no STORRS AGRICULTURAL EXPERIMENT STATION. 



The dirt collected in this way of course consisted chiefly of 

 insoluble materials, because most if not all of the soluble mate- 

 rial would be dissolved by the use of so much warm water as 

 is necessary to wash the milk out of the dirt residue, and in 

 solution would be thrown out of the separator or would pass 

 through the filter paper. The table above gives the results of 

 a series of tests made as above described. 



The figures in the table show that on the average there was 

 in a liter of milk from the open pail o. ii gram of dirt, and 

 from the covered pail, 0.04 gram; indicating that 63 per cent, 

 of the dirt falling into the former pail was kept out of the 

 latter by the cover. 



The amount of dirt falling into the open pail was not large 

 in any case. The weights given in the table are for dry dirt, 

 and for insoluble material only; but the total quantities of dirt 

 in the milk were probably not much larger than these. In milk 

 obtained in dairies where the sanitar}' conditions are poor the 

 amount of dirt is very much larger. These tests were made 

 with cows kept in a stable where the conditions of cleanliness 

 are decidedly better than those of the average dairy barn. 

 With a few exceptions the milk did not look dirty as it stood 

 in the pail. 



The reason why the percentage of dirt in the covered pail 

 was as large as was found can probably be explained by the 

 fact that the amount of dirt falling from the cow is greatest 

 directly over that side of the pail on which it is necessary to 

 have the opening in the cover; so that the ratio of the amount 

 of dirt falling on the opening in the cover to the total amount 

 falling upon the pail was probably greater than the ratio of 

 the opening in the covered pail to the exposed surface of the 

 open pail. 



THE RELATION BETWEEN THE AMOUNT OF DIRT IN THE MILK 

 AND THE KEEPING PROPERTY OF THE MILK. 



Tests were made of the keeping properties of the milk drawn 

 into the two kinds of milking pail, both pails having been 

 thoroughly sterilized by steam before the milking. Repre- 

 sentative samples from each pail were placed in sterile vessels, 

 and were kept under the same conditions of temperature, etc., 

 until the)^ had curdled, and the lengths of time until the curd- 

 ling of the samples were compared. As soon as the first sample 



