260 Scientific Intelligence. 
4. On the absorption spectrum of Didymium, Erbium and Terbium. 
—Dezarontainz, who maintains the existence of erbium and terbium 
as distinct elements, has compared the absorption spectra of these two 
by Gladstone. The absorption bands in the spectra of erbium and ter- 
bium were first observed by Bahr. The didymium spectrum has been 
also studied by Rood and by Erdmann, both of whom detected several 
ark bands not noticed by Gladstone. Erbium gives usually five lines 
or bands, and eight when in the form ofa thick syrup. Er® remains 
after all the other lines have vanished. Terbium is chara 
isti thi 
three bands of metal, of which only two are very distinct. The , 
or Tr°, is difficult to recognize, and perhaps does not belong to the metal 
at all. Upon a scale on which Na=27, Lit=10 and Ti=43, the 
author found 
Dit= 9 Tr® =30-32 Erf= 9 
FTG —=48-50 aig 
a=28-32 c= 85-89 p16 
b=48-50 h—42 
54-55 e=44 
e=66-67 a==48-50 
rene b=65 
f=73-75 c==85-90 
c=85-91 
5. 
Cristalli ed il loro ingrandimento 3 par Arcanceto Scaccui. 120, 
28 
