50 PRESIDENTIAL ADDRESS— SECTION P.. 



parenthetically, is the modest even-tempered genius of English 

 administration — the capacity to rectify her blunders at the 

 eleventh hour . . . even if she has to call an occasional Welsh- 

 man or Scotchman to the rescue ! 



It must therefore (irrespective of the parenthesis!) be 

 emphasised that the movement towards specialisation in chemistry 

 is only one side of the question of " broad outlines " and 

 " practical propositions." In the very process of specialisation 

 chemistry is widening its sphere of usefulness, throwing out 

 tentacles to grasp a whole range of subjects, which were for- 

 n-erly regarded as quite beyond the sphere of chemical handling, 

 and which even yet only the chemist recognises as belonging to 

 his proper province. It is true that it is rapidly becoming fashion- 

 able for every institution to have its " own chemist," but it is 

 not so sure that every institution knows what to do with him 

 v/hen it's got him. At the present moment administrative 

 departmental heads are in process of catching tartars — trouble- 

 some people who insist upon having a " different kind " of 

 breadth of outlook, and want to do things which look very un- 

 remunerative. 



To illustrate the way in which the highly specialised science 

 throws out its tentacles to the other sciences and broadens the 

 eutlook of civilisation, a few* concrete examples may be taken. 

 Going first to the subject of Astronomy, which to the non- 

 scientific mind would appear to be as untainted of chemistry as 

 could be desired, a connecting link is at once provided by phy- 

 s^'cal chemistry and its spectroscope, by means of which it is 

 possible to analyse substances which cannot be handled, but 

 from which light is available, and by means of which it is 

 possible to do such odd things a^ calculate the speed of a star. 



When a beam of complex light is passed through the prism 

 of a spectroscope the light waves are differentially diffracted, 

 so that each wave-length can be examined separately. The 

 range of the rainbow colours in the visible spectrum corresponds 

 to wave-lengths of one hundred-thousandth part of an inch 

 at the violet end. to three hundred-thousandths of an inch at 

 the red end, but since the range of wave-lengths capable of 

 aff'ecting silver salts is wider than that to which the human 

 eye is sensitive, it is possible to photograph the ultra-violet or 

 " invisible light," and so extend the range of spectroscopic 

 analysis. Spectroscopic examination of a substance may be 

 direct, by its so-called " emission spectrum." or indirect, by its 

 so-called " absorption spectrum," i.e., the spectrum obtained by 

 allowing light which produces a continuous spectrum to pass 

 through the substance to be examined before entering the spectro- 

 scope. In the former case a series of spectral bands, of colour 

 if the wave-lengths all fall within the range of the eye, is 

 obtained. In the latter a series of black " absorption bands," 

 characteristic of the substance, is produced. Each element, in 

 the condition of vapour, has its own characteristic spectrum. 



