Knowledge of the Specific Volumes of Steam, 31 



determinations are worthless. Therefore those given above 



should have at least 2*5 per cent condensation ; hence, Battelli's 



pv 

 determinations being correct, -jp-bj Ramsay and Young should 



be, perhaps not 2*5 per cent smaller than by Battelli, for the 

 latter's volumes are smaller, but certainly 1*5 per cent smaller. 

 Instead of that the smallest of Ramsay and Young's is only 

 ■0*8 per cent smaller than the greatest of Battelli's, while one 

 of them is larger than any of the latter. We thus see that the 

 supposition that the deviations in 1 .... 8 are due to conden- 

 sation on the part of Ramsay and Young involves us in diffi- 

 culties. At any rate they show conclusively that in the region 

 considered either Ramsay and Young or Battelli is entirely in 

 error. 



Further, Ramsay and Young's experiments 11 .... 28 have 

 all the same weight of water with the exception of Nos. 20 and 

 22, and hence should have a practically constant deviation to 

 check with Battelli's. Nos. 11 .... 15 have such a constant 

 deviation of about 1*5 per cent, while Nos. 18, 19, 21, 

 23 . . ". . 26 have a fairly constant deviation of about 2 per 

 cent, different from the former. Hence we see that the two 

 investigations are entirely out of accord. One of them is in- 

 correct, perhaps both. 



We will therefore next examine Ramsay and Young's experi- 

 ments by themselves. First they discard all their experiments 

 below 75° C. as untrustworthy. At 75° their determinations 

 show consecutive variations as high as 1*6 per cent. Above 

 100° C. there was a great deal of condensation in every case as 

 the saturation line was approached ; this is shown by the rapid 

 increase of vapor density with increasing pressure. Thus at 

 140° C. total condensation occurred at a pressure of 2645 mm ; 

 the saturation pressure for that temperature is 2717. At 150°, 

 160°, 180°, 190° and 200° total condensation occurred at pres- 

 sures of 3442, 4571, 7444, 9337 and 11505 mm respectively ; the 

 corresponding saturation pressures are 3581, 4651, 7546, 9443 

 and 11689 mm . Aside from this the density showed an impossi- 

 bly rapid increase before condensation. 



There are some other discrepancies in Ramsay and Young's 

 observations which will merely be mentioned. Thus if com- 

 parison is made of those experiments at temperatures 270°, 

 260° and 250° for which the volumes are given as 0*644, 0*585, 



pv 

 0*529, and 0*435, it will be found that at constant volume 7=- 



decreases w T ith increasing temperature, which is impossible. 



The experiments below 250° at these same volumes, as well as 



pv 

 at others, make j=- at constant volume increasing with increas- 



