712 
MR. W. CROOKES ON RADIANT MATTER SPECTROSCOPY. 
likewise gives scarcely any phosphorescence (137). It is, therefore, somewhat remark¬ 
able that a mixture of these two bodies should bring out the samarium spectrum so 
brilliantly. 
Magnesium and samarium give the red band and second orange band sharply ; the 
first orange is, however, obliterated, and its place occupied by a faint, broad, ill- 
defined band, extending to the orange band. The green band is very wide, faint, and 
ill-defined. 
Zinc and samarium give the red band as usual, but there is only one orange band, 
which is sharp, and occupies the position of the interval between these bands in the 
calcium and samarium spectrum. The green band is widened out, and occupies the 
position of the second green band of the thorium-samarium spectrum. 
The cadmium-samarium spectrum is similar to that of zinc-samarium, only the 
green band is still wider, and extends further towards the red end. 
144. Lead with samarium gives a very brilliant spectrum. The red is clear and 
sharp, and has a narrow faint wing on each side. The orange is one wide band, with 
no trace of division, whilst the green is sharp and duplicated as in the thorium- 
samarium spectrum, to which, indeed, it bears a great resemblance. The centres of 
the green bands are at ^ 3133 and 3199. 
Lanthanum and samarium phosphoresce brightly, and give a very sharp spectrum 
consisting of three bands, closely resembling the zinc-samarium spectrum ; the red, 
however, not being so bright as the other two bands. On the contrary, cerium or 
didymium mi xed with samarium gives no phosphorescence. 
Aluminium and samarium give a spectrum resembling the corresponding calcium 
one as to the red and double orange, but having a very broad, somewhat faint, green 
band, with a black division in the middle occupying the position of the bright green 
band of calcium-samarium. 
Bismuth and samarium gave a somewhat faint spectrum, almost identical with the 
lanthanum-, zinc-, cadmium-, and glucinum-samarium spectrum. 
The antimony-samarium spectrum is almost identical with that with bismuth, the 
spectrum being, however, much fainter. 
145. The samarium spectra, modified by other metals as above described, may be 
divided into three groups. The first group comprises the spectra given when 
glucinum, magnesium, zinc, cadmium, lanthanum, bismuth, or antimony is mixed 
with the samarium. It consists simply of three coloured bands, red, orange, and 
green; as a typical illustration I will select the lanthanum-samarium spectrum (fig. 5). 
The centres of tlie bands are—red 2429, orange 2808, and green 3177. 
The second type of spectrum gives a single red and orange and a double green 
band. This is produced when barium, strontium, thorium, or lead are mixed with 
samarium. The lead-samarium spectrum (fig. 6) illustrates this type. The centres of 
the bands of this spectrum are—red 2437, orange 2830, green 3133 and 3199. 
