54 CREAMERY BUTTER MAKING 



weeks. The tablets color the milk so that there can be 

 no mistake about its unfitness for consumption. 



When colorless preservatives are used, like ordinary 

 formalin and corrosive sublimate, a little analine dye 

 should be added to prevent mistaking the identity of 

 milk treated with these preservatives. 



During the warm summer time the bichromate of 

 potash is not as satisfactory as either of the other two 

 preservatives mentioned, because of its comparative weak- 

 ness and liability to interfere with the test when too much 

 of it is used. When the bichromate is used in the ordi- 

 nary solid form not more than a piece the size of a pea 

 should be used, otherwise a good, clear test is not possible. 



For spring, fall, and winter use, however, bichromate of 

 potash is excelled by no other preservative, either in 

 cheapness, or safety and convenience in handling. 



Care of Composite Samples. It is a duty which the 

 butter maker owes his patrons to keep the sample jars 

 carefully locked up in the refrigerator when not in use 

 so as to prevent the possibility of anyone's tampering with 

 them. This will serve the additional purpose of excluding 

 the light and heat from the samples, for they will keep 

 but a short time when exposed to light and heat. 



When the sample jars are permitted to stand a few days 

 without shaking, the cream which rises will dry and 

 harden, especially that in contact with the sides of the 

 jar, so that it becomes difficult to secure a fair sample 

 on testing day without special treatment of the sample. 

 This is prevented by giving the jar a rotary motion every 

 time a sample of milk is added. 



It is important, too, that the covers of the jars fit tight, 

 otherwise evaporation takes place, resulting in an in- 

 creased test. In several instances the author has ob- 



