142 EXPERIMENT STATION. [Jan. 



HEADING THE BABCOCK TEST, 



BY P. H. SMITH. 



Introduction. 



During the summer of 1909 an investigation was undertaken 

 to determine the best method of reading the column of fat in 

 the manipulation of the Babcock test. 



Babcock ^ in his first description of the test advocates reading 

 "the divisions which mark the highest and lowest limits of the 

 fat," which would, of course, include the upper and lower 

 meniscus. Subsequent experiments proved that such a practice 

 gave too high results, especially for cream tests in cases where 30 

 and 50 per cent. 6-inch Connecticut cream bottles were used, 

 and the method of reading to the bottom of the upper meniscus 

 became quite prevalent in certain sections of the country. This 

 station has held, however, that until recognized authorities ad- 

 vocated this method, it was better to hold to the original method, 

 in order that results of different chemists and creamery men 

 might be comparative. It was not, therefore, until 1908, when 

 a widely used text-book - recommended omitting the upper 

 meniscus from the reading, that it was considered by the ]\Ias- 

 sachusetts experiment station. 



An objection to reading tests to the bottom of the upper menis- 

 cus is founded upon the fact that the depth of the meniscus, is in- 

 fluenced by several factors, including diameter of the neck of the 

 bottle, color and clearness of the fat column and different light 

 effects. Different persons conscientiously attempting to read 

 the same test correctly may vary considerably in their results. 

 In order to eliminate this error Eckles ^ recommends the use of 



* Bulletin 24, Wisconsin Agricultural Experiment Station. 

 ' Testing; Milk and its Products, Farrington and Woll. 

 ' Chicago Dairy Produce, July, 1908. 



