162 MASS. EXPERIMENT STATION BULLETIN 187. 



The author states: "After all the milk had been passed through, the 

 machine was taken apart and the amount of slime deposited on the walls 

 was carefully removed, placed in a bottle, and weighed." He does not 

 say whether it is moist weight or dry weight. 



It is apropos that the extensive work of Lieutenant Davies^ be in- 

 serted here, inasmuch as it contributes very suggestive data. The authors 

 present it exactly as it was found. The results secured furnish informa- 

 tion upon slime-yield nowhere else to be found, and it has these advantages: 

 The amount of slime is measured from milk of individual cows, and where 

 it has been possible to point out abnormaUties this has been done. In the 

 interpretation of Lieutenant Da vies' results it will be well to keep in mind 

 that very small amounts of milk were used, which usually leads to a high 

 percentage of moisture in the slime; that the weight is moist weight which 

 is subject to great fluctuation; and that the diagnosis of abnormaUties 

 appears crude because no intimate study has been made. Yet these data 

 are far more suggestive of what is involved in the process of clarification, 

 so far as sUme production is concerned, than can be gleaned from almost 

 any other source. 



Clarification of Certified Milk (Da vies). 

 Methods. 



De Laval Clarifier No. 95 was used in this work, its capacity being well 

 suited for the work, the quantities of mUk from each cow being very variable 

 and usually small. In place of the tank suppUed with the clarifier a funnel 

 was fitted so that given quantities could be easily measured. At the same 

 time there was the advantage that every bit of milk could be passed through 

 the bowl without rinsing with water; also no particles of dirt could remain on 

 the side. While the latter was of no consequence with the certified milk, it 

 does make a difference with the ordinary market milk. 



Three bowls were used; this allowed plenty of time for washing and steriliz- 

 ing them. The bowl shell was weighed while quite dry before the test. The 

 milk was clarified immediately after being drawn, 4 quarts being used where 

 possible; if less than 4 quarts, then all the milk was clarified. The bowl was 

 allowed to run down itself, any attempt to stop it quickly seemed to shake 

 the sUme film off on to the discs, and weighing was impossible. The bowl was 

 wiped dry and weighed; the amount of slime was calculated in per cent, of 

 milk clarified. 



The cows were tested as often as circumstances would allow. No attempt 

 was made to keep any definite order, it being found best to test whenever the 



1 Lieut. E. L. Davies was connected with this department as a graduate assistant at the time 

 this work was done. It was, however, executed independently of this bulletin and as a minor 

 thesis. He was majoring in microbiology and pursuing dairying as one of his minors in his 

 graduate work. He became restless when the war opened and tried many times to enter the 

 Canadian service, but was refused on account of physical disability. He was invited by Prof. 

 Dan H. Jones of the Ontario Agricultural College to become a member of the bacteriological staff. 

 Remaining there for a period, and removing his physical disability at the same time, he again 

 became restless for active service. He was accepted into the officers' school. After several 

 months of training on this side, together with local service, he was sent to France. He experienced 

 active service in the trenches at once. Within six weeks he was shot down by Germans whom he 

 was making prisoners. 



