ADMIXTURE OF DIRT 127 



greater or less dirt content has a great influence upon 

 the healthfulness and keeping quality of the milk; this 

 is emphasized by a study of the bacterial content of cow 

 dung. Wiithrich and Freudenreich found this to vary 

 according to the kind of feed ; the bacteria in the dung 

 of cows fed with hay appeared to be most numerous; 

 1 gramme of such excrement contained 375,000,000 

 bacteria. 



Of course the quantity of dirt in market milk differs 

 very greatly. An investigation in Hamburg showed that 

 the quantity varied from 0.0 to 183.5 milligrams per 

 liter ; on the average, there were 13.5 milligrams of dry 

 dirt in a liter of milk. In other experiments, Schmelk in 

 Christiania found an average of 11 milligrams in a liter, 

 von Hellens (Helsingfors) found only 1.79; in Berlin, 

 Renk showed the average to be 10.3; in Halle, 14.92; 

 in Leipsig, 3.8 and in Munich, 9.0. The maximum quan- 

 tity in each case was much greater than the averages 

 mentioned, although it never reached the maximum for 

 Hamburg milk. 



In Dresden the standard regarding market milk 

 states that it must not contain more than 8 milligrams of 

 dirt per liter. 



In Denmark there are no general regulations con- 

 cerning the dirt content of milk ; 36 there, too, it varies 

 considerably, it is great in the milk from distillery fed 

 herds and less in milk delivered by the large companies. 



36 In 1895, the Copenhagen health commission had 39 samples of 

 milk tested for dirt, which was found in small quantity, varying be- 

 tween 1 and 13 milligrams per liter. 



