EDITORIAL OBSERVATIONS. 
585 
London clay, from the sand above the chalk, and from the 
chalk, have also been submitted by A. and F. Dupre to this 
method of analysis, and in all cases lithium and strontium 
v * 
were detected by them. 
It was the discovery of csesium which gave at once such 
popularity to this mode of analysis, since which Professor 
Bunsen has announced the existence of a fifth metal 
belonging to the same group, called by him rubidium, and 
found, he says, in Durkheim, Kreusnach, and other mineral 
springs, in small, but in lepidolite in larger, quantities. Both 
these metals have a chemical similarity to potassium, dif¬ 
fering, however, from it and each other in their degree of 
solubility of their double chlorides of platinum and potassium. 
This spectrum analysis ought to have been noticed by us 
before, perhaps, but there has been such a press of matter 
as to preclude its insertion. Moreover, we have been de¬ 
sirous of watching its progress, and w r e find that it gains in 
strength and importance. 
The experiments have been repeated before the members of 
the Royal Society, to their gratification. By means of it the 
presence of sodium has been detected in the atmosphere, which 
is supposed to be conveyed there by the evaporation of sea 
water in the form of chloride of sodium, and its use in the air 
has been conjectured to be that of an antiseptic. The existence 
of other metals has also been demonstrated by it, each giving 
its characteristic colour and bands to the spectrum. It has 
been averred that this exquisite mode of qualitative analysis 
can scarcely be overrated. It is founded, as already stated, 
on the power which certain substances possess of giving pe¬ 
culiar bright and coloured lines in the spectrum of a flame 
in which they are introduced, and these show themselves 
most plainly where the temperature of the flame is highest 
and its illuminating power least. By it the existence of 
certain bodies can be recognised with more certainty, greater 
quickness, and in far smaller quantities, than can be done 
by any other analytical method, and at the same time re¬ 
gardless of the nature of the substance with which the 
metals are combined. The authors say, “ In spectrum ana¬ 
lysis the coloured bands are unaffected by any alteration of 
