he atom is enormously too large compared with the
enclosures, which are absurdly too small; a scale drawing would mean an
almost invisible dot on a sheet of many yards square.

The use of the words "positive" and "negative" needs to be guarded by the
following paragraphs from the article on "Chemistry" in the _Encyclopaedia
Britannica_. We use the words in their ordinary text-book meaning, and have
not, so far, detected any characteristics whereby an element can be
declared, at sight, to be either positive or negative:--

"When binary compounds, or compounds of two elements, are decomposed by an
electric current, the two elements make their appearance at opposite poles.
These elements which are disengaged at the negative pole are termed
electro-positive or positive or basylous elements, while those disengaged
at the positive pole are termed electro-negative or negative or chlorous
elements. But the difference between these two classes of elements is one
of degree only, and they gradually merge into each other; moreover the
electric relations of elements are not absolute, but vary according to the
state of combination in which they exist, so that it is just as impossible
to divide the elements into two classes according to this property as it is
to separate them into two distinct classes of metals and non-metals."

We follow here the grouping according to external forms, and the student
should compare it with the groups marked in the lemniscate arrangement
shown in Article II (p. 377, properly p. 437, February), reading the group
by the disks that fall below each other; thus the first group is H, Cl, Br,
I (hydrogen, chlorine, bromine, iodine) and a blank for an undiscovered
element. The elements grow denser in descending order; thus hydrogen is an
invisible gas; chlorine a denser gas visible by its colour; bromine is a
liquid; iodine is a solid--all, of course, when temperature and pressure
are normal. By the lowering of temperature and the increase of pressure, an
element which is normally gaseous becomes a liquid, and then a solid.
Solid, liquid, gaseous, are three interchangeable states of matter, and an
element does not alter its constitution by changing its state. So far as a
chemical "atom" is concerned, it matters not whether it be drawn for
investigation from a solid, a liquid, or a gas; but the internal
arrangements of the "atoms" become much more complicated as they become
denser and denser, as is seen by the