i6o 



MILK AND DAIRY PRODUCTS PART 



B Si 



To do away with the necessity of calculating by interpolation, 



Wollny has constructed a special thermometer on which the 



highest allowable number 

 for a given temperature 

 can be read. 



In using this thermo- 

 meter, it is sufficient fco 

 remember that if the 

 refractometer scale 

 gives a higher reading 

 than the thermometer, 

 the sample is sus- 

 picious, otherwise it 

 may be regarded as 

 pure. It must also not 

 b'e forgotten that the 

 limits set by Wollny have 

 proved to be too low. 



On this thermometer 

 another scale ($) for use 

 with pigs' fat is also 

 etched. 



Another special ther- 

 mometer has been de- 

 signed to take into ac- 

 count the result of 

 Baiers' l investigations, 

 for pure butter fat during 

 summer feeding (June 

 to October) has different 

 limits from those of the 

 winter months (Novem- 

 ber to May). The dif- 

 ference between the 

 limits for summer and 

 winter butter is as much 



as two divisions, summer butter giving the higher number. 



Wollny's scale, which is older, lies about intermediate between 



the summer and winter scale. 



501 



FIG. 62. Wollny's 

 Special Thermo- 

 meter. 



FIG. 63. 

 Special 

 meter. 



Thermo- 



Zeitschrift. fur Untersuch. der Nahr.- und Genussmittel, 1902, p. 1,145. 



