PHYSICAL CHEMISTRY 541 



the nitrates of lutecium from the gadohnium earths, obtained 

 the oxide of a new element, which gave a characteristic line 

 spectrum. Very little is known of its chemical properties, 

 except that it is probably a rare earth. The volatility of its 

 anhydrous chloride and the strength of its base are inter- 

 mediate between the corresponding properties of the com- 

 pounds of lutecium and scandium. To this element Urbain 

 gave the name Celtium (Ct). Dauvillier, while studying the 

 L-series of lutecium and ytterbium, discovered two feeble 

 Hues, /32= 1319-4, and 01=1561-8, which agreed with an 

 atomic number 72 for the new element. Urbain {C.R., 1922, 

 174, 1349-51) considers that Dauvillier's work definitely 

 establishes the position of celtium in the periodic table. 



J. Maria Eder {Sitzungsb. Akad. Wiss. IVien, 1922, 131, 

 199-298), in the course of the examination of the spectra of 

 a number of terbium, dysprosium, and gadolinium fractions, 

 found a new element between the terbium and dysprosium 

 fractions which gave characteristic and well-defined lines not 

 previously observed for any other substance. The element 

 was named w^elsium. Its position in the periodic table is 

 not stated, but it is possible that it occupies the vacant space 

 between neodymium and samarium (atomic number 61). 



Hevesy and Coster have measured six of the L-series 

 of a missing element which occurs in zirconium minerals, 

 L-a^= 1565-5 ; a2= 1576; A= 1371-4; /32= 1323-7; ^3= 1350-2 ; 

 7i= 1 1 77 X-yLt. L-a^ and L-a^ lie almost exactly in the places 

 of the Ka^ and ag of zirconium, but the difficulty of 

 measurement was overcome by maintaining the tension of the 

 tube between the critical tension of the zirconium K lines, 

 and the L fines of the missing element. All of the lines were 

 within I X-/J. of the figures interpolated from the spectra of the 

 two elements immediately before and after the element with 

 atomic number 72. On the other hand, Dauvillier's values 

 differed from the theoretical by more than 4 X-/J.. It was 

 estimated that the new element appeared in zirconium minerals 

 to the extent of o-oi to o-i per cent. In one specimen about 

 I per cent, of the new element was present. This suggests 

 that this new element is a homologue of titanium and zirconium, 

 and hence should be tetravalent. According to the Bohr 

 theory, an element with an atomic number 72 should possess 

 one more electron in the 5 and 6 quantum orbits than the 

 rare earths. Since the latter are tervalent, it would therefore 

 be expected that the new element would be tetravalent. On 

 this account, the authors consider that the Z-series obtained 

 by them and Dauvillier cannot be those of a rare earth element, 

 and that the rare earth element discovered by Urbain must 

 possess another atomic number. One awaits with interest 



