SCIENTIFIC INTELLIGENCE. 



I. PHYSICS AND CHEMISTKY. 



1. Contributions to the Spectral Analysis.—ln examining with the spec- 

 troscope a substance containing baryta, A. Mitscherlich observed two bright 

 green bands which appeared to indicate the presence of a new njetal. 

 ^ti further investigation it was found that the same lines were obtained 

 sometimes alone, sometimes together with barium lines, when a solution 

 of chlond of barium containing sal-ammoniac is employed. By means 

 or a smiple apparatus, consisting essentially of a glass tube closed at its 

 lower end by a bundle of fine platinum wires and filled with the liquid to 

 oe examined, the author obtained colored flames of great intensity and 

 !^"? ^^"'■^'•ion» the wires serving by capillary action to feed the flame of 

 the burner, A mixture of 1 part of a concentrated solution of chlorid 

 of barium with 20 parts of a solution of sal-ammoniac and 20 parts 

 ot chlorhydric acid containing about 20 parts of real acid gives the 

 two green lines above mentioned. By employing solutions of the clilo- 

 n:Js of calcium or strontium mixed with sal-ammoniac, new spectra are 

 obtained which differ greatly from the ordinary spectra, but which are 

 seldom quite free from them. Even to the eye alone the new flames differ 

 in color from those obtained by employing the metallic salts without the 

 addition of sal-ammoniac. From this it follows that the spectrum of the 

 inetals of the alkaline earths, is difl'erent from that of their chlorids. That 



01 tills ditterence, is shown by the fact that the ordinary or metallic spec- 

 tra are not changed by passing the light through a flame containing 

 sal-ammoniac. The spectra of protochlorid and subchloiid of copper 

 ^ere found to be diS'erent though usually more or less mixed in conse- 

 quence of the reduction of the chlorid to'subchlorid by heat. By intro- 

 oucing several substances into the same flame particular lines often vanish ; 

 thus the blue strontium line disappears when chlorid of coprM?r, sal-am- 



n^oniacand chlorid of stront ' ' "^ ' 



and sodium give no spectra a 



^hen the chlorid is mixed with sal-ammoniac and chlorhydric aciu. ine 

 sodium reaction is too delicate for this experiment, but the author found 

 "lat light transmitted through the vapor of the ignited chlorid gave no 



From the above it follows that the metals do not give a spectrum ia 

 ^'1 their compounds, and that they do not give the same spectrum in dif- 

 ferent compounds, but that the character of the spectrum depends upon 

 J'hether it is produced by the metal or by one of its compounds of the 

 nrst order. It further appears that every compound <rf the first order, if it 

 have jj spectrum other than that produced by decomposition, roust have a 

 spectrum of its own. Metallic compounds are so easily reduced by the 

 ""^ ' ■' the spectra of the metals themselves. 



•^%bt passed through ignited sod 

 soda, does not give the sodium lii 



the^sodium line D, but the vapor of metallic sodium 

 XXXIV, No. It^— Noy.,I8C2. 



