162 Professor Thomas Preston [May 12, 



and that the differences which exist in the materials thus constituted 

 arises more from the manner of association of the ions in the atom 

 than from differences in the fundamental character of the ions which 

 build up the atoms ; or it may be, indeed, that all ions are funda- 

 mentally the same, and that differences in the value of e/m, or in the 

 character of the vibrations emitted by them, or in the spectral lines 

 produced by them, may really arise from the manner in which they 

 nre associated together in building up the atom. 



This may be an unjustified speculation, but there can be no doubt 

 as to the fascination which enquiry of this kind has always exerted, 

 and must continue to exert, over the human mind. It is the specula- 

 tion of the ignorant as well as of the philosophic and trained scientific 

 mind, and even though it should never be proved to rest on any sub- 

 stantial basis of fact, it will continue to cast its charm over every 

 investigator of nature. 



It is ever the desire of the human mind to see all the phenomena 

 of nature bound by one connecting chain, and the forging of this 

 chain can be realised only gradually and after great labour in the 

 laboratories of science. From time to time the hope has been enter- 

 tained that metals may be transmuted, and that one form may be 

 converted into another ; and although this hope has been more gene- 

 rally nurtured by avarice and by ignorance rather than by knowledge, 

 yet it is true that we never have had any sufficient reason for totally 

 abandoning that hope, and even though it may never be realised that 

 in practice we shall be able to convert one substance into another, 

 even though the philosopher's stone be for ever beyond our grasp, yet 

 when the recent developments of science, especially in the region of 

 spectrum analysis, are carefully considered, we have, I think, reason- 

 able hope that the time is fast approaching when intimate relations, 

 if not identities, will be seen to exist between forms of matter which 

 have heretofore been considered as quite distinct. Important spectro- 

 scopic information pointing in this same direction has been gleaned 

 through a long series of observations by Sir Norman Lockyer on the 

 spectra of the fixed stars, and on the different spectra yielded by the 

 same substance at different temperatures. These observations lend 

 some support to the idea, so long entertained merely as a speculation, 

 that all the various kinds of matter, all the various so-called chemical 

 elements, may be built up in some way of the same fundamental sub- 

 stance ; and it is probable that this protyle theory will, in one form 

 or another, continue to haunt the domains of scientific thought, and 

 remain a useful and important factor in our progress, for all time 

 to come. 



Even though it may be that a knowledge of the ultimate constitu- 

 tion of matter must for ever remain a sealed book to our enquiries, 

 yet, framed as we are, wo must for ever prosecute the extension of 

 our knowledge in every direction ; and in pursuing knowledge it 

 frequently happens that vast acquisitions are made through channels 

 which ill firsl seem most unlikely to lead us any further. It has 



