Useful Rules and Tests 357 
Usually it is necessary to propagate the mother starter two or three 
times before the flavor of the commercial culture, which is often very 
disagreeable, will disappear. 
A starter may be carried two to four weeks before it goes “off.” 
Often it is carried several months, and often less than two weeks. This 
depends almost altogether on the carefulness of the operator. 
To Detect ORDINARY FERMENTATIONS OR “Tarints” 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. 
Tun Wisconsin Curp Trst 
This test is used for the same purpose as the fermentation test 
described above, and is made as follows: Procure as many covered 
pint glass jars as there are samples of milk to be tested and clean and 
sterilize them as described above. Fill each jar two-thirds full of the 
milk to be tested, label them plainly and put them up to the neck in 
a tub or vat of water heated to 98° F. When the milk has reached the 
temperature of the water add ten drops of rennet extract to each jar, 
and mix it with the milk by shaking the jar. Allow the jars to stand 
until the curd is firm and then cut the curd finely with a case knife. 
When the curd has settled pour off the whey and allow the curd to 
settle again till a second portion of whey can be removed. The best 
tests are made when the removal of whey is as complete as possible. 
The jars containing the curd are then covered and again placed in the 
