SPECTEA OF THE METALS. 
881 
three intense groups of dots between 122 and 131, beyond which it gradually fades till 
it is lost at 160‘0. (Fig. 21.) 
45. Manganese. — This spectrum is well-marked. A double group of dots appears at 
107, then five strong groups of dots and lines between 119'4 and 135’5 ; the first is the 
most intense, and the last group is broad and complicated : beyond this the impression 
becomes gradually fainter, and disappears at about 152‘0. (Fig. 22.) 
46. Iron. — The spectrum of iron is intense, particularly in the more refrangible portion. 
Between 113 and 124 are three ditfused groups of dots of moderate intensity; at 126 
is a very intense group ; then a series of numerous intense groups of dots, which termi- 
nate at 154; at 155-5 a series of fainter groups recommences, and fades away at 
about 162. (Fig. 23.) 
47. Cohalt. — The spectrum of cobalt is very like that of iron in its general appear- 
ance ; but it shows two or three rather strong groups of lines between 106 and 109 ; an 
increase of intensity commences at about 128, and is continued in a series of groups of 
very strong dots, the most intense of which are situated between 134 and 147 : the 
spectrum terminates rather suddenly at about 163. (Fig. 24.) 
48. Nickel. — This spectrum is not so intense as either that of iron or of cobalt, but it 
is like them in its intensity being greater near the more refrangible extremity (fig. 25). 
It is a very long one, extending to about 190, and exhibits an arrangement of groups of 
dots at its more refrangible end, resembling that of silver, but prolonged much further. 
49. Cadmium. — This is a striking spectrum. The action is accumulated into intense 
bands with perfectly dark intervals. Two broad strong groups of lines occur at 105 
and 107, then two other compound bands or groups of dots, one on each side of the 
nitrogen line 110-5 ; beyond this are two fainter lines, then at 118 and 121 two broad 
groups of dots, frequently prolonged into lines ; at 126-3 a very strong group of dots, and 
another at 133-5 ; beyond this an almost entire cessation of action till it is resumed by 
three groups of dots, the first and last of which are the strongest in the entire spectrum. 
These groups commence at 149-5 and terminate at 155-5; beyond these are two other 
detached groups at 162-5 and 167, where the spectrum terminates abruptly. (Figs. 26 
&42.) 
50. Zinc. — This spectrum is equally characteristic with that of cadmium. Between 
109-5 and 112-5 is an intense double group of eight or nine distinct lines, then several 
well-marked lines in the interval between these and another double group, which com- 
mences at 125. An interval of diminished action follows; and then between 135 and 
140 are two intense groups, the strongest in the spectrum. These are followed by a 
few feeble groups of dots, after which is a complete interval ; and the spectrum termi- 
nates with four groups of equidistant lines, the first commencing at 167-5, the latest 
terminating at 183. (Fig. 27.) 
51. Magnesium. — This is another remarkable spectrum. An intense group of lines 
commences at 101 ; at 115 a bright group of dots is seen, and between 119 and 126-5 
are three remarkably intense groups of lines: the first of these comprises at least four strong 
