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 
stnall 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 
