Gil 



Issued May 31, 19LL 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY Circular No. 72. 



H. W, WILEY, Chief of Bureau. 



AN ELECTRICALLY CONTROLLED CONSTANT TEMPERATURE WATER 

 BATH FOR THE IMMERSION REFRACTOMETER. 



By H. C. GORE, Assistant Chemist, Division of Foods. 



The water bath of the immersion ref ractometer must be held within 

 narrow limits at 17.5 C. a temperature usually below that of the 

 room. It is therefore cooled by the addition of cold water. Admitting- 

 tap water or ice water at a constant rate is unsatisfactory, as constant 

 adjustment is required by changes in room temperature. The device 

 herein described, by which water is added to the bath automatically, 

 has given satisfaction during a period of many months. No claim to 

 originality can be made, in view of the many devices of this kind which 

 have been proposed. 



FIG. 1. Apparatus for temperature control of refractometer bath. 



The tap water runs through the sight tube A, figure 1, and is diverted 

 to the bath when the rubber tube B is closed by the lever of the 

 sounder C, In warm weather the water is cooled by passing it through 

 the copper coil D, immersed in ice water in the vessel E. The refrac- 

 tometer bath F is provided with an overflow pipe K and is stirred 

 by a current of air entering through a tube not shown; E and F are 

 insulated b} r magnesia packing to prevent the condensation of moisture 

 which occurs during warm humid weather. 

 93314 Cir. 7211 



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