experiment, very refined in its nature, and very good in its results. You
will observe that the good air has done nothing to the lime-water; in the
other case nothing has come to the lime-water but my respiration, and you
see the difference in the two cases.

Let us now go a little further. What is all this process going on within
us which we cannot do without, either day or night, which is so provided
for by the Author of all things that He has arranged that it shall be
independent of all will? If we restrain our respiration, as we can to a
certain extent, we should destroy ourselves. When we are asleep, the
organs of respiration, and the parts that are associated with them, still
go on with their action--so necessary is this process of respiration to
us, this contact of the air with the lungs. I must tell you, in the
briefest possible manner, what this process is. We consume food: the food
goes through that strange set of vessels and organs within us, and is
brought into various parts of the system, into the digestive parts
especially; and alternately the portion which is so changed is carried
through our lungs by one set of vessels, while the air that we inhale and
exhale is drawn into and thrown out of the lungs by another set of
vessels, so that the air and the food come close together, separated only
by an exceedingly thin surface: the air can thus act upon the blood by
this process, producing precisely the same results in kind as we have seen
in the case of the candle. The candle combines with parts of the air,
forming carbonic acid, and evolves heat; so in the lungs there is this
curious, wonderful change taking place. The air entering, combines with
the carbon (not carbon in a free state, but, as in this case, placed ready
for action at the moment), and makes carbonic acid, and is so thrown out
into the atmosphere, and thus this singular result takes place: we may
thus look upon the food as fuel. Let me take that piece of sugar, which
will serve my purpose. It is a compound of carbon, hydrogen, and oxygen,