30 



BULLETIN 642, U. S. DEPARTMENT OF AGRICULTURE. 



Table 11. — Total number of bacteria found in clean-washed but unsterilized 



utensils. 



Series No. 



Washed can. 



Washed pail. 



Series' No. 



Washed can. 



Washed pail. 



1 



728,000,000 

 816, 000, 000 

 860, 000, 000 



5, 520, 000, 000 

 624,000,000 

 870, 000, 000 



1,580,000,000 



76,400 

 2,600 

 2,400 

 17,600 

 8,800 

 12, 600, 000 

 1,380,000 



8 



292,000,000 



1,220,000,000 



1, 180, 000, 000 



1, 6*0,000,000 



' i 16, 800, 000, OCO 



i 15, 600, 000, 000 



4, 200, 000 



652, 000 



2,200,000 



10,400 000 



2 



9... 



3 



4 



10 , 



i 11 



1 12 



13 



1 





1700,000,000 

 44, 000, 000 



6 



7 





, 



1 Held 8 hours before washing. 



During the work it was thought that one rinsing of a can with 

 sterile water probably did not remove all the bacteria from the in- 

 terior. To determine the point several tests were made, the results 

 of which are shown in Table 12. In the first test the can was rinsed 

 twice, with 400 cubic centimeters of sterile water each time. The 

 first rinsing showed 860,000,000 bacteria and the second 478,800,000, 

 or a total of 1,338,800,000 bacteria in the can. In a second test, in 

 which the can was rinsed three times, each rinsing showed large 

 numbers of bacteria, the count being lower after each rinsing. In a 

 third test, in which four rinsings were made, the last one still re- 

 moved a large number of bacteria. It follows from these results 

 that one rinsing removes only a portion of the bacteria from the can, 

 and therefore is not a true measure of the number of bacteria present. 

 The highest total count per o-gallon can in that test was 8,876,000,000 

 bacteria. A simple calculation proves that if this can were filled 

 with milk, 469,132 bacteria would be added to each cubic centimeter 

 through contamination from the can. This merely shows the possi- 

 bility of great contamination from unsterilized utensils. 



Table 12. — Effect of several rinsings in determining the number of bacteria 



in cans. 



Number of rinsing. 



Number of bac- 

 teria per 

 washed can. 



1 





860, 000, 000 

 478, 800, 000 



2 





1 



Total 







1.338,800,000 



5, 520, 000, 000 



2,640,000,000 



716, 000, 000 



2 





3 



I:::::::::::::::::::;::: 



1 



Total 



8,876,000,000 



624, 000, 000 

 316, 000, 000 

 109,000,000 

 72, 000, COO 



2 





3 . 





4 



• 





Total 



1,121,000,000 



