Manchester Memoifs, Vol. Hi. (1908), No. 10 45 



Appendix. 

 On the Possible Types of Direct Chemical Combination.^ 



The question must often have arisen why chemical 

 combinations and decompositions take place on a simple 

 plan which can be represented as the addition to the 

 molecule, or removal from it, of definite blocks or com- 

 plexes of atoms, named radicles, which are therefore 

 assumed to have a transient corporate existence; so much 

 so that in a class of cases their existence has to be intro- 

 duced explicitly in order to assist as carriers in the 

 reactions. The physical analogy of an atom as a kinetic 

 system of orbitally moving sub-atoms or electrons, such 

 as is pointed to by its very definite intrinsic spectrum, 

 would lead us to expect that, as a rule, tampering with 

 the structure of a molecule by slicing off a block would 

 lead to its total dissolution : while, on the other hand, the 

 practically effective conceptions of organic chemistry 

 suggest architecture rather than dynamics. 



Some light may perhaps be thrown on this subject by 

 the consideration that it is only those structures that do 

 fall to pieces in successive stages, and are thus capable of 

 definite experimental dissection, that can have a chance 

 of being produced in quantity, and of becoming segre- 

 gated, in the clash of molecules amidst which all things 

 chemical have their origin. 



In illustration, imagine a substance, say gaseous for 

 simplicity, formed by the immediate instantaneous com- 

 bination of three gaseous components A., B, C. When 

 these gases are mi.xed, the chances are very remote of the 

 occurrence of the simultaneous triple encounter of an 



• This Appendix was included substantially in a course of lectures at 

 Columbia University, New York, in March, 1907. 



