82 BUTTER-MAKING. 



fits into a small round tin tank, which is kept about two-thirds 

 full of water. The temperature of this water can be con- 

 trolled by means of a lamp kept burning underneath, or by 

 the use of steam. The milk from the different patrons is 

 put into the glass tubes, and these tubes numbered so as to 

 indicate to which patron each belongs. The temperature 

 should be kept at about 104 to 106 F. for about six hours. 

 Then the tubes are taken out, the milk shaken, and the appear- 

 ance, smell, and taste of the milk noted. The tubes are warmed 

 again for about another six hours, when they are again examined. 

 If any samples contain a preponderance of abnormal ferments, 

 the fact will usually appear in less than eighteen hours. If 

 milk does not coagulate in twelve hours, or become abnormal 

 in some way, it is supposed to be good. 



The special apparatus mentioned above is not absolutely 

 essential, nor is the temperature employed considered by the 

 authors to be the most suitable to give reliable results. Ordi- 

 nary sample jars can be used, instead of specially prepared tubes. 

 After the milk has been placed in the jars they can be kept 

 in any convenient place, at a temperature of about 98 F. 

 The best place to keep them is in a vessel containing water, 

 the temperature of which can be controlled. 



Wisconsin Curd Test. This test consists of taking some 

 milk in a jar and adding about ten drops of rennet, which 

 coagulates the milk. The sample is allowed .to stand until 

 the curd hardens, then it is cut into small pieces with a case 

 knife; the whey is drawn off, and the curd allowed to stand 

 at a temperature of 98 F. If there are any undesirable forms 

 of bacteria present, they will reveal themselves by developing 

 small holes in the curd, usually accompanied by a bad odor. 



This test is a very ingenious one for cheese-making. In 

 butter-making the Gerber Fermentation Test, or a similar one, 

 is more convenient. 



4. Grading Milk by Heating. This test is not used very 

 much in creameries; but in cheese factories the heating of 

 milk in order to ascertain its suitability for cheese-making is 



