of the Periodic Systeyn of the Elements, 279 



Cu, Zn, Ga, the " positivity " first increasing then decreasing 

 (a maximum occurring somewhere between Cu and Zn), 

 then follow elements becoming more and more negative, As, 

 Se, Br. Ti and Ge ease the passage through the zero-point. 

 In the remaining periods we have a complete analogy with 

 the second ; it will be sufficient, therefore, to consider this 

 period a little more closely. 



Let us express the general connexion between e and p by 

 e=¥(p) > and let us regard e and p as rectangular coordinates 

 of a point in the plane e, p ; then e — F(p) is the equation of a 

 periodic curve. As we do not know any numerical values of e, 

 it is only possible to form some opinion as to the shape of the 

 curve by our knowledge of the properties of the elements. 

 If we assume that e= +00 between CI and K, Br and Rb, 

 I and Cs, &c, as F. Flawitzky and J. Thotnsen assume, then 

 we conclude that our curve must consist of as many separate 

 parts as there are periods of elements. But, as we know, the 

 periods are unequal ; thus, for the elements of the second, 

 third, and fifth periods the number 48 (atomic-weight units) 

 fits, whilst for the caesium-period this number seems to be 

 1*5 times too great. Hence we see that the separate portions 

 of the curve cannot be identical ; only in form do they re- 

 semble each other. 



The curve (fig. 1) drawn with two asymptotes, agrees with 

 the properties of the elements of the second period ; for the 

 following periods we have exactly similar curves, each con- 

 sisting of six portions, AB, BC, CD, DE, EF, and FG. 



We remark next that the analogous elements are represented 

 by the points of the corresponding portions of the curve ; thus 

 upon the portion AB we have the positive elements 



K, Ca, Sc, 

 Rb, Sr, Y, 

 Cs, Ba, La, Ce, 

 - -, Yb, 



the transition elements Ti, Zr, Di (?), — , Th (?) corresponding 

 to the point B. 



From the properties of V, Cr, Mn we may further conclude 

 that these elements are represented by the points of the 

 portion of the curve CD ; thus upon the portion CD we have 

 the negative elements 



V, Cr, Mn, 



Nb, Mo, — , 



Di?,-, -, 



'J a, W, -, 



- u, -, 



