78 MODERN METHODS OF TESTING MILK 



(Bull. 145, 1910, Purdue Agr. Exp. Sta.). As a result 

 of this work, the Official Dairy Instructors' Association 

 has adopted two forms of standard bottles for cream- 

 testing, (i) 50 per cent., Q-gram, so called 6-inch 

 bottle, and (2) 50 per cent., g-gram, so-called Q-inch 

 bottle, a detailed description of which is given on 

 page 276. 



These standard cream-bottles, have several advan- 

 tages, .as compared with the ordinary 1 8-gram bottles, 

 among which are the following : ( i ) Since the gradua- 

 tion extends to 50 per cent., richer cream can be tested. 

 (2) There is greater accuracy in reading the scale of 

 graduation, since it is possible to use a neck of smaller 

 diameter, thus increasing the distance between the 

 smallest divisions of the scale. (3) Decreased dia- 

 meter in the neck makes smaller the error introduced 

 by the meniscus, when this is not eliminated by special 

 treatment. (4) Direct reading of the percentage 

 avoids the error introduced by multiplying the read- 

 ing by 2, as when a Q-gram sample is tested in .an 18- 

 gram bottle. (5) The body, when large enough, per- 

 mits dilution of cream with water before adding the 

 full amount (17.5 cc.) of acid; this prevents charring 

 of fat. (6) Some cream is saved when the tests are 

 promptly made with each delivery in place of compo- 

 site tests, the annual saving being appreciable. 



CREAM-TESTING SCALES 



For weighing samples of cream, a set of accurate 

 scales is required. Different forms are illustrated in 

 Figs. 31, 3 1 a, 32 and 32a. Scales with agate bearings 

 are much preferable to other forms, since the agate 



