14 Recent Developments of Chemical Science. [January, 
Huggins are especially connected — seemed to show the be- 
haviour of certain elementary bodies at temperatures prodi- 
giously higher than any which we can produce in our 
laboratories. But here, again, though the investigation has 
not been brought to a definite conclusion, the verdidt of the 
most judicious chemists and physicists is, so far, “ Not 
proven.” Prof. Sir H. E. Roscoe, in his opening address at 
the meeting of the Chemical Section of the British Associa- 
tion at Montreal, does not refer to the decomposition of any 
of the elements as a subject within the present scope of 
practical research. 
In proof of the difficulty of deciding such a question by 
spedtroscopic research alone, Prof. Liveing stated at the 
Montreal meeting that cadmium, mercury, and zinc, as well 
as aluminium and tin, give no spedtra at all at sufficiently 
high temperatures. Iron, on the other hand, shows so 
many lines that it either must have a very complex consti- 
tution or else it is really formed of a number of elements 
having nearly identical atomic weights, and which, so far, 
defy separation. 
We are therefore driven back to what may be called the 
indirect evidence for the compound nature of the elements. 
Under this head we gave, in 1877, an exposition of the 
“periodic theory” of Mendelejeff and Lothar Meyer, or 
rather, we should say, of Newlands. The natural relations 
of the elements thus brought to light are scarcely conceiv- 
able if these bodies are initially distindt, independent entities, 
but are quite compatible with the supposition that they have 
been evolved from some common principle. 
Now the evidence in favour of the “ periodic law ” has 
been of late materially strengthened. It is more and more 
found to lend itself to the rational interpretation of new 
classes of phenomena. One of its most interesting appli- 
cations has recently been made by Prof. T. Carnelly to the 
state in, which the elements occur in Nature. This chemist 
refers, in the outset of his memoir (“ Berichte der Deutschen 
Chemischen Gesellschaft,” vol. xvii., p. 2287), to three fadts 
laid down by Mendelejeff in his first paper on the Periodic 
Law (“ Annalen der Chemie und Pharmacie, ’’Supplement 8). 
These three fadts are — 
a. That although all elements belonging to the same 
group evince close natural relations, yet the elements 
of the even series are more nearly connedted with 
each other than with those of the odd series, whilst 
in like manner the elements of the odd series are 
