POPULAR SCIENCE REVIEW. 
518 
new and rare metals in Triphyline : — “ Having obtained a quantity of the 
residues of the preparation of lithia from triphyline, which gave, when 
examined in the spectrum apparatus, evidences of the presence of rubi- 
dium and caesium, I have, at the request of Professor Bunsen, made an 
analysis of it. After the removal of the iron and phosphoric acid, and 
the conversion of the sulphates of the alkalies into chlorides, it was found 
to contain : — • 
Chloride of lithium 
40-98 
?3 
potassium 
9-29 
33 
sodium 
50-04 
33 
caesium 
Oil 
3? 
rubidium 
0-18 
100-60 
“The method of estimating the rubidium and caesium depends upon the 
insolubility of the platina chlorides as compared to that of the same salt of 
potassium ; and the difference of solubility is not so great as to give very 
accurate analytical results. The above approximation, however, serves to 
show that, like some other minerals containing lithia, triphyline contains 
small quantities of these new and highly-interesting alkaline bases.” 
Fizeau has recorded a curious and somewhat paradoxical experiment 
on the light evolved by burning Sodium. Finding the simple light which 
a soda compound communicates to a flame, not of sufficient intensity for 
some researches in which an intense but perfectly homogeneous light was 
requisite, this experimenter tried the plan of burning the metal sodium in 
air, in the expectation that, as the combustion was accompanied with an 
extraordinary development of heat and light, a homogeneous light of the 
desired intensity would in this way be easily obtained. Upon trying the 
experiment, however, it was found that the light of the burning metal 
was quite different in its character to that known as the ordinary soda 
flame. The latter, when examined by spectral analysis, shows aluminous 
double line D on a dark ground ; but the former was seen to emit a 
light which in the spectroscope appeared continuous from the red to the 
violet, with the exception that the line D stood out perfectly black on 
the luminous ground. This unlooked-for phenomenon, strange as it may 
appear at first sight, is, however, in strict accordance with theory. The fact 
that the bright sodium lines can be reversed or changed to dark ones by passing 
through a layer of heated sodium vapour is well known, and forms the 
fundamental point of Ivirchhoff’s theory of the constitution of the sun. 
The simple explanation of the black lines in the above experiment appears 
therefore to be, that the sodium compounds formed by the very rapid 
combustion of the metal were carried up into the flame in the solid state, 
and heated to whiteness, when they emitted light of every degree of 
refrangibility : a layer of ignited sodium vapour being in front of this 
continuous spectrum carved out of it the black lines. 
Before we leave the subject of Artificial spectra, we may refer to a method 
lately given by Crookes, by which these can be observed in great perfection 
with very simple apparatus. The beauty and perfection of a metallic 
spectrum depends in general upon the heat of the flame. In order to bring 
