Chemistry and Physics. 65 
pose a plate of cobalt blue glass to cut off the more brilliant 
portion of the spectrum. If the eyepiece is not inclined, the 
ent our observin 
ae be seen, but the fiuorescent ate! then 4% ars very 
clearly, of a uniform tint traversed ark lines. ‘These lines 
may be brought to coincide with the ies drawn on the glass and 
their deviation measured. 
With uranium glass the fluorescent spectrum is well seen from 
G ; it is very intense near H; the four rays © are also visible, 
but beyond that, little can be seen. 
With bisulphate of quinine, the spectrum is very beautiful ae 
bright. It extends but little into the visible part, about to A. 
We see very clearly the rays as far as JV, and even a little beyond. 
Esculine appears to give the most brilliant spectrum; we dis- 
tinguish very clearly the lines VV, and even 0. Re spectrum 
extends into the violet, a little bey rond that of quini 
een, ene (Magdala) gives good results for the sncrttdaee 
portion as far ; but the appearance of the ponies in oom 
is curious in the jess refrangible portions. From n to a 
No. ears all the rays with perfect clearness. = Bit, meee 
0. 196, p. 
a date streak appears in the apekoe; which may be sade to fall 
on any desired Fraunhofer line — changing the angle of incidence 
and the azimuth of the analyzer. The differe nee of phase and ratio 
of the amplitudes of the components polarized parallel ian perpen- 
dicular to the plane of reflection, or the intensity of the compo- 
nents of the reflected light, can thence be calculated for any angle 
of incidence. The most perfect surfaces are possessed by nickel, 
silver, gold and selenium; the latter being melted iad press 
with a cold plate of glass. With the exception of gold, in the 
case of all the metals here mentioned, the prime angle of incidence 
‘ion angle) diminishes wi ith the diminution of the wave- 
uR. Scr.— oe ERIES, Vou. VIL, No. 43.—JuLy, 1874. 
