82 Report of the Department of Bacteriology of the 



Table XVII. — Bacteria in Milk from Cows Cleaned by Hand or by Vacuum 



Cleaner. 



Grand average: Whole milk, 332; strippings, 139; difference, 193. 



of 23 germs per cc. in favor of machine cleaning and when the germs 

 in the strippings are deducted the balance is 30 per cc. in favor 

 of hand cleaning. 



These somewhat extended observations indicate that where the 

 vacuum is allowed to fall noticeably below 15 inches the results 

 from machine cleaning are less satisfactory than ordinary hand 

 cleaning. On the other hand when the vacuum in the cleaner is 

 held at approximately one-half an atmosphere, machine cleaning is 

 practically of the same efficiency as hand cleaning. Since the time 

 consumed by machine cleaning was almost twice that required for 

 cleaning by hand when the efficiency of the two processes was equal, 

 these data suggest that, in its present stage of development, the 



