500 Hachh — Modification of the Periodic Table. 



4. In establishing a more rigid form of the periodic 

 system these elements (He, Ne, A, Kr, X, Nt) are used as 

 the starting and ending points of the periods ; between 

 these terminals the properties change periodically, and 

 the more elements there are between (fifth period), the 

 less characteristic is the change. This accounts for the 

 formation of such groups as Fe-Co-Ni, Ru-Rh-Pd, Os-Ir- 

 Pt, and the rare earths. 



5. The periodic system is best expressed in a con- 

 tinuous curve, e. g., spiral. But as such graphic repre- 

 sentations are difficult, a table has been derived which 

 shows the relationship among the elements better than 

 the customary table. A number of characteristic fea- 

 tures of the table have been pointed out and the rule 

 established that: The Similarity among the elements 

 in the upper half of the table is in a vertical direc- 

 tion, while the similarity among the elements in the lower 

 half is in a horizontal direction. 



6. The term affinity is vindicated, when its use is 

 restricted to a characteristic tendency of the elements in 

 a certain area of the new periodic table. 



7. A table showing the close relationship between 

 polar number and isomorphism is presented. 



8. The periodicity of the specific gravity is shown in 

 Table V and the allotropic forms of the elements are 

 introduced into the periodic system by Table VI, repre- 

 senting a section of the main table. An accumulation of 

 more facts regarding the allotropic forms of other ele- 

 ments will justify an enlarged table, giving also the tran- 

 sition points. 



9. A condensed system of the radioactive elements has 

 been constructed (Table VII) which can be used as an 

 appendix to the main table (Table VIII). 



Berkeley, California. 



EEFEEENCES. 



1 Chem. News, 13, pp. 113 and 130, 1866. 



2 Ann. Chem. Pharm., 7, 354, 1870. 



3 Journ. Euss. Phys. Chem. Ges., 1, pp. 60 and 229, 1869. 



4 Chem. Zeitg., 19, p. 2164, 1895. 



5 Z. anorg. Chem., 9, pp. 190 and 283, 1895. 

 6 Ber., 31, p. 3111, 1898. 



7 Z. anorg. Chem., 18, p. 72, 1898. 



8 Die Grenzen des periodischen Systems, Belgrad, 1906, and Ion, 1, 259, 

 1910. 



