CARE OF COMPOSITE SAMPLES 129 



ery operator is absent from the creamery, in order to prevent any 

 tampering with the composite samples. 



The best method of arranging the sample jars is to have all 

 the jars belonging to the patrons of each route standing in 

 one group, or on one shelf, if possible. The bottles are num- 

 bered to correspond with the number given each patron on the 

 milk sheet. The name of the hauler, or the number of the route 

 can be put on each shelf. The samples belonging to those who 

 haul their own milk can be put on another shelf; these can be 

 designated as individual haulers. Such a classification, when the 

 bottles are plainly numbered, will often prevent the mistakes that 

 are likely to occur if the bottles are simply numbered and put 

 into a rack together. 



Care of Composite Samples. In the first place, the jars 

 should be kept scrupulously clean. The tests are unreliable if 

 the jars are left covered with milk and molds round the neck 

 from one month to another. When the samples have been 

 tested the jars should be thoroughly cleaned, and, if necessary, 

 scalded, before they are used again. Care should be taken to 

 spill as little milk as possible around the neck, inside as well 

 as outside of the bottle, when the sample is put in. If the 

 milk is spilled there, it gives the bottle an unattractive appear- 

 ance. Very often it becomes moldy, and, as more milk is added 

 and the sample shaken every day, this mold gradually extends 

 down the sides of the bottle. This causes the composite sample 

 to be infested with undesirable growth, and to spoil sooner than 

 it would if greater care were taken in keeping the milk from 

 coming in contact with the sides of the bottle before coming 

 in contact with the preservative. 



A few drops but only a few of formaldehyde added to the 

 sample, where this is necessary, is a good preventive of mold; 

 but this should not be used as a substitute for thorough cleaning 

 of the bottles after each test period. 



It is important also that the sample jars be well covered; 

 otherwise the moisture evaporates, causing the milk or cream 

 to dry up, and, making the test unreliable by increasing the per 

 cent of butter-fat. A gentle rotary motion should be given each 



