36 UNIVERSITY OF WISCONSIN STUDIES 
The process of pasteurization not only frees milk from the 
danger of transmitting tuberculosis but at the same time it 
frees it from the danger of transmitting the other diseases 
which have been observed to have been occasionally so trans- 
ferred. Accordingly pasteurization is coming to be recog- 
nized as the simplest and most efficient protection against the 
spread of disease germs through milk supplies. 
THE PROBLEM OF CLEANLINESS 
Even under most favorable conditions it is difficult to pre- 
vent limited amounts of foreign matter from getting into milk. 
On the other hand, the consumer insists that the milk shall 
be as clean as practicable. Fortunately the amount of soluble 
foreign matter which finds its way into milk is very slight 
and the white color of the milk forms a background against 
which any insoluble matter present stands out distinctly. 
The amount of insoluble dirt actually present in milk as it 
ix delivered to the consumer naturally varies considerably.” 
The present available data suggest that it rarely amounts to 
more than five milligrams per quart or roughly five parts per 
million while the average is nearer one part per million. 
The Wisconsin Sediment Tester? is a convenient device for 
collecting upon a cotton disk the insoluble dirt from a pint 
of milk and has proven a satisfactory instrument for this 
purpose. At the Chicago Department of Health this method 
has been made ronghly quantitative by preparing test disks 
from samples of milk containing weighed amounts of dirt.” 
At the University of Illinois the standards for quantitative 
examinations of sediment in milk have been still further 
perfected until it is believed that the weight of the insoluble 
dirt in milk may be quickly determined with an accuracy 
rivaling that obtained by any other available means. 
The standards for this purpose are prepared by powdering 
“CH, N. Parker, City Milk Supply, p. 256. 
#S. M. Babcock and E. H. Farrington, New and Improved Tests of Dairy 
Products, Bulletin 195, Wis. Agr. Exp. Sta., 1910. 
38, O. Tonney, Report of the Municipal Laboratory, Department of 
Health, City of Chicago, 1907-1910, p. 25. 
