THE 
JOURNAL OF SCIENCE. 
DECEMBER, 1880. 
I. SPECTRUM ANALYSIS. 
By Dr. Akin. 
t ^T has been truly said of Dr. Young’s “ Course of Lec- 
tures on Natural Philosophy,” delivered at the Royal 
Institution (it is to be feared before a somewhat unap- 
preciating audience) in the first years of this century, that it 
contains the germs of many more discoveries than can be 
found foreshadowed in any other single extant book. In 
p 438 of the first volume of that invaluable work (ed. of 
1807) the author observes “ In light produced by the 
combustion of terrestrial substances the spedtrum is still 
more interrupted ; thus the bluish light of the lower part of 
the flame of a candle is separated by refradtion into five 
parcels of various colours ; the light of burning spirits, 
which appears perfedtly blue, is chiefly composed of green 
and violet rays, and the light of a candle into which salt is 
thrown abounds in a pure yellow, inclining to green, but 
not separable by refraftion. The elearical spark furnishes 
also a light which is differently divided in different circum- 
stances.” Of this passage it may be asserted that it con- 
tains the germ, although it has not aaually formed the 
starting-point, of researches which, prosecuted at first in a 
desultory manner, have since, after the lapse of half a 
century, given rise to a series of discoveries which must be 
classed’among the most striking, if not altogether among 
the most novel, of our age. The above statement by Dr. 
Young was neither absolutely the first nor the only fore- 
runner of those discoveries. It is said that already, “ in 
1752, Melville observed the effedt of soda on flame and 
VOL II. (THIRD SERIES). 3 A 
