TMKKMAI. l'l;o|'Kl;TIKS OF CARBONIC ACID AT LOW TEMPERATURES. in:; 



Most, "t'tlifsc iiii'asiin'iiiriit^ an- new ; the details of what has IM-CII dime Ix-fure 

 (in p. 68 and in Part IV., p. '.!. 



In addition to the ordinary data given in #/> diagrams and tables, the authors have 

 given the values of I, so that a complete I<f> diagram might be constructed from the 

 data supplied in the paper. The authors have made this diagram, but before 

 publishing it they intend to make a series of throttling experiments on superheated 

 gas to check the constant-pressure curves, which have so far only Ixjen approximately 

 determined. 



P.S. Since this paper was completed the authors have commenced the gas- 

 throttling experiments referred to above. These may be used as an independent 

 check on the accuracy of the Q<f> diagram, ('housing an experiment as close to the 

 gas-limit curve as possible to avoid possible errors in the approximate constant- 

 pressure lines the confirmation obtained is remarkably good. 



Starting at the point " V," tig. 12, on the 700-lbs. pressure line, the gas was 

 throttled down to the 150-11)8. pressure line. The point reached is marked " W." 

 Calculated from the 6<j> diagram, the point W should have fallen exactly on the limit 

 curve;, />., at " E." If the limit curve be moved '0001 to the left, W and E will 

 coincide. A shift of '0001 corresponds to an error of '3 per cent, in the value of L. 

 This is the accumulated error in the whole set of measurements for the complete 

 cycle KAVWEGK shown in fig. 20. 



Fig. 20. 



The authors desire to express their special gratitude to Brasenose College for the 

 gift of the freezing machine with which the experiments were made. They also have 

 to thank Mr. D. H. NAGEL, of Trinity College, and Mr. H. B. HARTLEY, of Balliol 

 College, for advice on chemical questions and for having generously placed the College 

 Libraries at their disposal. 



