606 



BRIDGMAN. 



he could be sure that the reaction was complete, and on raising the 

 temperature he found the same lag also. The phenomenon is more 

 unusual with rising temperature. Upon the repetition of the experi- 

 ment, error from this effect was avoided only by very careful work, 

 profiting by the experience of the first run. It is necessary to run the 

 pressure several thousand kilograms beyond the equilibrium point 

 in order to be sure of the completion of the reaction. The completion 

 of the reaction is also greatly facilitated by running the pressure back 

 and forth several times over the transition before beginning the 

 measurements. In the neighborhood of the triple point II-III-IV, 

 where it is not possible to secure completion of the reaction by running 

 the pressure over a considerable range, because the pressure of equili- 

 brium is too near atmospheric pressure, the same end was attained by 

 raising or lowering the temperature, as occasion might require, and 

 then bringing it back to the temperature of the measurement. I had 



3456789 10 

 Pressure, kgfm./cm.^ x 10* 

 Ammonium Nitrate 



U 12 



Figure 13. Ammonium Nitrate. The observed equilibrium pressures 

 and temperatures. 



