256 Professors Ayrton and Perry on 



too perfect a specialist, and so obtains no help from other 

 departments of physics than that in which he himself is 

 working. 



We have ourselves, for example, wasted much time in use- 

 less observation of what seemed to be capricious behaviour of 

 voltaic cells, a result to be expected when electricians who 

 are not practical chemists conduct chemical investigations. 

 Again, the specialist in pure mathematics might often do 

 much more valuable work if he had practised the application 

 of his mathematics to natural phenomena, for he would learn 

 of new directions in which to conduct his special investiga- 

 tions. We have been told by certain authorities in Chemistry 

 that a few chemists with a good working knowledge of 

 mathematics possess at the present time facilities for rapidly 

 improving our knowledge of chemical science. 



Drs. Ramsay and Young must forgive us for making their 

 recent papers the text of a discourse of this kind. We might 

 have selected papers by other authors which show more clearly 

 the truth of what we say ; but the work done by these two 

 gentlemen is of such a valuable kind, their scientific positions 

 are so well established, that we can venture to take this liberty 

 without feeling that we do any harm in making an illustration. 



These gentlemen read a paper at the last meeting of the 

 Physical Society, in which they gave the gist of two papers, 

 one of which had been published in the December number of 

 the Philosophical Magazine, and the other has since been 

 published in the January number. Members of the Society 

 will find the first of these in the number of the ' Proceedings ' 

 of our Society which reached them yesterday. Referring to 

 the papers in the Philosophical Magazine and to the published 

 abstract of the paper read before the Physical Society, we have 

 for saturated vapours : — 



I. Ramsay's first law : 



is constant for all substances at the same pressure ; 



,?1 52 L being latent heat, and s 2 and s 1 the specific 

 volumes of the liquid and saturated vapour. 



II. Ramsay's second law : 



at pressure p x bears a constant ratio to at 



s i~~ s z pressure^ for all substances. s i~~ s 2 



III. Young's law : 



t — is constant for all substances at any given pres- 

 sure ; t being the absolute temperature, and p the 

 pressure of a saturated vapour. 



