41 G Intelligence and Miscellaneous Articles. 



need merely successively be placed at the minimum deviation for each 

 ray of the spectrum, and a hollow prism used which is filled with 

 sulphide of carbon, and closed by two parallel quartz plates. Flint- 

 glass prisms have not always the same refracting power. 



12. Lastly, with sufficient length, and in a barometric tube where 

 the vacuum is made with the greatest care, the electric current can 

 only be passed when the tension is very great ; and in this case the 

 prismatic analysis of the feeble light which passes shows that the 

 electricity can only strike through long distances by detaching- 

 metallic particles from both electrodes, and, so to speak, forming for 

 itself a bridge of material molecules. — Comptes Rendus, November 4, 

 1S62. 



ON THE SPECTRA OF PHOSPHORUS AND SULPHUR. 

 BY M. J.-M. SEGUIN. 



Phosphorus and sulphur are volatilized in a current of 'hydrogen, 

 and the sparks from a moderate-sized RuhmkorfFs machine passed 

 through the mixture of gas and vapour. The electrodes consisted 

 of fine platinum wires, covered with glass within a few millimetres 

 of the end, and at a distance of a few millimetres from each other. 

 They did not become red during the experiment. The spectrum 

 was viewed through the prism with the naked eye, which gives the 

 well-marked rays. 



The vapour of phosphorus in hydrogen gives a red ray, an orange 

 ray almost as visible as the red, two less well-marked green rays at 

 the more refrangible end of the visible part of the green, and, at an 

 interval comparatively dark, a bluish-green ray, then some blue or 

 violet rays which are not easily distinguished. The orange ray, 

 which is very bright, as well as the two feeble green rays, appear or 

 disappear according as the receiver which contains the phosphorus 

 is heated. They consequently belong to this substance. The red 

 and bluish-green rays probably belong to hydrogen. 



This experiment was confirmed in the main points by operating 

 on phosphuretted hydrogen, and on a mixture of terchloride of phos- 

 phorus and hydrogen. 



The spark in a mixture of sulphur vapour and hydrogen is of a 

 bright blue, while it is of a pale rose in hydrogen alone. In the 

 spectrum there is a red ray, and three distinct green rays almost 

 equidistant from each other. The first, and often the second, ap- 

 peared almost yellow from their lustre ; the third is slightly less 

 bright, and it extends a little on the side of the others ; it seems to 

 comprise several fine and near rays ; there are also a bluish-green 

 ray, two blue rays, and two violet rays, which form flirtings in the 

 most refrangible part of the spectrum. The three green rays are the 

 most salient part of the spectrum of sulphur. Most of the blue and 

 violet rays belong to this substance. 



The spark was also observed in sulphuretted hydrogen and sul- 

 phurous acid. The three green rays showed with such precision 

 that it was impossible to mistake their identity. — Comptes Rendus, 

 December 30, 1862. 





