COVERED PAII. TO EXCLUDE FILTH FROM MILK. 



Ill 



had curdled, however, portions were drawn from both samples 

 and the percentage of acid in them was determined by the use 

 of Farrington's alkaline tablet solution. The results of these 

 tests are given in the following table: 



Table 58. 



Time of ciwdling, and pej'centage of acid in both samples when 



the first one had curdled. 



In the first test in the table both samples curdled in the 

 same length of time, and the percentage of acid was practicall}^ 

 the same in both. The same is true of the test on October 

 28th. In all the other tests the sample from the covered pail 

 curdled first, the average difference in time for the whole eight 

 tests being seven hours. The percentage of acid in the samples 

 from the covered pail was also greater in each case, except 

 those already noted, than in those from the open pail, the 

 average difference being .12 per cent. 



It has already been seen that in the average of fourteen tests 

 the milk from the covered pail contained only about 37 per 

 cent, as much dirt as that in the open pail. The figures above 

 show that in the average of eight tests the milk from the 

 covered pail curdled seven hours sooner and at the time of 

 curdling contained .12 per cent, more acid than the milk from 



