MILK TESTING 25 



shell cut one-half inch long will hold, loosely filled, 

 approximately one-half gram of bichromate. For 

 convenience in handling the shell can be soldered to a 

 piece of stout wire. Put the bichromate in the sam- 

 ple cans when empty, and no more need be added until 

 a new composite sample is started. The bichromate 

 imparts its characteristic yellow color to the milk. 



In case corrosive sublimate or any other poisonous 

 material is used for preserving the composite sample, 

 it is best to color the milk Avith aniline so as to pre- 

 vent accidental poisoning from use of the milk. 



Small four or six ounce, wide-mouthed bottles may 

 be used for holding the composite samples. Bottles 

 with glass stoppers are the best. Rubber stoppers 

 may be used, but cork stoppers should never be used. 

 They are difficult to clean, and they cause the milk to 

 sour. When the composite sample becomes " lumpy " 

 and is difficult to sample, a very small (.1 gm.) piece 

 of caustic potash may be added before mixing the milk. 

 The potash will dissolve the lumps of curd. A few 

 drops more than 17.6 cc. of acid should then be used. 



When only a small number of tests are to be made, 

 the following plan may be followed : Save about two 

 ounces of each milk separately in glass bottles or 

 cans ; at the next milking add a proportional quan- 

 tity. A composite sample of the day's milk is thus 

 obtained, and while still fresh is mixed, and then by 

 means of a small pipette, 5.9 cc. are measured into a 

 test bottle twice the size of those ordinarily used, or 

 test bottles made for 35 cc. of milk. In a similar 



