CHEMISTRY. 435 



With the specially piirirtedzinc and the same concentration of acid both 

 gases are given off in (luantity at 163'^. The dependence of the produc- 

 tion of these gases upon temperature and concentration seems to indi- 

 cate that they are not altogether generated by any reducing action of 

 nascent hydrogen upon sulphuric acid. The authors regard the inter- 

 action in the case of pure zinc and acid as chiefly chemical, and ascribe 

 the products evolved by less i)ure zincs to secondary electrolytic 

 changes. Doubtless the actual re-actions are more comi)lex than cau 

 be shown by any system of equations at present. ( Journ. Chem. Soc, 

 Liii, 47.) 



Ahsorptio)i spectra of the rare earths. — Kriiss and Nilson, studying 

 the rare earths from thorite, wohlerite, cerite, fergusonite, euxenite, etc., 

 have discovered various anomalies in tlieir al)sorptiou spectra which 

 they ascribe to a greater elementary complexity than has commonly 

 been recognized. In place of the so called erbium, holmium, thulium, 

 didymium, and samarium, they assume the existence of more than twenty 

 elements, each of the above-named substances giving spectra which 

 vary for each substance with differences of origin. For example, in the 

 earths from thorite, all the lines ascribable to holmium were seen, but 

 all faintly except one. That one, which was strong, is ordinarily oneof 

 the faintest. The lines which are commonly strongest were barely vis- 

 ible. Of earths from fergusonite a series of fractionations was made, 

 and in these similarly curious anomalies were noted. In certain por- 

 tions some lines belonging to a given element would appear, and others 

 would bo wanting, and thus the supposed element was shown to be pre 

 sumably a mixture. For details, with wave lengths of the lines, the 

 original paper must be consulted. (Berichte, xx, 2134.) 



To the foregoing conclusions of Kriiss and Nilson, Bailey objects. 

 As regards the relative intensity of absorption lines, he holds that the 

 several spectra in a mixture of eartlis modify each other, the propor- 

 tioned quantity of each earth affecting the jiroblem decidedly. A strong 

 absorption band may hide a weaker one, and furthermore, differences 

 of dilution with respect to any given oxide will intiuence its s[)ectrum. 

 Variations may also be due to the presence of reagents ; as for instance, 

 as nitrate solutions were studied, an excess of nitric acid. (Berichte, 

 XX, 2709.) 



To Bailey's objections, Krii.ss and Nilson publish a rejoinder, in which, 

 with other evidence, they state that their solutions (;ontaiii(Ml only neu- 

 tral nitrates of the earths. (Berichte, xx, 3007.) Later, Bailey rej)lies, 

 leaving the question still in doubt. (Berichte, xx, 3325.) The discus- 

 sion is continued in Berichte, xxi, pj). oSi}, 1521, and 2010, and fur- 

 thnr spectral investigations by Kiesewetter and Kriiss api)ear in the 

 same volume, p. 2310. In the latter paper the earths from keilhauite 

 and gadolinite are studied with results analogous to those given in the 

 first of the above-cited publications. 



Elements and meta- element n. — In his address as president of the ( Ihemi- 



