DAIRY FARMING DAIRYING. 281 



fat in skim milk, for 4.000 lbs., 0.009. and for 4,500 lbs., 0.071. The influence 

 of tbe speed of the separator on the skimming is shown by the findinLC of 0.064, 

 0.067. and 0.074 per cent of fat in the skim milk, respectively, when the separa- 

 tors were run at 10 per cent above normal speed, normal speed, and 20 per cent 

 below normal, this being the average for all. three se]iarators and skimming 

 temperatures. 



When the position of the cream screw remained the same, changes in the 

 skimming temperature and the fat content of the milk caused but little varia- 

 tion in the percentage of cream obtained, but changes in the speed and the 

 amount of milk seitarated caused considerable variation, increasing with larger 

 amounts of milk separated or with lower speed. Sejiarator C was most sensi- 

 tive to these changes, and B least sensitive. The changes to which the per- 

 centage of cream is subject on account of changed speed or amount of milk 

 separated tend to counteract the changes in the skimming efficiency which 

 would otherwise appear, and they can sometimes wholly counteract these so 

 that it may appear as if an increased speed or a smaller amount of milk sepa- 

 rated gives a poorer skimming, and vice versa. 



Trials on the influence of the fat content of the milk on the skimming showed 

 that under otlierwise similar conditions more fat will remain in the skim milk 

 from rich milk than fi-om ]ioor milk, but not proiiortionately more, and that 

 rich milk is therefore skinuned relatively better than milk low in fat. 



The yield of butter obtained did not increase in quite the same proportion as 

 the closeness of skimming, so tliat there appears to be a limit beyond which it 

 is useless to carry the clean skimming if cleaner churning is not obtained at 

 the same time. The trials made, however, show that tliis limit has not yet 

 been reached, and it is tlierefore important in practical creamery work to skim 

 as clean as possible. 



In order to determine whether tlie separators under investigation worked 

 satisfactorily as compared with those found in most Danish creameries, analy- 

 ses of skim milk from the daily run in 426 creameries were made, and these 

 ranged between 0.030 and 0.310 per cent, averaging 0.094. The difference be- 

 tween this percentage and the average for the three separators (0.070) repre- 

 sents about 1,000 lbs. of butter annually for an aA-erage sized Danish creamery. 



Cream separators deliver the m.ilk mixed with more or less foam. Separator 

 A gave 45 per cent of foam, B 40, and C 37, on the average for all skimming 

 temperatures. The higher the temperature the more foam, and at .35°, 55°, 

 and 75° C, 35, 40. and 46 per cent of foam, respectively, was found in the skim 

 milk; at increased, normal, and decreased speeds, 44, 42, and 3S per cent of 

 foam, respect ivel.v, was obtained. 



During the skimming, slime collected in the separators, but under normal 

 conditions all three makes finished a whole rnn without its being necessary to 

 clean them, and it was found that the slime did not affect the closeness of the 

 skinuuing. Even when the bowls were so filled with slime that tlie percentage 

 of cream was increased to about three times noi'mal, the percentage of fat in 

 the skim milk was not increased above normal in the case of any of the 

 separators. 



The power required for running the three separators was 2.3S. 1.34. and 1.30 

 H. P. for A. B. and C. respectively, at normal speed and capacity, but as 

 creameries can utilize fully all waste steam during the time the separators 

 are running the loss of heat on account of a high power requirement of a 

 separator can therefore only be estimated at about * lb. of coal per H. P. hour. 



All the separators ran smoothly, and there was no appreciable wear on their 

 bearings after 20 months' service. For sejiarator A tbe inertia with respwt to 

 the peri^endiculur axis was 12 per cent larger than that with regard to an axis 



