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PURE CULTURES FROM PATHOLOGIC MATERIAL 



therefore, from time to time, be inspected. The sense of smell and a 

 lighted candle applied carefully along the tube will detect any leakage. 

 The thermoregulators used in connection with thermostats with 

 gas as a source of heat are generally constructed and based on the 

 following principle : The gas is led into the upper part of the thermo- 

 regulator through a good dense hose, connected with an upper tube 

 of the instrument, which is ground into the lower part. The vertical 

 limb of the T-shaped upper part of the thermoregulator is drawn 



FIG. 80 



FIG. 



Incubator thermometer. 



Thermoregulator. 



out conically and has an open tip and a number of small pinhole 

 side openings. The lower, longer tube into which the T-tube fits is 

 filled with mercury and the height of the column of mercury can be 

 regulated by a screw working in a lateral branch of the lower sealed 

 glass tube or mercury receptacle. If the column of mercury closes 

 the lower opening of the T-tube then gas can escape into the lower 

 tube only through the pinhole openings of the T-tube. The lower 

 glass tube or receptacle for the mercury has, well above the level of 

 the liquid, a lateral tube which is connected with the micro-gas lamp 

 by a rubber hose. If the mercury shuts up the lower end of the 

 T-tube very little gas can get to the lamp, and it burns with a small 

 flame. If the mercury recedes from the lower end of the T-tube, 

 gas can readily entei the lower glass tube and the gas lamp receives 

 an abundant supply and burns with a large flame, giving much heat. 

 Starting of the Incubator. The incubator is started in the following 



manner : 



