THE ANALYSIS OF MILK 25 



When the bottles have been read, turn them cork 

 upwards in the stand, remove the corks, and empty 

 the contents of the bottle into a convenient pot, not 

 down a sink. The pot when full may be emptied down 

 a well-flushed drain ; rinse the bottles two or three 

 times in hot water and leave to drain open end down- 

 wards ; an occasional clean with a brush when the 

 inside becomes dingy is necessary. The corks should 

 be put in a basin and washed several times with hot 

 water and allowed to dry. 



Care of the Machine. The bearings require lubrica- 

 tion ; an oil-can and a supply of suitable oil is provided 

 with the machine. If the ball-bearings wear loose, 

 they can be adjusted by means of a collar in the top 

 bearing. If a bottle breaks in the machine remove the 

 cup and wash it carefully, and should acid be spilt on 

 the disc, wash this too. 



The machine should be clamped and screwed to a 

 firm bench or table, preferably close to a leg. 



If separated milk is being examined a special bottle 

 with narrow neck should be used, and the time of 

 centrifuging increased. 



Cream cannot be tested direct, as the scale does not 

 go beyond 9 per cent., or in some bottles 6 or 7 per 

 cent., and a special bottle may be used. But cream 

 can be tested in the ordinary bottles by the following 

 method ; if a thin cream (containing less than 32 per 

 cent, fat) is to be examined, use a 3 c.c. pipette in place 

 of the ii c.c. pipette ; fill the bottle with acid as 

 before, and then add 8.2 c.c. of water from a pipette 

 graduated in -^ c.c. ; fill the 3 c.c. pipette with cream, 

 adjusting the upper level very accurately to the mark, 

 and wipe the outside of the stem ; hold the pipette 

 vertically over the centre of the opening and allow the 

 cream to run directly into the water and blow out the 

 last drops ; finally, add the amyl alcohol, and proceed 

 as described for milk. 



For thicker creams, a small balance weighing to 0.05 

 gramme (Fig. 18), and a pair or pairs of accurately 



