486 Scientific Intelligence. 
ose we must put in the place of the flame apparatus one of the 
forked tubes and connect this with the ear by means of an india 
rubber tube. 
2. On the light emitted by the phosphorescent compounds of 
uranium.—BEcQuEREL has examined the phosphorescence spectra 
of some of the compounds of uranium, and has arrived at the 
following results: : 
(1.) The compounds of protoxide of uranium hitherto studied 
‘chloride and sulphate) did not exhibit any appreciable phospho- 
rescence. But although some compounds of the sesquioxide are 
equally inactive, this is not the case with the greater number, 
which when properly treated give rise to a more or less vivid 
emission of light. 
(2.) The greater number of these phosphorescent substances give 
a series of groups of luminous and dark bands which appear in a 
art of the spectrum extending from about C to beyond but near 
. These groups are 5, 6 or 7 in number, and the bright and dark 
bands formed by them are not in the same places for the different 
compounds, but preserve the same positions in the case of the same 
substance. 
(3.) If the succession of luminous groups in the spectrum charac- 
terizes in general the compounds of uranium, the acid in the com- 
pound determines the disposition of the bright and dark bands of 
each group, which disposition may differ greatly for the different 
compounds, 
.) In the double salts of the same class, in the sulphates and 
double sulphates for instance, the composition of each group 
remains the same, but the index of refraction of the corresponding * 
sulphates, 
__ (5.) If we consider the characteristic lines or bands of each hada 
in the same compound (which may be the center of a bright ban 
or a dark line), we find that from the first group to the seventh, 
differences between the wave-lengths of the corresponding luminous 
rays diminishes; the ratio of these differences to the mean WaV 
lengths also diminishes. i 
. 
