r
elements. It would never be suspected, for example, that the reddish,
earthy-looking iron ore contains iron.

~Names of elements.~ The names given to the elements have been selected in
a great many different ways. (1) Some names are very old and their
original meaning is obscure. Such names are iron, gold, and copper. (2)
Many names indicate some striking physical property of the element. The
name bromine, for example, is derived from a Greek word meaning a
stench, referring to the extremely unpleasant odor of the substance. The
name iodine comes from a word meaning violet, alluding to the beautiful
color of iodine vapor. (3) Some names indicate prominent chemical
properties of the elements. Thus, nitrogen means the producer of niter,
nitrogen being a constituent of niter or saltpeter. Hydrogen means water
former, signifying its presence in water. Argon means lazy or inert, the
element being so named because of its inactivity. (4) Other elements are
named from countries or localities, as germanium and scandium.

~Symbols.~ In indicating the elements found in compounds it is
inconvenient to use such long names, and hence chemists have adopted a
system of abbreviations. These abbreviations are known as _symbols_,
each element having a distinctive symbol. (1) Sometimes the initial
letter of the name will suffice to indicate the element. Thus I stands
for iodine, C for carbon. (2) Usually it is necessary to add some other
characteristic letter to the symbol, since several names may begin with
the same letter. Thus C stands for carbon, Cl for chlorine, Cd for
cadmium, Ce for cerium, Cb for columbium. (3) Sometimes the symbol is an
abbreviation of the old Latin name. In this way Fe (ferrum) indicates
iron, Cu (cuprum), copper, Au (aurum), gold. The symbols are included in
the list of elements given in the Appendix. They will become familiar
through constant use.

~Chemical affinity the cause of chemical combination.~ The agency which
causes substances to combine and which holds them together when combined
is called _chemical affinity_. The experiments described in this
chapter, however, show that heat is often necessary to bring about
chemical action. The distinction between the cause producing chemical
action and the circumstances favoring it must be clearly made. Chemical
affinity is always the cause of chemical union. Many agencies may make
it possible for chemical affinity to act by overcoming circumstances
which sta