98 Milk and Its Products 



these there are two forms. In one there is a bulb 

 in the middle of the neck, and graduations above 

 and below. Ordinarily the lower graduations have a 

 capacity of 5 per cent, the bulb a capacity of 10 

 per cent, and the upper graduations a capacity of 

 10 per cent. The use of this form of bottle re- 

 quires that when the fat is read off the bulb should 

 always be completely full, and the upper and lower 

 surfaces of the fat rest on the upper and lower 

 graduations respectively. Another form of cream 

 test bottle has a neck much wider than that used 

 for ordinary milk testing. Bottles of this form have 

 a capacity up to 35 per cent, or even more. The 

 graduations are usually not closer than .5 of 1 per 

 cent. This form does away with the awkwardness 

 of the bulb in the center, but it is not possible 

 to read the column of fat to so small a fraction, 

 usually to not less than .5 of 1 per cent. For 

 testing cream, particularly cream that is rich in fat, 

 a special pipette is necessary. The specific gravity 

 of cream containing 25 per cent of fat or over is 

 nearly that of water, 'and in testing cream of this 

 quality a pipette of 18 instead of 17.6 cubic cen- 

 timeters capacity is used. For testing skim -milk, 

 where it is desirable to read the small fractions of 

 1 per cent, two forms of bottles have been devised. 

 In one, two pipettes full of milk are used, and the 

 graduations have one -half the ordinary value ; in the 

 other form, the bottle has two necks, one of ordi- 

 nary width for the introduction of the milk and acid, 

 and the other an extremely narrow one, in which 



