336 



THE BOOK OF CHEESE 



bottom. Each reading on the scale corresponds to the 

 point marked specific gravity on a hydrometer, except that 

 the figures are not complete. For example, 15 

 on the Quevenne scale means a specific gravity 

 of 1.015; a reading of 30 on the Quevenne 

 scale means a specific gravity of 1.030, and so 

 on. The Quevenne lactometer is graduated 

 to give correct results at a temperature of 

 60 F. The milk should be at this temper- 

 ature. If the temperature is below or above 

 this, a correction must be made to the read- 

 ing. The temperature should not be more 

 than 10 degrees above or below 60 F. The 

 correction for each degree in variation of tem- 

 perature can be made by adding 0.1 or sub- 

 tracting 0.1 from the lactometer reading, as 

 the case may be. If the temperature is above 

 60 F., the correction is added to the lactom- 

 eter and if it is below 60 F., the correction 

 is subtracted from the lactometer reading. 

 The reading should be taken when the lac- 

 tometer is floating free in the milk. The 

 scale is read exactly at the surface of the milk. 

 The better lactometers have a thermometer 

 with the scale just above or opposite the 

 lactometer scale. 



The Board of Health lactometer. This is 

 I Board~of verv s i m il ar to the Quevenne lactometer 

 Health lac- except that the scale is graduated from to 

 120 (Fig. 72). The point on the scale of the 

 lactometer that floats at the surface in water is represented 

 by 0, and 100 represents the specific gravity of 1.029. On 

 the Board of Health lactometer, the 100 degrees or divi- 



