COVERED PAIL TO EXCLUDE FILTH FROM MILK. 



109 



with warm filtered water, and this was also poured into the 

 bowl. After that filtered water at 90° was run through in 

 sufficient quantity to wash out the greater part of the milk 

 from the dirt residue. If the bowl was running at the proper 

 speed before the milk was poured in, and if the speed was 

 maintained till the overflow had entirely ceased, there would 

 be left in the bowl a watery liquid containing the dirt from the 

 sample and a small percentage of milk; but when the work was 

 properly done there would be no fat left in the bowl to inter- 

 fere with the subsequent filtering. 



The contents of the bowl, which consisted of the dirt residue 

 and small quantities of milk, were then collected in a small 

 dish b}^ means of repeated washing, and these were filtered 

 through a filter paper which had previousl}' been dried in a 

 desiccator and weighed. In order to free the residue on the 

 filter paper frohi all trace of milk it was necessary to wash it 

 for several hours with warm filtered water. After washing 

 until "the filtrate showed no traces of cloudiness the paper with 

 the dirt was again dried in the desiccator and weighed, and the 

 weight of the dirt computed. 



Table 57. 



Diffe7'e7ice between amounts of dirt in viilk from open and covered 



pails. 



Date of Test. 



October 15, 

 October 16, 

 October 17, 

 October 22, 

 October 23, 

 November 4, 

 November 5, 

 November 15, 

 November 16, 

 November 18, 

 November 16, 

 November 20, 

 November 21, 

 November 22, 



Average, ------ o 



