80 



Testing Milk and Its Products. 



cent., the graduation extending both below and above the bulb. 

 This is sometimes an inconvenience, as the water must be added 

 carefully so that the lower end of the column of fat will always 

 come below the bulb, in the graduated part of the neck, and 

 not in the bulb itself. Beginners are especially apt to lose tests 

 when this bottle is first used, for the reason given. It is rec- 

 ommended to fill these bottles with the first portion 

 of hot water to just above the bulb, so that one 

 can see how much water to add the second time in 

 order to bring the fat within the scale. 



Each division of the scale on these cream bottles 

 represents two-tenths of one per cent, of fat, as 

 in case of the milk test bottles. This form of bot- 

 tle is no longer used to any extent, as it has been 

 largely replaced by the Winton cream-bottle. 



91. Scales for weighing the cream. When 

 a small, delicate balance is used, cream can 

 be weighed rapidly into the bottles. Either 

 of the scales shown in the accompanying il- 

 lustrations, (figs. 34-35), will be found suf- 

 ficiently accurate for this purpose; a small 

 scale of this kind is also convenient and help- 

 ful in testing cheese, butter and condensed 

 milk, in determining the strength of sulfuric 

 acid, and in testing the accuracy cf test bot- 

 tles and pipettes. In testing cream by 

 FIG. 38. . 



The bulb- weight, the test bottle is first weighed empty, 



necked cream . , 



test bottle, and again when 9 or 18 grams 01 cream have 

 been placed in it; the difference between the two weights 

 gives the weight of cream taken for the test. If the 

 cream contains less than 30 per cent, of fat, the regu- 

 lar milk test bottle can be used for testing the cream, if 

 not much more than 5 grams are weighed out ; if more 

 cream is taken, or if this is richer than 30 per cent., it 

 is advisable to use cream bottles. 



