OCTOBEE 14, 1904.] 



SCIENCE. 



497 



seem, however, that the great difference 

 between the intense chemical activity of 

 triphenylmethyl and the comparative inac- 

 tivity of ethylene demonstrates that, if the 

 latter does in reality have free valences, 

 the fact that there are two such valences 

 reduces the activity of each enormously. 

 The inactivity of carbon monoxide may be 

 significant in this connection. 



A more serious objection to Pfeiffer's 

 hypothesis lies in the fact that he supposes 

 so slight a difference in the configuration 

 of fumaric and of raeemic acids that it 

 is difScult to see why the former as well 

 as the latter might not be split into a pair 

 of optically active bodies. 



"We must admit, then, that we have, at 

 present, no satisfactory theory of double 

 and triple unions and that we have here a 

 problem which demands a large amount of 

 further work before it is solved. When 

 the solution is reached we shall probably 

 gain a new insight into the perennial ques- 

 tion of the structure of benzene, and our 

 knowledge of tautomerism will cease to be, 

 as it is at present, almost purely empirical. 

 It is possible, perhaps probable, that 

 Thiele's 'conjugated double unions' will 

 contribute toward the solution. 



While I have no comprehensive theory 

 with regard to double unions to advance, 

 I will, with a good deal of hesitation, ven- 

 ture to express some thoughts with regard 

 to the combination of atoms in general 

 which have some bearing on this question. 

 We are all familiar with Faraday's law 

 that if a current of electricity is passed 

 through a number of cells filled with solu- 

 tions of different electrolytes and arranged 

 in series, exactly equivalent amounts of 

 the various components will be liberated at 



pears to.be more important and more conclusive 

 than the physical. It is probable that the 

 doubled physical molecule is the result of forces 

 which do not produce a stable structure in the 

 ordinary sense. 



the electrodes in the successive cells. The 

 beautiful experiments of Professor T. W. 

 Richards have demonstrated that we are 

 dealing here with a law which is true for 

 different solvents and over a wide range 

 of temperature; and also that the law is 

 true with a degree of absolute accuracy 

 which is of the same order as the laws of 

 the combination of elements by weight. 

 We are compelled, then, to believe that 

 there is associated with each valence of an 

 ion as it is transported through a solution, 

 or at least as it separates at an electrode, 

 a quantity of electricity which is invaria- 

 ble and independent of the nature of the 

 ion. In other words, we have here a natural 

 electrical unit which can be defined in its 

 relation to atomic weights with a degree 

 of accuracy which seems to be limited only 

 by the refinement of our manipulations. 



It is not always recognized as clearly as 

 it should be that this unit quantity of elec- 

 tricity which is associated with one valence 

 of any ion is not a unit of electrical energy. 

 If it were, the same energy would be re- 

 quired to decompose the equivalent quan- 

 tity of one electrolyte as of every other, 

 which is manifestly not true. While the 

 same current causes the separation of 

 equivalent quantities in the different cells, 

 the differences of potential, and so the 

 amounts of energy required for the separa- 

 tion, vary greatly. It is evident then that 

 when we say that a unit quantity of elec- 

 tricity is associated with each valence of 

 every ion we do not use the term quantity 

 in the sense of quantity of electrical energy. 

 Instead of this, when this conception of a 

 unit quantity of electricity is examined it 

 will be seen that it is a conception of some- 

 thing whose properties are those of matter 

 rather than those of energy. The facts ap- 

 pear to be consistent with the idea that the 

 unit quantity of electricity of which we 

 are speaking is of a material nature and 

 you have doubtless already perceived that 



