204 SCIENCE PROGRESS. 



From various considerations taking into account errors 

 incidental to certain methods and liability to constant errors 

 Morley gives the most probable value as i "42900 ±0*000034. 



In the same way experiments were made with hydrogen 

 and in live series but practically by three methods. 



First method was practically the same as the first series 

 of oxygen experiments. 



Second method was like the third oxygen series. 



Third method utilised the power of absorbing hydrogen 

 possessed by palladium. The hydrogen was weighed in 

 the palladium and expelled into globes, and its volume and 

 pressure determined at the temperature of melting ice. 

 Series III., IV. and V. were made by this method, but 

 the apparatus employed varied somewhat in the various 

 series. 



The values which result from these experiments are 



Series I. D h = -089938 gram. 



Series II. D h = '089970 gram. 



Series III. D h = -089886 + -0000049 gram. 



Series IV. D h = -089880 + -0000088 gram. 



Series V. D h = -089866 + -0000034 gram. 



The higher results of Series I. and II. are possibly due to 

 some constant error, probably traces of mercury vapour. 

 The most probable value is 



D h = -089873 + 0*0000027 gram. 



Part III. of the paper begins with a sketch of the methods 

 it was proposed to employ to determine the volumetric 

 composition of water. Of the three methods proposed Morley 

 unfortunately has only been able to carry out the one which 

 is the least satisfactory, viz., the determination of the 

 density of electrolytic gas and of the excess of hydrogen 

 over and above what the oxygen can unite with. Leduc 

 made a similar density determination, but apparently 

 assumed that the hydrogen and oxygen were in the exact 

 proportions in which they would recombine to form water. 

 Morley found that he always had an excess of hydrogen 

 when he kept his voltameter in ice and water, but that 

 when the temperature was allowed to rise to about 20° C. 

 then oxygen was in slight excess, so that no doubt at a 



