ish them carefully would lead
far afield into the complexities of organic chemistry. All these animal
and vegetable products which were used as fuels for light-sources are
rich in carbon, which accounts for the light-value of their flames. The
brightness of such a flame is due to incandescent carbon particles, but
this phase of light-production is discussed in another chapter. These
oils, fats, and waxes are composed by weight of about 75 to 80 per cent.
carbon; 10 to 15 per cent. hydrogen; and 5 to 10 per cent. oxygen.

Until the middle of the eighteenth century the oil-lamps were shallow
vessels filled with animal or vegetable oil and from these reservoirs
short wicks projected. The flame was feeble and smoky and the odors were
sometimes very repugnant. Viewing such light-sources from the present
age in which light is plentiful, convenient, and free from the great
disadvantages of these early oil-lamps, it is difficult to imagine the
possibility of the present civilization emerging from that period
without being accompanied by progress in light-production. The
improvements made in the eighteenth century paved the way for greater
progress in the following century. This is the case throughout the ages,
but there are special reasons for the tremendous impetus which
light-production has experienced in the past half-century. These are the
acquirement of scientific knowledge from systematic research and the
application of this knowledge by organized development.

The first and most notable improvement in the oil-lamp was made by
Argand in 1784. Our nation was just organizing after its successful
struggle for independence at the time when the production of light as a
science was born. Argand produced the tubular wick and contributed the
greatest improvement by being the first to perform the apparently simple
act of placing a glass chimney upon the lamp. His burner consisted of
two concentric metal tubes between which the wick was located. The inner
tube was open, so that air could reach the inner surface of the wick as
well as the outer surface. The lamp chimney not only protected the flame
from drafts but also improved combustion by increasing the supply of
air. It rested upon a perforated flange below the burner. If the glass
chimney of a modern kerosene lamp be lifted, it will be noted that the
flame flickers and smokes and that it becomes steady and smokeless when
the chimney is replaced. The advantages of such a chimney