COVERED PAIL TO EXCLUDE FILTH FROM MILK. II9 



the smallest the dirt contained a large proportion of manure 

 which became more or less disintegrated and dissolved in the 

 milk and could therefore pass through the strainer. 



According to the results given in Table 57 the amount of dirt 

 in the milk from the covered pail was in the average of four- 

 teen tests but 37 per cent, of that in the milk from the open 

 pail. That is, 63 per cent, of the dirt that would fall into an 

 open pail was kept out by the cover, whereas in the tests here 

 described only 47 per cent, was removed by straining. 



NUMBER OF BACTERIA IN THE MILK. 



The total number of bacteria and the number of acid species 

 and liquefiers in both samples of milk were determined in the 

 fresh milk and again in several of the samples after they had 

 been kept for fifty hours. The results of the tests are given in 

 Table 63 above. 



In every test but one the total number of bacteria in the 

 strained milk was smaller than that in the milk not strained, 

 the average being about 1 1 per cent, less in the former. The 

 numbers of acid producing bacteria and liquefiers were in some 

 tests larger and in others smaller in the strained milk, the 

 number of acid bacteria averaging about 17 per cent, less than 

 in the milk not strained. In the milk after fifty hours the 

 number of acid bacteria was very much larger in the strained 

 milk. 



If Table 60 is compared with Table 63 to determine the 

 relative value of the straining and the use of the covered pail, 

 it will be seen that the covered pail appears to be somewhat 

 superior. The cover reduced the average number of bacteria 

 from 9,500 to 6,700 per cubic centimeter in fresh milk, whereas 

 the straining had considerable less influence, reducing it from 

 11,400 to 10,100 only, indicating that straining through cheese 

 cloth after milking is not so efficient a means of preventing 

 the entrance of bacteria as using the covered pail. 



THE KEEPING PROPERTIES OF THE MILK. 



After the milk had been kept for fifty hours at a temperature 

 of 70° F. the percentage of acid was determined in both sam- 

 ples; they were then allowed to stand until the milk had cur- 

 dled, and the length of time noted. These results are given 

 in the following: table. 



