26 Starkweather — Regnault's Calorie and Our 



Paris) at 15° C, according to Rowland. This determination 

 has been strongly corroborated by recent experiments.* The 

 volumes follow : 



t 

 V 





 208*94 



10 



107-88 



20 

 58-505 



30 

 33-198 



40 

 19-637 



50 

 12-063 



60 



7-6703 



t 

 Y 



70 

 5*0320 



80 

 3-3942 



90 

 23464 



100 

 1-6587 



110 

 1-1973 



120 

 0-88099 



130 

 0-65948 



t 

 V 



140 

 0-50152 



150 

 0-38707 



160 

 0-30278 



170 

 0-23982 



180 

 0-19216 



190 

 0-15566 



200 

 012739 



Consider the possible errors in these. They may first have 

 an error of not exceeding one-half of one per cent due to the 

 determination of Regnault's calorie in kilogrammeters ; how- 

 ever much this may be, it is constant for all the Y's. Aside 

 from this there may be an additional error due to our uncer- 

 tainty as to the latent heats. This amounts to zfc 0*6 per cent 

 at 200°, is practically zero at 100°, and is ±0*5 per cent at 0°. 

 Below 40° the Y's are entirely uncertain owing to the errors 



dio 

 there in p and — already mentioned. 

 at 



In volumetric experiments on steam there is an unusual 

 amount of difficulty on account of condensation on the walls 

 of the vessel containing it. This condensation increases very 

 rapidly as the saturation line is approached, and as a conse- 

 quence all direct determinations of saturation volumes are far 

 less reliable than those calculated from the latent heats, for 

 Regnault so arranged his experiments that this source of error 

 was entirely avoided. An exception should be made of the 

 determination of the volume at 0° by Dieterici,f in which 

 more confidence can be placed, not only from the concordance 

 of his results, but also from the fact that corrections were 

 made for condensation. 



On superheated steam experiments have been made by Reg- 

 nault,;); Fairbairn and Tate,§ HirnJ Horstmann,T Herwig,** 

 Meyer,ff Battelli,^ and Ramsay and Young.§§ A large 

 number of observations prior to Regnault's are not included 

 here ; these are all at very low pressures, hence large volumes, 

 for which the substance can be treated as a perfect gas. 



* Johns Hopkins Univ. Circular No. 135, June, 1898, p. 54. 



f Wied. Ann., xxxviii, p. 1, 1889. 



X Mem. of the Inst, of France, vol. xxi, p. 100, 1847. 



§ Phil. Trans., clii, p. 591, 1862. 



I Theorie Mecanique de la Chaleur. 



"|[ Liebig's Annalen, Supplemental Band, vi, p. 51. 



** Pogg. Ann., cxxxvii, p. 592, 1869. 



ffChem. Berichte, 1877, p. 2068. 



XX Mem. R. Ace. Sc. Torino, (2). xliii, 1893. 



§§ Phil. Trans., clxxxiii A, p. 112, 1892. 



