QUANTITATIVE BACTERIAL ANALYSIS 25$ 



"bottle), etc., should be written opposite duplicate numbers in »• 

 "blank book or pocket card catalogue, or this information may be- 

 written on small tags and tied or wired to the corresponding test- 

 tube or bottle. 



Temperature. — The temperature should be taken immediately 

 after taking the sample for analysis, while the milk is still thor- 

 oughly mixed. 



If it is desired to take the temperature of " certified milk," 

 this should be done when the sample is taken, but from another 

 bottle. 



A floating thermometer, graduated to the Fahrenheit scale,, 

 is most convenient, and the temperature should be expressed to the 

 nearest degree. It is necessary to standardize the thermometer for 

 at least ten degrees on each side of the legal temperature limit. 

 A quickly registering thermometer should be left at least one min- 

 ute in the milk and read as soon as removed. A small piece of 

 clean absorbent cotton may be used to wipe the adhering milk from, 

 the thermometer that the scale may be easily seen. 



Representative Samples. — The collector should always select 

 his own sample, and care should be taken to secure a sample which 

 is truly representative of the milk to be examined. 



One of several methods of mixing the milk may be used, com- 

 parison having shown the results to be practically the same. 



1. Pouring the milk into a sterile receptacle and back. 



2. Shaking the milk thoroughly with receptacle turned up- 

 side down. (This may be done where the can or bottle is tightly 

 stoppered or capped and is not so full as to prevent thorough 

 agitation. ) 



3. In open tanks in stores it is allowable to stir thoroughly- 

 with the long-handled dipper generally found in use. 



4. Where the test tube collecting case is used, thoroughly re- 

 liable results are secured by first shaking the can or bottle; and,. 

 second, stirring with the large pipette before taking the sample,. 



