222 FARM AND SCHOOL PROBLEMS. 



18. In turning crank of machine, give it the speed according to 

 directions (usually 75 turns per minute). . 



Summary. 

 Following are the various steps necessary in testing milk: 



1. Secure a representative sample. 



2. Measure out the required amount of milk with the 17.6 c. c. 

 pipette and deliver it to the test bottle. 



3. Add 17.5 c. c. sulpihuric acid for whole-milk, 20 c. c. for skim- 

 milk; mix gently, but thoroughly. 



4. Place in centrifuge and whirl at full speed for 5 or 6 minutes 

 for whole-milk, 7 or 8 minutes for skim milk. 



5. Add hot water to bring the fat up to the neck of the bottle. 



6. Whirl again at full speed for 2 or 3 minutes for whole-milk, 

 3 or 4 minutes for skim milk. 



7. Add hot water again to bring the fat up in the neck of the bottle 

 to the 8 or 9 percent mark. 



8. Give final whirling at full speed for at least one minute. 



9. Read the test at 185 to 140 degrees Faihr. 



10. Record the test and empty the 'bottles immediately; cleanse 

 thoroughly by shaking to remove sediment. 



Dairy Herd Records. 



From 1899 to 1908 (inclusive) The U. S. Dept. of Agri- 

 culture canvassed 13 states (la., Wis., Ind., O., N. Y., Penn., 

 Ct, Vt, Minn., Mich., N. H., Mass., and 111.) and reported the 

 records of 2,163 herds, containing 28,447 cows. 



The herds examined were representative herds, showing 

 fairly the equipment and practice prevailing in the territory 

 covered. 



The results showed that : 



1 . The yearly cost of feed per cow was $33.43. 



2. The number of pounds of milk per cow 



yearly was 4,213 Ibs. 



3. The pounds of butter yearly per cow was 196 Ibs. 



4. The pounds of butter fat yearly per cow 



was 158.4 



5.- The price received per 100 pounds of milk 



was 1 , 036 



6. The price of butter per pound was 0.186 



7. The price of butter fat per pound was 0.249 



