85 



Among other German strainers I mention the "Ditt- 

 mann's," which . consists of not less than 9 pieces, including 

 four metal strainers and two "cushions" of a sort of felting. 

 This has at least the merit of being- possible to clean, as it 

 can be taken to pieces. But as said before, prevention is bet- 

 ter than cure, and no amount of straining will purify milk 

 if pail after pail is poured on top of the dirt, and it may be- 

 come a detriment if the strainer is not kept perfectly clean. 

 A piece of flannel is easy to wash and when it felts too much 

 for reasonably quick straining, a new one may be had at a 

 small cost. 



FILTERING MILK. 



Among the systems of cleaning milk is the one used, I 

 belieA'e, first by the Copenhagen Milk Supply Co. They had 

 an apparatus where the milk entered at the bottom and 

 passed through a deep layer of sponges laid between perfor- 

 ated plates. The keeping of the sponges clean proved a ter- 

 rible task and later layers of gravel were substituted. 



A gravel filter designed by Scheller and Schreiber, of Ger- 

 many, is shown in Fig. 81. The milk enters at e through 



a strainer, passes through 

 the coarse gravel d, and 

 then by the pipe f, through 

 the perforated double bot- 

 tom b in the lower compart- 

 ment; through the fine gravel 

 n to the outlet g. The ap- 

 paratus is drained by the 

 valve at h. Dr. H. Tiemann 

 reports in Milch Zeitung 

 some experiments with this 

 filter, showing that 60 per 

 cent of the original slime 

 and dirt was removed, and 

 that the number of germs in 

 the unfiltered milk varied 

 from 49 to 166 millions in 

 one c. c., and in the filtered 

 milk from 46 to 168 millions, 



showing but a small improvement from a bacteriological 

 standpoint. The capacity of No. 00 is fully 600 Ibs. per hour. 



Fig. 81. 



