237. Mendeleev... objected strongly to the
employment of graphic methods of expressing the Periodic
Law, on the ground that such methods did not indicate the
existence of a limited and definite number of elements in each
239. The Periodic Table, as laid down by Mendeleeff in his
writings, exhibits a symmetry which was one of its greatest
assets. For some psychological reason, symmetry has an
attraction for the human mind; and we are always apt to
prefer a regular arrangement to one in which irregularities pre-
dominate. Psychological peculiarities are, however, undesirable
guides in the search for truth; and a careful examination of
the Table in the light of our present knowledge will suffice to
show that it can boast of no such symmetry as we are led to
expect from the text-books of our student days.
For example, owing to the omission of some of the rare
earth elements and by the insertion of blanks, the Table in its
original form attained a very high degree of regularity; but
since there are, as we know from the X-ray spectra results,
only sixteen elements to fill the eighteen vacant spaces in the
Table, it is evident that the symmetry of Mendeleeff s system
is purely factitious.
Further, in order to produce the appearance of symmetry,
Mendeleeff was forced to place copper, silver, and gold in the
first group, although there is no known oxide Au2O and the
stable chloride of gold is AuCl3.
These examples are well-known, and are mentioned here
only for the purpose of enforcing the statement that the
symmetry of Mendeleef's system cannot be sustained at the
present day. Fascinating though its cut-and-dried regularity
may be, we cannot afford to let symmetry dominate our minds
when in actual fact there is no symmetry to be found.
240. The most superficial examination shows that, instead of
being a symmetrical whole, the Table is really pieced together
from a series of discrete sections.
250. The first attempt to arrange all the elements in a periodic
grouping took the form of a three-dimensional model the
Telluric Helix of de Chancourtois and it is not surprising
that from time to time attempts have been made to utilize the
third dimension as an aid to classification. It cannot be said
that much light has been thrown on the matter by these
essays; but some account of them must be given here for the
sake of completeness.
251. The main drawback to the spiral representation appears to
be that in it no new facts are brought to light, and there is no
fresh collocation of the allied elements which might give it an
advantage over the ordinary forms of classification. Also, in
most cases it is more difficult to grasp as a whole.
253 ...if we have to choose between
factitious symmetry and actual correlation of facts, we must
decide in favour of the latter, discomforting though the choice
255. The following new grouping seems worth considering.
Although it has many good points, it is not to be regarded as
a final solution, but is put forward mainly in the hope that an
examination of it may suggest some more perfect system.