MR. W. CROOKES ON RADIANT MATTER SPECTROSCOPY. 
701 
being extraneous to the earth itself. In some instances, however, the spectrum 
increased in intensity ; moreover, when the purified earth showed any diminution of 
the orange band the eliminated impurity always showed the orange band in an exalted, 
degree. I drew from these experiments the inference that x was a definite element, as 
widely distributed, or nearly so, as yttrium, but requiring admixture with a calcium 
compound to bring out its phosphorescent properties. 
113. Next I had to ascertain if the calcium could be replaced by any analogous 
body. In this case, therefore, the x was kept constant whilst the calcium was 
replaced. An ammonia precipitate (109) from a rich accumulation of orange band 
substance was chosen as the x. Tested in the usual manner, by itself, it showed 
nothing, but mixed with lime it gave the orange-band spectrum very bright and pure. 
The metals used to mix with it were in the form of sulphates—strontium, barium, 
glucinum, zirconium, thorium, magnesium, zinc, cadmium, lead, copper, silver, cerium, 
lanthanum, didymium, aluminium, manganese, tin, bismuth, antimony ; also silicic, 
titanic, tantalic, tungstic, molybdic, and niobic acids. More than half of these bodies 
possessed the property of conferring “ orange-band ” phosphorescence on the precipi tate 
under examination, although by themselves they evinced no power of giving a 
phosphorescent spectrum. 
Explanation of foregoing Anomalies. 
114. In this manner the remarkable fact was established, that the x I sought was 
an earth which of itself could give little or no phosphorescent spectrum in the radiant 
matter tube, but became immediately endowed with this property by admixture with 
some other substance, which substance likewise by itself had no power of phos¬ 
phorescing with a discontinuous spectrum. 
Of the great number of bodies used to mix with the earth x in these experiments, 
which acted best ? It was not easy to try comparative experimeuts at this early 
stage ; ultimately I came to the conclusion that lime, if not the best, was as good as 
any. 
115. These results afford a full explanation of the anomalies which had so long 
hampered my endeavours to repeat on a large scale experiments which, when working 
with small quantities, had given good results (99, 101, 108). The preliminary 
experiments were intended to ascertain whether the desired orange band was present 
or not. Natural impatience led to hurried operations and defective washing of 
precipitates, and thus some of the necessary lime was left with the phosphorescing 
body. The subsequent larger operations were performed in a more systematic manner 
with the object of securing as large a yield of substance as possible. 1 he precipitates 
were thoroughly washed, the lime was more completely thrown out, and the sought- 
for earth, although obtained, refused to reveal itself by the spectroscope and radiant 
matter tube. 
4 x 
MDCCCLXXXV. 
