74 MODERN METHODS OF TESTING MILK 



volume of cream in each test-bottle is always made up 

 to about 17.5 cc. by adding water to the cream and 

 mixing before adding acid. 



SPECIAL CREAM-TESTING BOTTLES 



To test in one bottle an 1 8-gram sample of cream 

 containing over 10 per cent, of fat, the neck must be 

 made to hold more than the neck of a milk-bottle, that 

 is, more than 2 cc. This additional space must be ob- 

 tained (i) by using a neck of larger diameter, keeping 

 the length the same as in the milk-bottle or (2) by 

 making the neck longer, keeping the diameter the same, 

 or (3) by furnishing the neck with a bulb of definite 

 capacity. 



Different kinds of bottles. Cream testing bottles 

 differ mainly in the construction of the neck, but in 

 some cases the body of the bottle may vary in shape 

 and size. The neck varies in respect to shape, length, 

 capacity, diameter and fineness of graduation. The 

 principal varieties of cream-testing bottles on the mar- 

 ket are included under the following outlined descrip- 

 tion: (i) The neck is either straight throughout its 

 length or bulb-shaped in one portion. (2) The length 

 of bottle varies, being usually 6 or 9 inches, but spe- 

 . cial lengths of 6^ 'and 10 inches are made. (3) The 

 graduated scale measures 20, 25, 30, 40, 50 and 55 

 per cent., usually corresponding to a capacity varying 

 from 4 to ii cc. (4) The smallest divisions of the 

 scale vary from 0.2 to I per cent. (5) The gradua- 

 tion is directly based on the use of 18 grams of cream 

 in some cases and on 9 grams in others; the latter 

 form is desirable in creamery work. 



