[ 6*7 1 



the ingredients, the test bottles are corked and well shaken 

 before they are put on the rotary machine. The test bottles 

 are now submitted to centrifugal force in the machine for 

 2 or 3 minutes after which they may be taken out. 



1.126. The fat will be noticed to have collected on the 

 top of the liquid, that is, if the operations have been properly 

 performed, and it is generally of a palish yellow colour. To read 

 off the percentage, the fat must be brought on the graduated 

 scale on the neck of the bottle. This is done by pushing in the 

 India rubber cork. The bottom of the layer of fat is to be got 

 even with one of the long graduations, or where one sees one 

 of the numbers, and then it is a simple matter to read off the 

 percentage. Each space between the numbers represents one 

 per cent., which is sub-divided into 10 small divisions each 

 equal to T per cent. So that if we have three large divisions 

 and five small ones this would represent 3-5 per cent, of fat, 

 which is the composition of good milk. In reading, it is 

 necessary that the bottom of the fat should be exactly on 

 one of the large marks, and in reading off the decimal 

 percentage read up to the bottom of the meniscus, which is 

 always present at the top of the fat. 



1.127. The ash or mineral matter in the milk generally 

 settles at the bottom of the test bottle near the cork in the 

 form of a greyish white powder. 



1.128. The test bottle is to be cleaned out with hot 

 water immediately after use and if any fat is left in the 

 neck it should be removed with a fine brush or else it will 

 affect the accuracy of the next test. 



1.129. The test of butter in milk is no criterion by which 

 one could judge fraudulent adulteration. One sample of 

 milk may be so rich that it contains i\ per cent, of butter 

 and another may contain only \\ percent. It is very hard 

 tc say whether a sample of milk has been watered, or the cow 

 producing the milk has been fed injudiciously. Ordinary good 

 rnflk should give 9 to 10 per cent, of cream and about 3^ per 



