168 Testing Milk and Its Products. 



to butter. On the completion of the churning, the cards 

 are transferred to water of 175-190 Fahr., where they 

 are left for at least ten minutes to melt the butter and 

 "cook the butter milk into a curd." The oil will now 

 be seen mixed all through the mass. The test tubes are 

 then re-tempered to churning temperature and churned 

 again, by which process the curd is broken into fine 

 particles, which, when the butter is re- melted, will settle 

 to the bottom. The butter is melted after the second 

 churning by placing the tubes in water at 150-175 F., 

 allowing them to remain therein for at least twenty min- 

 utes. Some samples must be churned three or four times 

 before a good separation of oil is obtained. A clear 

 separation of oil is often facilitated by adding a little 

 sulfuric acid to the tubes. 



The length of the column of liquid butter fat is deter- 

 mined by means of a special rule for measuring the but- 

 ter oil; this rule shows the number of pounds and tenths 

 of a pound of butter which an inch of cream will make; 

 the first tenth of a pound on the rule is divided into five 

 equal parts, so that measurements may be made to two- 

 hundredths of a pound. The melted fat is measured with 

 the rule, by raising the tin card holding the bottles, to 

 about the height of the eye; the reading is recorded on 

 the driver's tablet under Test per inch, opposite the num- 

 ber of the particular patron. The test per inch multi- 

 plied by the inches and tenths of an inch of cream sup- 

 plied will give the butter yield in pounds, with which 

 the patron will be credited on the books of the creamery. 



204. The objection to this system of ascertaining the 

 quality of cream delivered by different patrons lies in 



