140 Atomic Weights of Silver and Copper. 



densities, and is correspondingly lower. At any rate the 

 results point to a limiting value for the ratio differing very 

 little from 3-4000. 



Now if the atomic weight of copper be taken to be 63*18, 

 as determined by purely chemical methods, the ratio would 

 be, as stated above, 3*4080. This is the ratio obtained, as the 

 result deduced from the experiments I am referring to, when 

 the current-density is *0085 ampere per square centimetre. 

 The variation with current-density is, however, quite con- 

 tinuous through that value ; and there seems to be no good 

 reason for supposing that there are a number of secondary 

 actions which exactly balance each other at that value. More- 

 over the number 3*400 lies well within the possible limits 

 3*381 and 3*435, assigned in Landolt and Bornstein's table. 



Accepting, then, the value of the ratio of the chemical 

 equivalents of silver and copper as 3*4000, it follows that the 

 ratio of the atomic weight of silver to that of copper is 17 : 10; 

 and if the atomic weight of silver be 107*66, the atomic weight 

 of copper is 63*333. These two numbers are evidently thirds 

 of whole numbers, and we get the following numerical rela- 

 tions, which are somewhat remarkable : — 



a m7«« 323 17 >< 19 

 Ag = 107-66= -g- = — 3 — , 



n „ aa 190 19x1 

 Ou = 63*33=— ^- = o — 9 



Ag_17 



Cu - 10* 



There are many lines of speculation which start from the 

 grouping of whole numbers suggested by these results. For 

 instance, if we refer the atomic weights to a unit which is one 

 third of the weight of the hydrogen atom, the numbers for 

 silver and copper are whole numbers resolvable into factors. 

 The resolution of the numbers into factors may correspond to 

 the different valencies of the elements : thus the only possible 

 valencies for silver would be 1, 17, and 19 ; for copper, 1, 2, 

 5, and 19. The several groups might then be regarded as 

 practically separate atoms, each associated with the same 

 charge of electricity in electrolysis as is always associated with 

 a monad atom. The valencies 1 for silver and 1 and 2 for 

 copper do actually occur. If the atomic weight of oxygen 

 referred to this unit be regarded as 48, the number of possible 

 valencies would be very great ; and the same may be said of 

 carbon, with the atomic weight 36 referred to the same unit. 



