734 Reading-Course for Farmers' Wives. 



pail. Reduce the opening through which dirt can fall into the pail. 



An experiment was conducted to illustrate this point, and it was found 



that milk drawn in an ordinary milking pail contained 1,300 bacteria 



per cubic centimeter, while that drawn in a pail with opening about 



one-half as wide, contained only 320 bacteria per cubic centimeter. 



This is just what we would expect when we compute the number of 



square inches through which 



dust can fall into the different 



kinds of pails. For example, 



a pail having a top 14 inches 



in diameter has an opening 



of 153.86 square inches; a 

 Fig. 4=;. — Diagram shozvins size of openings -i -^i. • 1 , 1 



in various kinds of milk pails. The large Pail with I2-mch top has an 

 circle at the left represents the common milk opening of II3.04 square 

 pail. The others show the perpendicular . , r • 1 ^ 1 



exposure in the new kind of pails inches ; one of lO-mch top has 



an opening of 79.79 square 

 inches ; a pail with an opening of six inches in diameter has an exposure 

 of 28.26 square inches. Fig. 45. 



" Milkers should get into the habit of using the small-top pail as it is 

 one of the easiest of all ways for reducing the number of bacteria that 

 fall into milk. 



6. " Contamination by flics. — A fly or a bit of hay or straw or a piece 

 of saw-dust or a small hair, may carry enormous numbers of bacteria 

 into milk as is shown by the following experiments : 



"A living fly was introduced into 500 c.c. of sterile milk. The milk 

 was shaken one minute and it then contained 42 bacteria per c.c. After 

 24 'hours at room temperature, it contained 765,000 bacteria per c.c, and 

 after 26 hours 5,675,000. 



7. " Dirt in the milk. — A piece of hay about two inches long was placed 

 in 500 c.c. of sterile milk. The milk was shaken one minute and it then 

 conitained 3,025 bacteria per c.c. After 24 hours at room temperature 

 it contained 3,412,500 bacteria per c.c. 



" One piece of sawdust from the stable floor was put into 500 c.c. of 

 sterile milk. The milk was shaken one minute and its bacterial content 

 was then found to be 4,080 per c.c. After 24 hours at room temperature 

 it was 7,000,000 per c.c. 



"A hair from a cow's flank was put into 500 c.c. of sterile milk. After 

 shaking the milk for one minute it contained 52 bacteria per c.c. After 

 24 hours at room temperature it contained 55,000 per c.c, and after 36 

 hours, over 5,000,000 bacteria per c.c" 



