oxygen. By uniting the nitrogen and
oxygen chemically (N_{2}O) we have nitrous oxide, laughing-gas. Ordinary
starch is made up of three different elements--six parts of carbon, ten
parts of hydrogen, and five parts of oxygen (C_{6}H_{10}O_{5}). Now if
we add water to this compound, we have a simple mixture of starch and
water, but if we bring about a chemical union with the elements of water
(hydrogen and oxygen), we have grape sugar. This sugar is formed in
green leaves by the agency of sunlight, and is the basis of all plant
and animal food, and hence one of the most important things in nature.

Carbon is a solid, and is seen in its pure state in the diamond, the
hardest body in nature and the most valued of all precious stones, but
it enters largely into all living bodies and is an important constituent
of all the food we eat. As a gas, united with the oxygen of the air,
forming carbon dioxide, it was present at the beginning of life, and
probably helped kindle the first vital spark. In the shape of wood and
coal, it now warms us and makes the wheels of our material civilization
go round. Diamond stuff, through the magic of chemistry, plays one of
the principle roles in our physical life; we eat it, and are warmed and
propelled by it, and cheered by it. Taken as carbonic acid gas into our
lungs, it poisons us; taken into our stomachs, it stimulates us;
dissolved in water, it disintegrates the rocks, eating out the carbonate
of lime which they contain. It is one of the principal actors in the
drama of organized matter.

V

We have a good illustration of the power of chemistry, and how closely
it is dogging the footsteps of life, in the many organic compounds it
has built up out of the elements, such as sugar, starch, indigo,
camphor, rubber, and so forth, all of which used to be looked upon as
impossible aside from life-processes. It is such progress as this that
leads some men of science to believe that the creation of life itself is
within the reach of chemistry. I do not believe that any occult or
transcendental principle bars the way, but that some unknown and perhaps
unknowable condition does, as mysterious and unrepeatable as that which
separates our mental life from our physical. The transmutation of the
physical into the psychical takes place, but the secret of it we do not
know. It does not seem to fall within the law of the correlation and the
conservation of energy.

Free or single atoms are very rare