CHAPTER VIII. 

 TESTING THE PURITY OF MILK. 



149. The Wisconsin curd test. Cheese makers are often 

 troubled with so-called floating or gassy curds which 

 produce cheese defective in flavor and texture. These 

 faults are usually caused by some particular lot of milk 

 containing impurities that cannot be detected by ordi- 

 nary means of inspection. The Wisconsin curd test is 

 used to detect the source of these defects and thus enable 

 the cheese maker to exclude the milk from the particular 

 farm or cow to which the trouble is traced. This test is 

 similar in principle to tests that have for many years 

 past been in use in cheese-making districts in Europe, 

 notably in Switzerland, 1 but was worked out independ- 

 ently at the Wisconsin Dairy School in 1895 and has 

 become generally known as the " Wisconsin Curd Test" 

 from the description of it in the report of the Wisconsin 

 experiment station for 1895. 2 



The apparatus used for the test was greatly improved 

 in 1898, and a description of the improved test is given 

 in bulletin No. 67 and the annual report of this station 

 for 1898, 3 from which source the accompanying illustra- 

 tions are taken (see Figs. 45 and 46). 



150. Method of making the test. Pint glass jars, thor- 

 oughly cleaned and sterilized with live steam, are pro- 



1 Herz, Unters. d. Kuhmilch, Berlin, 1889, p. 87; Siats, Unters. landw. 

 wicht. Stoffe, 1897, pp. 129-131. 



2 Twelfth report, p. 148. 



3 Fifteenth report, pp. 47-53. 



