176 THE FREEZING POINT OJ?" MILK. 



The following is a description of the method andf 

 apparatus that have been used in the Government Chemical 

 Laboratory, Brisbane, for the last three years. The^ 

 diagrammatic sketch shows the arrangement of the very 

 simple apparatus required. 



"A.'* is a stand made of wood 1 cm. thick, 30 cm. 

 high, 31 cm. wide and 18 cm. deep. Two rests " B "^ 

 at a height of 9 cm. carry a movable shelf " C." on which 

 the vessel containing the freezing mixture stands. We 

 use a porcelain beaker " D '' 16 cm. high by 10 cm. wide 

 for a freezing vessel, and tie around it for insulation, a roll 

 of flannel to the thickness of about one inch. 



A circular hole '' E." centrally situated in the top of 

 the stand carries the milk tube " F." We use a flat bottomed 

 tube 14 cm. deep and 3 cm. diameter for holding the milk 

 sample. We find it much easier to get agreeing results 

 with this size of tube than with the longer round bottomed 

 tube recommended by Winter. 



The indiarubber cork has two perforations for carry- 

 ing thermometer and stirring rod respectively. 



The first thermometer we used was a Beckmann 

 graduated in i,\„ths. The special thermometer devised 

 by Winter for this work was subsequently obtained from 

 Paris, but we found the Beckmann easier to read. For 

 the last year, a thermometer graduated in ^i^ths, a 

 degree covering 8*5 cm. of the stem, and specially made 

 for us of normal glass by the V.F.L. has been used and give» 

 splendid results. The trouble of having to occasionally 

 readjust the mercury of the Beckmann has been avoided, 

 while the true zero point which is determined afresh, at 

 least once every day on which the thermometer is used, 

 has not varied more than 0*02° C. A small telescope "H'' 

 is used for reading the thermometer. The telescope is 

 mounted on the stand in the usual manner. The 

 stirrer "K." is a brass I'od 2 m.m. in diameter, the spiral part 

 being partly flattened out and armed with four small points 

 of wire to break up the ice formed in standardising. 



In practice, 50 ccs. of each milk to be tested is put into 

 a tube, fitted with a cork, and the tubes are put into crushed 

 ice niul allowed to remain there (generally standing in the 



