L62 Mr. M. M. P. Muir on Isomerism. 



Granted that there is an inner structure of the molecule, 

 we should, a priori, expect that changes in this structure 

 would he correlated with changes in the functions of the 

 molecule. And we must imagine that atomic motions are 

 continually taking place in the molecule ; hence under certain 

 conditions these motions may he directed so as to result in 

 the development of a form of energy different from that which 

 is developed when the atomic motions are otherwise directed. 

 If it he urged that the terms "molecule," "atomic motion," 

 &c. involve theoretical considerations, we grant the objection, 

 if objection it be. The same objection would apply to very 

 many of the most important dicta of science. Still it might 

 be said that by limiting our attention to the changes of function 

 (or of energy) we are dealing with facts, and with facts 

 alone. 



But if we speak of energy at all we must, I think, imagine 

 a something which is " the seat or vehicle of energy ;" to 

 this something we give the name of matter. Hence a change 

 of energy appears to involve in some way a change of matter. 

 If the body, the energy of which changes form, is not pos- 

 sessed of a molecular and atomic structure, but is continuous, 

 it must at any rate have a grained structure of some kind 

 (otherwise many well-established phenomena remain utterly 

 unaccounted for) ; and we can then imagine some kind c 

 change in the position of these grains. Such a theory of it - 

 finite divisibility of matter does not, however, explain so man 

 facts as the other (i. e. the molecular theory) does. We there- 

 fore prefer the molecular theory, and seek to associate with 

 changes in the energy of chemical substances changes also in 

 the structure of the matter composing these substances. 



3. Of course it is very possible to put a wrong meaning 

 upon the structural formulae which are used to express the facts 

 of isomerism. Three alcohols having the empirical formula 

 C 4 H 10 are known. These bodies do not undergo the same 

 reactions with the same reagents. In the formation of these 

 bodies " a fixed alteration has been produced in one or more 

 of their functions." Would it then be enough to inquire 

 " under what conditions of action " these alterations are pro- 

 duced ? Surely not ; we seek to determine w r hether there are 

 differences in the inner mechanism of those small parts of the 

 substances which remain united when the substances are hot. 

 And when we ' have, as it would appear, learned that there 

 are such differences, we of course seek to express these dif- 

 ferences in the formula) given to the substances. Thus to so- 

 called normal butylic alcohol is generally assigned the struc- 

 tural formula CH 2 (C 3 H 7 ) OH ; to secondary butvlic alcohol 



