CAKE OF MILK ON THE FAEM 



343 



8 



a 



b 1 



— C 



In some steam testers where the exhaust steam escapes into 

 the jacket and no ventilation is provided, the temperature of the 

 bottles will be too high. In such case, the bottles must be allowed 

 to cool to one hundred and thirty to one hundred and forty 

 degrees F. bj^ placing them in 

 water at that temperature for 

 several minutes before making 

 the reading. 



Imperfect tests. — If the f ore- 

 going directions have been 

 strictly followed, a perfect test 

 should result. It is not to be 

 expected, however, that the be- 

 ginner will always meet with 

 success. The next two para- 

 gra])hs may be helpful in find- 

 ing the trouble. 



An imperfect test is caused 

 by one of three things: (1) 

 Foam on the fat colunm ob- 

 scuring the upper meniscus; 

 (2) a dark-colored fat colunm 

 containing dark particles and 

 with dark i^articles obscuring 

 the lower meniscus ; (3) a light- 

 colored fat colunm containing 

 white, curdy material ol)scur- 

 ing the lower meniscus. 



The first is caused by using 

 hard water. Any one or a com- 

 bination of the following may 

 cause the second trouble : The 

 acid was too strong; too much 

 acid was used; the acid was 

 too warm when added to the 

 milk; the milk was too warm 

 when the acid was added; the 

 acid was dropped directly into 

 the milk; the mixing of the 

 acid and the milk was inter- 

 rupted before the solution was Fig. 174.— Method of reading Babcock 

 complete ; or the acid and milk test bottles, in reading fat column 



,, , . . T . , in milk testing, read from a to a, not 



were allowed to stand too long a to 6, nor d to c. 



d 



4 



