32 MODERN DAIRY PRACTICE. 



9. Small wooden pieces, shavings, and pieces of fir- 

 leaves. 



10. Woollen threads. 



11. Linen threads. 



12. Soil-particles (rather frequent) and moss -particles. 



13. Fine threads (most likely cobwebs), etc. 



In these investigations I also found several impurities 

 in the milk whose presence I was unable to explain, as, e.g., 

 cheesy lumps, slimy substances with a firmer nucleus, shin- 

 ing, fat-like bodies, fine floss and grains, and similar 

 matters. As regards the liquid impurities appearing in 

 the milk, it need hardly be mentioned that they cannot be 

 detected by microscopic examination.* 



* The quantities of solid impurities in milk have been deter- 

 mined by Renk (MuncTiner Ned. Wochenschr., 1891, Nos. 6 and 7; Gen- 

 tralbl.f. Bact., 10, 193), Schulz (Arch. f. Hyg., 14, 260), Vogel (Ber. 

 Qes. Verb. v. Nurnberg, 1891, 78), Uhl (Zeitschr.f. Hygiene, 12, 475), 

 and Ostermayer (Inaug. Dissert. Univ. Halle, 1891). Renk examined 

 ninety samples of market milk and found the following average 

 quantities of impurities (mainly dung particles) in the milk of the 

 cities given. The fresh substance is calculated on basis of an 80-per- 

 cent water- content of the impurities : 



Leipsic. Munich. Berlin. Halle a. S. 



Dry substance, milligrams per liter 3.8 9.0 10.3 14.9 

 Fresh substance, " " " 19.0 45.0 51.3 74.6 



The maximum quantities of impurities were found in case of a 

 sample of Halle milk, containing 372.5 milligrams of fresh impuri- 

 ties per liter (nearly 6 grains per quart). 



Schulz determined the quantities of microscopic impurities in 

 Wurzburg milk, as sold in the city (I), as bought in the country (II), 

 and as milked into a glass jar (III) : 



i. n. ra. 



Dry substance, milligrams per liter 3.0 1.7 2.3 



Fresh substance, " " " 15.1 8.6 11.5 



The milk in case of I and II was strained through a fine gauze 



