Useful Bules and Tests. 263 



To Prepare Artificial "Starter" or Ferment for Ripening 

 Milk or Cream. 



Sterilize ten pounds of fresh, sweet skimmed or whole milk at 

 180° F. Cool to 90° F., and add sufficient dry lactic ferment to 

 secure coagulation in twenty-four hours. When coagulated, add this 

 to the extent of 10 per cent to enough sterilized whole or skimmed 

 milk to make sufficient "starter" for one day's use. Reserve each 

 day enough of this starter to prepare the starter for the next day, 

 and use the remainder for ripening the milk or cream, using for 

 this from 2 to 5 per cent, according to circumstances. Keep the 

 starter as nearly as possible at a uniform temperature of 80° F. The 

 utmost care must be taken that no germs from outside gain access 

 to the starter in any way or at any time. If this is not done, the 

 starter will rapidly deteriorate or become foul ; but with care in 

 sterilizing the milk and utensils it is not difficult to propagate a 

 starter in this way continuously for months without having it con- 

 taminated with germs of undesirable fermentations. 



To Detect Ordinary Fermentations or "Taints" in Milk. 



Procure as many test tubes one inch in diameter by five inches long 

 as there are samples of milk to be tested, and a suitable rack to hold 

 them in an upright position. Wash and rinse the tubes thoroughly and 

 sterilize them by boiling in water for thirty minutes or by exposure to 

 live steam in a sterilizing oven for fifteen minutes. After sterilizing 

 they may be allowed to drain dry and then should be kept covered till 

 wanted. When wanted for use the tubes should be filled one-half to 

 two-thirds full with the suspected milk, closed with a piece of glass or 

 plug of cotton and placed in the rack in water kept as nearly constant as 

 possible at 100° F. In from three to four hours the samples may be 

 inspected without shaking or stirring. Gaseous fermentations will be 

 manifested by the appearance of bubbles of gas upon the surface or 

 throughout the mass, souring fermentations by coagulation of the milk 

 and putrefactive fermentations or "taints" by various odors manifest to 

 the nose when the covers are removed. The samples should be kept 

 for at least twenty-four hours and examinations made at frequent 

 intervals. 



The Wisconsin Curd Test. 



This test is used for the same purpose as the fermentation test 

 described above, and is made as follows : Procure as inany covered 



