SPECIFIC HEAT OF AMMONIA. 



335 



mometer in a steam hypsometer, a bridge reading may be 

 made with the hnk in the 25 ohm position, and then by 

 shifting the Hnk to the 34 ohm position and moving the plug 

 in the one ohm bank back 9 steps, and again balancing with 

 the shde wire, a second reading is obtained which is equal 

 to the first, which gives an equation determining the 



5PECIAL CALORIMETER BRIDGE 



LOSfl 



observing > 

 tme;rmome.ter< 



Figure 5 



unknown value of the nominally 9 ohm coil. The bridge 

 is designed for use with thermometers having a resistance 

 at 0° C. of 25.3 ohms and a fundamental interval of about 

 10.0 ohms. By double settings at the steam point (100°), 

 the napthalene point (218°), the benzophenone point (306°), 

 and the sulphur point (445.7°), the four extension coils may 

 be accurately determined. A thermometer may be cali- 

 brated and the extension coils measured at the same time. 

 The measuring current used with this bridge was about 

 0.004 amperes. 



