^5 Spectrum Analysis. [December, 
Dr. Wollaston, in 1802, had first indicated those “ five 
parcels ” of rays in candle-light mentioned by Dr. Young, 
as well as the existence of a diversity in the spedlra of 
eledtric sparks in different circumstances. The celebrated 
Fraunhofer, in 1815, speaking rather vaguely of “ the light 
of electricity,” observed that it gave a different speftrum 
from those of “the sun and of fire;” whilst Sir H. Davy— 
viewing the subject in a much more philosophical manner — 
made, in 1822, the novel and important assertion that “the 
light generated in eledtrical discharges depends principally on 
some properties or substances belonging to the ponderable 
matter through which it passes.” In the same year Sir D. 
Brewster and Sir J. Herchel had devoted some attention to 
the investigation of the spedlra of coloured flames ; and in 
a paper by Mr. Fox Talbot,— of Talbotype celebrity,— of 
the year 1826, the author states that “ the muriate, sulphate, 
or carbonate of soda ” all gave the same yellow ray in the 
spedtrum, while “ the nitrate, chlorate, sulphate, and car- 
bonate of potash agreed in giving a bluish white tinge to the 
flame. Hence,” he continues “ the yellow rays may indicate 
the presence of soda, but they, nevertheless, frequently 
appear where no soda can be supposed to be present.” In 
fadt, “ ignited sulphur produced the very same ” rays. In 
1827 Sir J. Herschel reverted to this subjedt in his celebrated 
treatise on Light, where, after describing the colourations 
which different “ saline bodies,” “ in general,” impart to 
flames, he observes that “ the colours thus communicated 
by the'different bases to flame afford in many cases a ready 
and neat way of detedling extremely minute quantities of 
them ;” and he assigns also reasons to show that “ these 
tints arise from the molecules of the colouring-matter re- 
duced to vapour, and held in a state of violent ignition. 
Thus the matter rested for a while. In the year 1834 the 
same indefatigable Mr. Talbot made the remarkable disco- 
very that the two bases, lithia and strontia, while both 
impart a red tinge to flame, may yet be distinguished by the 
different lines visible in their prismatically analysed light ; 
in consequence of which, and of some later observations, he 
in 1836 insisted “ that an extensive course of experiments 
should be made on the spedtra of chemical flames,” as “the 
definite rays emitted by certain substances — as, for example, 
the yellow rays of the salts of soda — possess a fixed and in- 
variable character, which is analogous in some measure to 
the fixed proportion in which all bodies combine, according 
to the atomic theory.” In the same paper Mr. Talbot 
describes also the spedlra of gold, silver, zinc, and copper 
