H 



NEW METHOD FOR DETERMINING COMPRESSIBILITY 



Data for Compressibility of Bromine. (2oC., Hydrogen Scale.) 



As will be observed, the pressures of the starting points of these 

 five series vary considerably. In order to bring them to comparable 

 conditions, we resorted to the following method : The first series, 

 that with the lowest starting point, was plotted with " total percentage 

 changes of volume of bromine minus those of mercury" in the direc- 

 tion of ordinates and the pressures corresponding to these volume 

 changes as abscissas. The portion of the curve below 46 atmospheres 

 was extrapolated. Let us call this curve one. To plot the results 

 of series 2, for example, we found the point on curve one, which 

 corresponded to the initial pressure (68) of (2) ; and its ordi- 

 nate gives the amount a 2 which must be added to the ordinates 

 calculated for higher pressures before the loci of series 2 could be 

 plotted. 



In other words a is the volume, constant within each series, 

 which must be added to each member of the series in order to reduce 

 them all to the same origin. It is found exactly as in the case of 

 mercury already discussed, being the ordinate corresponding to the 

 initial pressure of each series, measured on the curve of Series I. By 

 adding this quantity a n , all the series are superposed at their lowest 

 pressures, and the resulting curve begins at the origin of pressure and 



