720 
MR. W. CROOKES ON RADIANT MATTER SPECTROSCOPY. 
almost gone, being overshadowed by the continuous spectrum of calcium which has 
spread over it. The red band has likewise almost disappeared in the greater brightness 
of the continuous red of the calcic spectrum. The double orange band is still very 
prominent, and the black space, 2942, between it and the green is very marked. 
161. The next mixture, 1 part of samarium to 500,000 parts of calcium, gives a 
spectrum which is fainter than the last, but the orange bands are still distinctly 
Fig. 19. 
visible. The black space between the yellow and green is strongly marked, but 
narrower than before. Fig. 19 shows the appearance of this spectrum. 
162. A mixture of 1 part of samarium in 1,000,000 parts of calcium was next 
subjected to experiment. In this the samarium spectrum is very feeble, and the 
Fig. 20. 
orange bands are only to be seen with difficulty. Now the most striking characteristic 
of this spectrum is the black space which still cuts out the greater portion of the 
yellow. Fig. 20 represents this spectrum. 
163. A mixture of one of samarium in 2,500,000 parts of calcium was now taken. 
Fig. 21. 
In the spectrum shown by this mixture the bands of samarium have entirely gone, 
and its presence now is apparent only by the darkening in the yellow portion of what 
otherwise would be a continuous spectrum. Fig. 21 shows this appearance. 
