COVERED PAIL TO EXCLUDE FILTH FROM MILK. 



115 



18 the total number in the fresh milk was 30,250, and in the 

 same sample after fifty hours there were 248,750,000; while 

 on November 21 the number in the fresh milk was 3,788, and 

 in the same milk after fifty hours it was 1,258,000,000. vSim- 

 ilarly in the samples from the covered pail, in the fresh milk 

 on November 18 the total number of bacteria was 4,750, and 

 on November 19 it was 13,400; but in the same samples after 

 fifty hours the number in the former had increased to 1,121,- 

 000,000, while in the latter it was only 15,916,000. Again, 

 on November 18 the number of bacteria in the fresh milk from 

 the open pail was over six times as large as that for the 

 covered pail, but after fift}' hours the number in the latter 

 sample was nearly five times that in the former. 



THE RELATION OF THE GERM CONTENT TO THE KEEPING 

 PROPERTIES OF THE MILK. 



In the samples of milk included in Table 60 above, tests 

 w^ere made of the percentage of acid in the milk that had been 

 kept for fifty hours, and the length of time until the samples 

 curdled was noted as closely as possible; in some cases the 

 curdling occurred during the night, so that the exact time 

 could not be ascertained. The results of these observations 

 are given in the table below. 



Table 61. 

 Perce7itage of acid hi milk kept for ^o hours, and length of time 



until curdling. 



Date of Test. 



November 15, 

 November 16, 

 November 18, 

 November 19, 

 November 20, 

 November 21, 

 November 22, 



Average, 



Perctg. of Acid in 

 Milk at 50 Hours.* 



Time until 



CURDLED. 



(LI "^ 



E P. 

 §0 



.27 

 .29 



.67 

 .56 



• 43 



• 53 

 .37 



• 44 



Hrs 

 26 



33 

 o 



4 



2 



12 



22 



* Samples were kept at constant temperature of 7o°F. 

 t These samples curdled during the night. 



