168 



MILK 



neck or the neck is made longer than the neck of a milk bottle, or, 

 again, the diameter of the neck may be enlarged. 



The earliest cream-testing bottle had a neck too long to fit in 

 the majority of centrifuges. For this reason the type with a bulb 

 was designed. The bulb type requires care when the water is 

 added, otherwise the bottom or top of the fat column may be lo- 

 cated in the bulb which has no graduations. The percentage of fat 



can be read in this style of bottle 

 only when the top and bottom of 

 the fat column falls in the gradu- 

 ated part of the neck. The Winton 

 cream-testing bottle has a wide neck 

 without a bulb and is graduated to 

 measure 30 per cent, cream. By 

 using a 9-gram charge instead of 

 18, cream up to 60 per cent, fat 

 content can be tested in this bottle. 

 When a 9-gram charge is used the 

 result must be doubled. The grad- 

 uation records 0.5 per cent., but 

 even 0.25 per cent, can be read with 

 accuracy. 



Cream-testing bottles which are 

 graduated to read the percentage of 

 fat directly when a 9-gram charge 

 is used are also obtainable. 



The smaller the diameter of a 

 cream-testing bottle, the greater is 

 the distance between divisions and 

 the more accurate is the reading. 

 Webster's experiments seem to show 

 that 30 per cent. 9-inch bottles 

 graduated to 0.2 per cent, are the 

 most accurate. The results must 

 be doubled when these bottles are 



Fig. 63. Cream testing bot- 

 tles. The surface of the fat col- 

 umn is curved from A to B as 

 shown in bottle No. 1, with the 

 medium point C not clearly de- 

 fined, while in bottle No. 2 the 

 top of the fat column is made 

 clear at C by the fat-saturated 

 alcohol D. (Bull. No. 195, 1910, 

 Univ. of Wis. Agri. Exp. Station.) 



used. The 50 per cent. 9-inch bottles graduated to 0.5 per 

 cent, are next in accuracy. Bottles with 6-inch necks are not 

 accurate. 



The Official Dairy Instructor's Association has recognized two 

 types of cream-testing bottles, namely: 1, a bottle with a 6-inch 

 neck, and 2, a bottle with a 9-inch neck. Both styles are gradu- 

 ated to 50 per cent, and are calculated on a 9-gram charge. 



The standards for construction and graduation of Babcock 

 glassware adopted by the Association of Official Agricultural 

 Chemists in 1908 are these: 



