EXPERIMENT STATION WORK RELATING TO PURE MILK. 291 



were used in the experiments, one the ordinary open pail and the 

 other a pail provided with a closely-fitting cover, havin<^ on one side 

 a funnel 4 inches in diameter, across the bottom of which was a fine 

 wire gauze. Several layers of cheese cloth were held in place above 

 the wire gauze by means of a second funnel fitting loosely inside the 

 first. The whole apparatus was simple in structure and easily 

 cleaned. Determinations were made of the amount of insoluble dirt 

 in milk drawn into each of these pails. Fifteen tests showed on an 

 average 0.1103 gram of dried insoluble dirt in each liter of milk 

 drawn into the open pail, but only 0.0408 gram in each liter of milk 

 drawn into the covered pail, showing that 63 per cent of the dirt was 

 excluded by the cover. Straining milk removed only 46.6 per cent 

 of the dirt. The use of a covered pail is therefore shown to be 

 more efficient in the production of pure milk than straining milk 

 drawn into an open pail, especially as in the latter case a consid- 

 erable portion of the dirt is dissolved in the milk and can not be 

 removed by straining. 



An illustration of the value of observing aseptic precautions during 

 milking in improving milk, especially as regards its keeping qualities, 

 is afforded by experiments by Conn and Stocking." The milk of 

 one cow was drawn every other day in an ordinary open pail, and 

 no extra j^recautions were taken to exclude dirt or bacteria. On 

 the alternate days the milk was drawn under the following condi- 

 tions: The cow's tail was tied to the leg on the farther side; the 

 side, fiank, and udder of the cow were washed with a 3 per cent 

 solution of boric acid and wiped with a sterilized cloth; the milker 

 washed his hands with the boric-acid solution and wiped them with 

 a sterilized cloth ; after the milking was half done, the washing of 

 both the cow and the hands of the milker was repeated and the 

 remaining milk was drawn through four layers of sterilized cheese 

 cloth and a layer of absorbent cotton into a sterilized covered pail. 

 In two series of experiments the milk obtained under the extra pre- 

 cautions to prevent contamination contained 267 and 242 bacteria 

 per cubic centimeter as compared with averages of 3,888 and 3,116 

 respectively when no- extra precautions were taken. AVhen the two 

 kinds of milk were kept at 70° F., the milk obtained' in tlie ordinary 

 manner curdled on an average in seventy-nine hours, while the 

 cleaner milk did not curdle until the end of one hundred and thirteen 

 iiours. AVhen the samples were kept at 50°, the times of curdling were 

 respectively two hundred and twenty-six and four hundred hours. 

 At this temperature the average increase of bacteria in thirty-six 

 hours was thirty fold in ordinary milk, while in the milk obtained 

 under aseptic precautions the increase was only tenfold. The exjjcri- 



o Coimecticut Storrs Sta. Rpt. 1903, p. 52. 



