88 MODERN METHODS OF TESTING MILK 



ances the weight. In case too much cream is run 

 into the bottle, the surplus can easily be withdrawn 

 by the pipette. No cream must be allowed to get on 

 the outside of the bottle or on the scale-pan while the 

 weighing is done. 



Using less than 18 grams. As we have already no- 

 ticed, special bottles are made which have the gradua- 

 ted scale based upon the use of 9-gram samples, and 

 the results are then read directly from the neck with- 

 out any kind of correction. When, however, we use 

 9-grams of cream in a bottle made for an i8-gram 

 charge, as may be done in case of very rich cream, 

 the reading of the fat-column is multiplied by 2 ; any 

 error in the test is, therefore, doubled in the final re- 

 sult. A somewhat inconvenient method, which is little 

 used, is to weigh an 1 8-gram sample and divide it be- 

 tween two cream bottles, in which case water is added 

 to each bottle in amounts sufficient to bring the mixture 

 to about 18 cc. in volume. The results of the test in 

 the two bottles are added. 



It will be found more convenient with a little prac- 

 tice to weigh exactly 9 or 18 grams than to run in an 

 approximate amount and weigh that accurately. 



In case one uses in 1 8-gram bottles any amount less 

 than 1 8 grams for a sample, it is necessary to correct 

 as follows the per cent, of fat read: Divide 18 by the 

 number of grams of cream used and multiply the result 

 by the per cent, of fat read in the test. For example, 

 one uses 13.5 grams of cream and the result reads 15.^ 

 per cent, of fat. Divide 18 by 13.5 which gives 1.33, 

 and multiply this by 15.6, which equals 20.8 per cent., 

 the true percentage of fat in the sample. 



