2g o The Chemistry of the Future . [July, 
of a machine, or the parts of a dissected puzzle, definite in 
their number and purpose, and all necessary to a given 
result ? Or are they a mere fragmentary and accidental 
group of objects with which we build our Lagerungs formel, 
just as children construdt their sand forts and shell grottoes 
on the shore? What would be the impression of a man of 
inquiring mind if for the first time made acquainted with 
the so-called elements and their leading properties ? He 
would see a list of some sixty bodies, from which, he is told, 
all things visible or tangible— all matter, in short — are com- 
pounded. But why their number should be between 60 and 
70, rather than between 30 and 35 or between 160 and 170, 
no reason is given or even conjedtured. Some of them, he 
is informed, — such as oxygen, hydrogen, nitrogen, silicon, 
aluminium, and sulphur, — are exceedingly abundant. 
Others, on the contrary, — as vanadium, thallium, indium, 
caesium, and gallium, occur only in minute traces. Some 
are widely distributed, and others concentrated in compara- 
tively few localities. Turning to their properties he finds 
equal difficulties. Here he will see a number of “ elements ” 
identical, or at least closely approaching, in their atomic 
weights. There, on the contrary, he finds wide gaps. Thus 
betweeen cerium (140) and erbium (178) there intervenes 
not an element. A smaller blank is found between bismuth 
(208) and thorium (231), between tungsten (184) and os- 
mium (195), between zinc (65) and arsenic (75) ; whilst, on 
the contrary, between 86 and 96 we number six elements, 
and between 195 and 200 five (see Table I.). These gaps 
may, indeed, be possibly filled up by the discovery of some 
rare element, but there is also the possibility that new dis- 
coveries may fall in the more thickly-filled parts of the series. 
With those properties of the elements which cannot as yet 
be. exhibited in a numerical series the case is very similar. 
There are groups showing a close approximation in their 
characters and behaviour. There are elements which stand 
comparatively isolated. 
How are all these faCts to be explained on the theory of 
elements primordially distinct ? Popular opinion, here as 
elsewhere, takes refuge in teleology. The elements in their 
respective proportions and in their distribution exist, as we 
find them, for the sake of man’s convenience. We demur 
to this hypothesis. Look at sulphur ; where existing in 
quantity the very key with which we unlock the treasure- 
house of Nature — no less essential to the chemical technolo- 
gist than is iron to the engineer; but where occurring in 
small quantities, what a source of evil ! Take the case of 
