240 Intelligence and Miscellaneous Articles. 



Chloride of Cobalt. — The flame very much resembles the pre- 

 ceding. The upper spectrum is continuous, and fairly bright ; the 

 lower shows three faint lines in the violet and the extreme violet 

 (y, 0, and n of the electric spectrum). 



Chloride of Zinc. — Nothing more than a feeble continuous lumi- 

 nosity in the upper spectrum ; the lower shows pretty clearly the 

 violet line a of the electric spectrum. 



Chloride of Cadmium. — Nothing in the upper spectrum ; the 

 other presents a feeble violet line, /3 of the electric spectrum. 



Nitrate of Manganese. — There is nothing particular in the upper 

 spectrum ; the lower shows a group of three feeble violet lines, a 

 of the electric spectrum. 



Nitrate of Copper. — The upper spectrum shows several bands ; 

 one of them, in the red, is notably reinforced in the lower spectrum. 



Nitrate of Lead. — Nothing in the upper spectrum ; the other 

 presents a very distinct line in the extreme violet, a of the electric 

 spectrum. 



Nitrate of Silver. — Nothing in the upper spectrum ; the other 

 shows two well-marked lines, a and (3 of the electric spectrum. 



Chloride of Platinum. — The flame is of a bluish whiteness ; its 

 illumination is equal to that of a wax taper. The upper spectrum 

 shows a continuous bright luminosity, with some feeble bands and 

 lines. The lower does not resemble the electric spectrum ; it is 

 formed of a fine series of sufficiently brilliant bands, less bright on 

 the side towards the red, their other edge being clean ; a few fainter 

 lines are also seen. 



Of the other metals, some have not been submitted to experi- 

 ment, and others have not given any clear results. 



The spectra above described were observed with flames in some 

 degree reducing. On charging the flame with gas the interior cone 

 lengthens, and its spectrum becomes less bright without changing 

 its nature. "With a large excess of air the cone changes its form, 

 dividing into violet points, sometimes very tall. At this moment 

 the lines of carbon have disappeared, save that in the violet ; they 

 are replaced by a continuous ground, on which the metallic lines, 

 enfeebled, detach themselves. The flame properly so called is 

 almost invisible, and shows scarcely a trace of the sodium-line ; 

 but it becomes visible and coloured green when it contains copper. 



In brief, we have seen that the base of the flame gives, over a 

 very small elevation, a spectrum which approaches the electric 

 spectrum of the same metal ; I purpose to extend these researches 

 to other flames. 



I will remark in conclusion, that in the usual spectral analyses 

 a mixture of both spectra (of the cone and the flame) is seen ; 

 therefore the relative intensity of the lines must change according 

 to the part of the flame which is viewed, as Lecoq de Boisbaudran 

 has observed for the chloride of manganese*. 



This investigation was made in the laboratory of M. Desains, 

 at the Sorbonne. — Comptes Rendus de V Academic des Sciences, Jan. 

 29, 1877, tome lxxxiv. pp. 231-234. 



* Spectres Lumineux, p. 122. From this work we have borrowed the 

 letters assigned to the lines. 



