SEPTEMBER 1, 1899. ] 
Chemical Elements, p. 31): ‘(The name 
copper is used to distinguish a certain group 
of properties, that we always find associated 
together, from other groups of associated 
properties, and if we do not find the group 
of properties connoted by the term copper 
we do not find copper.”’ 
These properties are exhibited by the ac- 
tion of a small group of forces. Perhaps we 
do not know all of the forces ; certain it is 
that we do not accurately know all of the 
properties, but, to quote Patterson-Muir 
again: ‘The discovery of new properties al- 
ways associated with a group of properties 
we call copper would not invalidate the 
statement that copper is always copper.” 
The properties of an atom are either 
primary, inherent and as unchanging as the 
atom itself, or they are secondary and de- 
pendent upon the influence of the other 
atoms, or varying with the change of con- 
ditions. To the first class belong such 
properties as the atomic weight, atomic 
heat, specific gravity, etc.; to the second, 
chemical affinity, valence, etc. In all the 
study of the atom the distinction between 
these should be carefully maintained in 
order that there may be clear thinking. 
There is no field of mental activity re- 
quiring more faith than that of the chemist. 
He is dealing with the ‘ evidences of things 
unseen.’ He must not be content with the 
mere gathering of facts, but divine what he 
can of their deeper meaning. Few chem- 
ists have had such insight as Graham into 
the significance of even the simplest 
changes. He was not content with mere 
surface observation. Even the commonest 
observed phenomena were to him full of 
meaning as to the atoms and their ‘ eternal 
motion.’ Thorpe (Essays in Historical 
Chemistry, p. 219) has drawn afresh the 
attention of the chemists to the thoughtful 
words of this great thinker. His mind was 
filled with the fascinating dream of the 
unity of matter. ‘In all his work,’’ says 
SCIENCE. QUT 
Adam Smith, ‘we find him steadily thinking 
on the ultimate composition of bodies. He 
searches after it in following the molecules 
of gases when diffusing ; these he watches 
as they flow into a vacuum or into other 
gases, and observes carefully as they pass 
through tubes, noting the effect of weight, 
of composition, upon them in transpiration. 
He follows them as they enter into liquids 
and pass out, and as they are absorbed or 
dissolved by colloid bodies ; he attentively 
inquires if they are absorbed by metals in 
a similar manner, and finds remotest analo- 
gies which, by their boldness, compel one 
to stop reading and to think if they really 
be possible.” 
In his paper entitled ‘Speculative Ideas 
respecting the Constitution of Matter,’ pub- 
lished in the Proceedings of the Royal So- 
ciety in 1863, which Thorpe calls his ‘ Con- 
fession of Faith,’ he tells of his conception 
that these supposed elements of ours may 
possess one and the same ultimate or atomic 
molecule existing in different conditions of 
movement. 
It is not possible for me, in the limits of . 
this address, to array before you all of the 
various evidence which leads to the belief 
that our so-called elementary atoms are 
after all but compounds of an intimate, pe- 
culiar nature whose dissociation we have 
as yet been unable to accomplish. When 
properly marshalled, it gives a very stagger- 
ing blow to the old faith. Thorpe speaks 
of the ‘old metaphysical quibble concern- 
ing the divisibility or indivisibility of the 
atom.” To Graham “the atom meant 
something which is not divided, not some- 
thing which cannot be divided.” The 
original indivisible atom may be something 
far down in the make-up of the molecule. 
How shall the question as to the com- 
posite nature of the elements be ap- 
proached? The problem has been attacked 
from the experimental side several times 
during the last half century, but the work 
