrenheit. 



Time in Htmr^ 



10, 

 15, 

 20. 

 25, 

 30, 

 3u, 

 40, 

 45, 

 50, 

 55, 

 CO, 

 70, 

 80, 

 90. 

 lOU, 



