740 Spectrum Analysis . [December, 
and Kirchhoff, allows that “ certain metals— calcium, 
barium, and strontium— yield spedtra of two kinds ; one of 
these, seen at the lower temperature, and consisting of 
broad bands, being resolved at a higher temperature into 
bright lines. These bright lines . . . characterise the true 
metallic spedtrum, while the band spedtrum is probably pro- 
duced by the incandescent vapour of a metallic compound.” 
The same chemist observes further that “ it has been stated 
that all the various forms of carbon-compounds, when in the 
state of incandescent gas, yield identical spedtra. This 
proves not to be the case.” 
Notwithstanding the difficulties adduced — which, on being 
more accurately examined, seem calculated rather to lead to 
new and important discoveries than to discredit those already 
made, or to permanenly invalidate the method to which they 
are owing,— the method of spedtrum analysis prepared and 
pointed out as important by many a previous investigator, 
and brought into prominent notice by MM. Kirchhoff and 
Bunsen, is certainly a most valuable accession to the che- 
mical philosopher. In fairness it should also be stated that, 
although the researches of the two distinguished professors 
had been, in almost every respedt, anticipated by others, yet 
such was the indecision prevalent on the subjedt before their 
own publications that a physicist of such great eminence as 
Sir D. Brewster — to whom optical science owes almost in- 
numerable discoveries, and who, in 1842, had himself for the 
second time made observations on this very matter of the 
colouration and spedtra of flames— gave out in i860, when 
MM. Kirchhoff and Bunsen’s memoirs were yet unknown in 
England, that, besides in that of soda, the “ ray [D] is 
prominent also, according to W. A. Miller, in the flames of 
lime, strontia, baryta, zinc, iron, and platinum, and, ac- 
cording to Angstrom, in the eledtric flame of every metal 
examined by him.” Yet the great stir which, upon the 
introdudtion of the new method, ensued in the scientific 
world, was perhaps in no small measure owing to its acci- 
dental connedtion with another series of researches, some 
account of which we now proceed to give. 
Wollaston, in 1802, noticed for the first time that the 
solar spedtrum was interrupted by seven black lines, five of 
which he took to indicate the limits of the four (assumed) 
primary colours. Fraunhofer, in 1815, with superior appa- 
ratus, of his own make and invention, numbered about 600 
such lines, some 350 of which he laid down in his celebrated 
map of the solar spedtrum. The light of the moon, of 
Venus, and of Mars, according to Fraunhofer’s observations 
