A DREAM OF FAIR HYDRONE 495 



the group (C 6 H 5 ) 2 I exercising the functions of the atom of sodium 

 in sodium hydroxide. Such are the wonders of chemistry ! 



To carry the argument one stage further : the compound 

 (CH 3 ) 3 SC1, in which sulphur functions as a tetrad, contains only 

 two different radicles. If in place of the three similar hydro- 

 carbon radicles three which are different be associated with a 

 sulphur atom, optically active compounds are produced, as in 

 the case of carbon. In this way proof is obtained that sulphur 

 can simulate carbon : the tetrahedron becomes the model of the 

 sulphur atom as well as of the carbon atom. And since oxygen 

 is very closely related to sulphur, it may be assumed that 

 oxygen also can exercise " tetrahedral" functions and that it 

 may be expected to behave more or less like carbon. In not 

 a few cases it does. Thus a number of compounds are known 

 in which four atoms of carbon are associated with one atom 

 of oxygen m a ring. Such rings are formed with exceptional 

 readiness, so that it would seem to be probable that the 

 directions in which the affinities of the oxygen atom act 

 naturally are not very different from those in which the affinities 

 of carbon act. But such arguments must not be pressed too 

 far ; the depth of our inability to account for the peculiar loves 

 and affinities of the atoms must not be forgotten. 



Epilogue 



We may now ask, How is liquid water itself formed from 

 hydrogen oxide ? What "may we suppose the composition 

 and constitution of liquid water to be? Its properties are 

 altogether incompatible with the assumption that it consists 

 only of simple molecules such as are represented by the 

 formula H 2 ; and yet, as steam consists of these, such simple 

 molecules must be present in it, as the maintenance of equili- 

 brium between a liquid and its vapour necessarily involves the 

 constant passage of gaseous molecules from and into the liquid. 



To mark the distinction between liquid water and the 

 fundamental molecule represented by the formula OH 2 from 

 which it is formed, it is desirable to confine the term " water " 

 to the liquid and to term the fundamental molecule Hy drone} 



Hydrone is comparable with the hydrocarbon radicle 

 methylene, CFL, which, however, cannot exist perse, its affinity 



1 Compare Royal Society Proceedings, 1908, A, vol. 81, 80. 



