204 



EEPOET 1886. 



NiTEOGEN — continued. 



Second Report of the Committee, consisting of Professor Tilden, 

 Professor W. Ramsay, and Dr. W. W. J. NicoL {Secretary), ap- 

 pointed for the purpose of investigating the subject of Vapour 

 Pressures and Refractive Indices of Salt Solutions. 



I. Vapour Pressures of Salt Solutions. 



Four salts, NaCl, KCl, NaNOg, and KNO3, have been completely examined, 

 in solutions varying in strength from one molecule of salt per 100 -water- 

 molecules up to solutions nearly saturated at the temperature of experi- 

 ment. 



The method employed was similar to that described in the previous 

 Report of the Committee, with this difference, that in this case the solu- 

 tions were kept of constant strength and the temperature -was the 

 variable. As before, the pressures at definite temperatures were deter- 

 mined, and not the converse. 



The experiments, though covering the same ground, are completely 

 distinct from those described in the previous Report, and are not only 

 more complete, but more reliable, being means of four independent 

 observations, and it is believed as free from the eflFect of superheating 

 as it is possible to obtain them by this method. The zinc introduced to 

 prevent succussive boiling has been proved to have no influence on the 

 results. 



The solutions were of the following: strengths : — 



all in 100 HjO, and the temperatures were 70°, 75°, 80°, 85°, 90°, 95°. 



