MR. W. CROOKES ON RADIANT MATTER SPECTROSCOPE. 
717 
on the horizontal line show the actual mixtures experimented with (146 to 149). 
The part to the left covers the mixtures showing a preponderance of the samarium 
spectrum, and the right-hand portion shows the mixtures which give preponderance 
to the yttrium spectrum only. The intermediate portion covers the narrow border¬ 
land in which the fainter mixed spectra were observed. 
In no mixture does the resulting spectrum contain the complete spectrum of either 
earth, many bands of each being suppressed. 
154. It was of interest to ascertain whether the orange line 2693 could be evoked 
by mechanically forming a mixture which, when prepared chemically, gave the line 
strongly. 
A radiant matter tube was made in the form of a double bulb, as shown in Fig. 11. 
Fig. 11. 
In one half was introduced ignited samaric sulphate, and in the other half the same 
weight of yttric sulphate, each being finely powdered. The tube was well exhausted 
and the powders separately examined with the spectroscope. Each gave its charac¬ 
teristic spectrum (72, 137). The double bulb was now sealed off, and the powders 
well mixed by violent agitation. On careful examination it was seen that the 
spectrum shown by the mixture was simply that of the two components superposed, 
and had no resemblance to the spectrum shown by a similar mixture prepared by 
solution and chemical action (fig. 13.) 
The Action of Calcium on the Samarium-Yttrium Spectrum. 
155. The addition of calcium to mixtures of samarium and yttrium has the effect 
of greatly developing the samarium spectrum, and, pari passu, of impairing the 
sharpness of the bands of the yttria spectrum. This exaltation of the samarium 
bands is not, however, effected without a corresponding loss. The brilliantly sharp 
orange line 2693 entirely disappears. 
Fig. 12 is a drawing of the spectrum given by a mixture of equal parts of samaria, 
yttria, and lime. On comparing it with fig. 13, which represents the spectrum given 
by the same mixture without the lime, it will be seen that the action is as might have 
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