THERMAL PROPERTIES OF CARBONIC ACID AT LOW TEMPERATURES. 359 



pressure gauge read the gas pressure p it and the differential pressure gauge was in 

 equilibrium, which avoided any danger of blowing the mercury out of it. Just before 

 the end of each experiment the valve V 5 was closed and V 4 and V 6 opened and 

 readings taken on the differential gauge. 



The quantities measured in an experiment were : 



The rate of flow of the gas. 



Its initial pressure and the drop of pressure in the calorimeter. 

 The temperatures of the gas entering and leaving the calorimeter. 

 The electric power supplied to the calorimeter. 



-30 



30 



The following quantities were also noted : 



The temperature of the muff and of the atmosphere. 

 The galvanometer readings. 



The results are given in Table A (p. 376), arranged in the same way as in Table IV. 

 of the former paper. The correction for the small drops of pressiire in the calorimeter 

 is explained in Appendix VII. The results are plotted in fig. 4. 



