CHEMISTJIY. 647 



trum of the latter; tbis holds even in a mixture of 43 parts samaria 

 and 57 parts yttria. The delicacy of the spectrum test for samarium 

 is extraordinary; a mixture of 1 i)art of samarium with 1,000,000 parts 

 of calcium still exhibits a feeble spectrum of samarium ; in a mixture of 

 1 to 2,500,000 parts the spectrum of samarium is nearly imperceptible. 

 A striking feature in the spectra of various mixtures of samaria and 



yttria is a brilliant and sharp orange line -2693. So long as this bright 



line is a component of the spectrum the other bands manifest decidedly 

 less intensity, and many of them are suppressed. The profound modi- 

 fication in the spectra of samaria and yttria developed by their mixture 

 IS undoubtedly without precedent in spectrum analysis. Mr. Crookes 

 remarks in conclusion that the many anomalies unearthed in these re- 

 searches teach that inferences drawn from spectrum analysis per se are 

 liable to grave doubt, unless at every step the spectroscopist goes hand 

 in hand with the chemist. Spectroscopy may give valuable indications, 

 but chemistry must after all be the court of final appeal, (Chem. News, 

 LI, 301.) 



A New Kind of Metallic Spectra, ; Possible Neic Elements. — At the 

 meeting of the French Academy of Sciences on June 8, 1885, M. Lecoq 

 de Boisbaudran requested that a sealed packet which he had deposited 

 June 30, 1884. might be opened. The packet was opened by the per- 

 manent secretary during the meeting and contained a note of which 

 the following is a condensation. When the electric spectrum of a solu- 

 tion with a metallic base is produced, it is customary to make the outside 

 platinum wire (whence the induction spark strikes) positive, the liquid 

 consequently forming the negative pole. If the direction of the current 

 be reversed, the metallic rays, due to the free metal or to one of its com- 

 pounds, are scarcely visible or quite invisible, at all events so long as 

 the exterior platinum wire now forming the negative pole is not coated 

 with a deposit. In examining the rare earths belonging to the didymium 

 and yttrium family, the writer observed with many of the preparations 

 the formation of spectrum bands, nebulous but sometimes tolerably 

 brilliant, having their origin in a thin layer of a beautiful green color, 

 which was seen to appear at the surface of the liquid (a solution of a 

 chloride) when it was rendered positive. The principal bands are six 

 in number, situated as follows : A620^, A585|, A573, A543|-, A487, A476J; 

 some of these are nebulous and broad. That at 543^ is probably not 

 due to any known element, unless it proves to be due to holmium. That 

 at 573 is also probably due to a new element. The latter yet unisolated 

 body the author designates provisionally by Za, and the former by Z/3. 



M. Lecoq de Boisbaudran regards his " reversion spectrum " as phys- 

 ically analogous to the phosphorescent spectra obtained by Mr. Crookes 

 at the positive pole in his high vacuum tubes containing certain com- 

 pounds of yttria. [See our Keport for 1883.] 



