28 Starkweather — RegnauWs Calorie and Our 



Similarly the numbers should increase in each of the follow- 

 ing columns : 



3-347 



3-341 



3-350 



3-361 



3-382 



3-350 



3-382 



3-362 



3-392 



3-286 



3-355 



3-345 



3-362 



3-361 



3-337 





There are a few other discrepancies, but these involve one-half 

 of his experiments, and it is difficult to get any concordance by 

 throwing out a few of the experiments. That there was a 

 tendency towards condensation is shown by the fact that in 



four of his experiments the value of— is less than is given by 



the saturation line for the same pressure, the difference being 

 more than can be allowed by any error in the latter. 



Suppose we ascribe these discrepancies to condensation, 

 throwing out accordingly about nine experiments. The 

 remainder are so few that they are only useful as a corrobora- 

 tion of others. Three of them are comparable with both 

 Horstmann and Battelli and deviate from Horstmann about 

 one per cent, from Battelli about one-half per cent, and this is 

 in a region where the deviation from a perfect gas is only 

 about 2£ per cent. Five others are comparable with Battelli. 

 Of these two are in agreement, one deviates about % per cent, 

 and the other two deviate 2 per cent. In the last two the total 

 deviation from a perfect gas is about 6 per cent. 



Of Horstmann's four experiments one is shown to be incor- 

 rect by a comparison with the others. The remaining three 

 agree fairly well with Battelli. 



Herwig himself discards fifty-five of his seventy-five experi- 

 ments as showing condensation due to too near an approach to 

 the saturation line. Of the remaining twenty, fourteen are in 

 a region where the substance should behave sensibly as a per- 

 fect gas. Of the other six, five are comparable with Battelli. 

 Two are in agreement, while the other three give deviations of 

 0-6 per cent, 1 per cent, and 2*5 per cent. 



We thus see as general conclusions from the foregoing that 

 among the experiments of Begnault, Fairbairn and Tate, Hirn, 

 Horstmann, Herwig and Meyer, we have available thirteen by 

 Hirn, three by Horstmann, and six by Herwig. So many of 

 Hirn's and Herwig's had to be thrown out as to render the 

 others doubtful, but even accepting them we have found that 

 in the only comparisons which can be made, those of Horst- 

 mann and Hirn, there is some disagreement, and the experi- 

 ments are not sufficiently numerous to give an accurate idea of 

 the deviation of steam from a perfect gas in various regions. 

 Nor are they useful as corroboration of Battelli's experiments, 



