DAVIS. — THE LAW OF CORRESPONDING STATES. 257 



of that run, and so on, no point being used more than once. The 41 

 values of the coefficient obtained in this way are summarized in Table 

 IV, and are plotted as small open circles in Figure 6. They lie in the 

 range between 0.8 and 0.9 reduced temperature, filling a gap of con- 

 siderable importance in that figure. 



The remaining 33 of the selected runs cannot be handled in the same 

 simple way, because the experiments which make up each of these runs 

 are not so related as to give throttling curves, but are related in an- 

 other way much better suited to the original purpose of the work, but 

 much less suited to the present purpose. Nevertheless the gap be- 

 tween 0.7 and 0.9 in Figure 6 is so important that it is desirable to 

 use every bit of information about it that can be obtained. These 33 

 additional runs have therefore been discussed at some length in the 

 appendix of this paper, and, suitable corrections for the high side tem- 

 peratures having been applied, the more favorable of them have been 

 used to get the 77 values of the Joule-Thomson coefficient which are 

 presented in Table IV. These values are plotted in Figure 6 as small 

 black dots. They are more self-consistent than the values in Table IV 

 above, but their trustworthiness is more uncertain as each involves two 

 uncertain corrections of the original data instead of one. They are 

 nevertheless valuable corroborative evidence. 



Figure 6 is now complete. The 82 values of the coefficient which are 

 summarized in Tables I., II., and III., lie in the range between 0.6 and 

 0.7 units of reduced temperature, and form a broad but reasonably well 

 defined band, within which there is no evident tendency for either of 

 the three sets of points to separate themselves from the others. The 

 118 values of the coefficient which were computed from Dodge's data, 

 and which are presented in Tables IV. and V., lie between 0.7 and 0.9 and 

 form a satisfactory continuation of the band. Above 0.9 are five large 

 circles with diagonal crossbars representing on the same scale the origi- 

 nal observations of Joule and Thomson on carbon dioxide, six large 

 circles without crossbars representing Kester's 7 experiments, and one 

 large circle with a horizontal crossbar representing Natanson's 8 result. 

 These circles form a surprisingly good continuation of the curve sug- 

 gested by the band of steam points. The law of corresponding states is 

 therefore verified for carbon dioxide and water within the limits of error 

 of the observations on the two substances. 



The various values in Tables I to V have been grouped according to 

 temperature and averaged. For this purpose a number was assigned 



7 Phys. Zeitsch., 1905, 6, 44; repeated and revised in Phys. Rev., 1905, 21, 

 260. 



8 Wied. Ann., 1887, 31, 502. 



VOL. XLV. — 17 



