884 



attraction,, just as this is the case with electric currents in the 

 same direction. But when ojie of the atoms is replaced by one 

 of another nature, e.g-. of greater atomic weight, the size of the 

 alom that has not been replaced, changes, because a stronger current 

 acls on it, i.e. this atom becomes smaller, whereas the second atom 

 becomes larger tlian it woidd bo if it had continued to be united 

 with one of its own nature, and ihe residt can be that the new' 

 molecule is either greater, or smaller than, or has happened to remain 

 e(iual to half the volumes of Ihe two molecides. Ihe atoms of which 

 have been exchanged. But we do not \ct know the degree of the 

 variability . 



But let us aftei- these speculative considerations return to the 

 investigation whether also other observations about the critical circum- 

 stances are in agreement with the values of C and H, which we 

 have calculated above for the case of mutual binding. 



It had already drawn my attention that for isopentane had 



Pk 



been found somewhat smaller than for normal pentane, and that, 

 if this should also be the case for other iso-compounds, the earlier 

 calculations, in which these differences were not found, could not 

 be quite accurate. And strictly speaking already in the earlier calcu- 

 lation it can be pointed out that there are dilferences which have 

 been neglected in this calculation. The volume for all atoms C e.g. 

 was put equal, though there always exist 2, viz. the outmost of the 

 chain, which are bound to 3 atoms H and 1 atom C, whereas there 

 ai-e n — 2 atoms C, which are bound to 2 atoms H and 2 atoms C, 

 and which will accordingly be smallei- than the 2 outmost. For the 

 iso-compounds the case may even present itself that an atom is bound 

 to 1 atom of H and 3 atoms of C, and perhaps even that one atom 

 of would be bound to 4 atoms of C. I was therefore glad that 

 for a few iso-compounds the quantities Tk and jtk are determined 

 through investigations by Sydney Young — viz. for di-isopropyl 

 and di-isolutyl. For the former substance, for which, if the construc- 

 tion is disregarded, the composition is the same as that of Hexane, 



T 



—^^ = 16.3, and for the latter, the composition of which would be 



equal to that of Octane, — is equal to 22.4. For normal compounds 



pk 



the values are 17,06 and 23,1 in the above list. Also for these 

 compounds the case occurs that the volume is smaller than for 

 noiinal ones, and even not inconsiderably. 



But on account of the incertainties as to in what way and to 



