46 



MODERN METHODS OF TESTING MILK 



color to the water or alcohol by adding some black 



aniline or carmine ink. Fill the bottle nearly to the 



zero mark and then finish with a pipette or dropper, 



•^ adding a drop at a time just 



to the mark. Any drops of 



liquid adhering to the inside 



walls of the neck must be re- 



o 



FIG. 19 



moved, using conveniently a 

 strip of blotting or filter pa- 

 per. The tester is then slowly 

 lowered into the neck of the 

 test-bottle until the liquid rises 

 half way between the two 

 sections of the instrument, 

 when the upper surface of 

 the liquid should be at the 5 

 per cent, mark (Fig 20), if 

 the scale is correct to this 

 point. If the surface of the 

 liquid is above or below the 

 fsi-'sl il\ 5 P^^ cent, mark, then the 

 scale is mcorrect to tliat ex- 

 tent. After the accuracy of 

 the 5 per cent, mark is tested, 

 the instrument is then lowered 

 into the bottle until the liquid 

 rises about one-eighth of an 



MILK-BOTTLE ACCURACY OF i„ch aboVC thc tOp of tllC Up- 

 TESTER MILK-COTTLE . . , ^- 



per section of the tester. It 

 the upper surface of the liquid is level with the 10 

 per cent, mark, the graduation is correct at that point. 

 The graduation of the scale is regarded as correct, if 



