38 Dr. J. A. Harker on 



Some Experiments on the Latent Heat of Steam. By 

 J. A. Harker, D.Sc, Berkeley Fellow in Physics in 

 the Owens College, Manchester. Communicated 

 by Dr. Schuster, F.R.S. 



(Received January 23rd, 1896.) 



In a communication made some time ago to the Literary 

 and Philosophical Society of Manchester (Memoirs and 

 Proceedings, Eighth Series, Vol. IV., pp. 37-53), Mr. 

 P. J. Hartog and the author described some preliminary 

 experiments on the latent heat of steam made with a 

 modified form of the apparatus designed for the purpose 

 by M. Berthelot (Mecanique Chimique, Vol. L, p. 288). 

 The original object of the work was more to test the 

 accuracy of the results given by a small apparatus of this 

 kind than a redetermination or even control of the work 

 of previous observers. 



A somewhat long series of experiments with variations 

 in many of the details — for example, the different means 

 of protecting from radiation the vertical tube down which 

 the steam passes to the calorimeter — led to the surprising 

 result that the value of L, the latent heat of condensation 

 of steam at ioo°, came nearly 2,\ per cent, lower than that 

 found by Regnault in his classic researches, an account of 

 which was published in the Memoires de l'Academie des 

 Sciences in 1847. 



On looking up the literature of the subject we found 

 that, except the experiments of Berthelot, which were 

 discussed in the paper alluded to, no results had been 

 published which could at all be regarded as a confirmation 



