During the past winter inflammation of the lungs has destroyed the
lives of many persons who, although they were in most cases past the
meridian of life, yet still apparently enjoyed vigorous health, and, I
have little doubt, would still have been alive and well had the
preventive means here laid down against the occurrence of the disease
from which they perished been effectively practiced at the proper
time.

The most important anatomical change occurring during the progress of
pneumonia is the solidification of a larger or smaller part of one or
both lungs by the deposit in the terminal bronchial tubes and in the
air cells of a substance by which the spongy lungs are rendered as
solid and heavy as a piece of liver. The access of the respired air to
the solidified part being totally prevented, life is inevitably
destroyed if a sufficiently large portion of the lungs be invaded.

This deposit succeeds the first or congestive stage, and it occurs
with great rapidity; an entire lobe of the lung may be rendered
perfectly solid by the exudation from the blood of fully two pounds of
solid matter in the short space of twelve hours or even less. The
rapidity with which the lungs become solidified amply accounts for the
promptly fatal results that often attend attacks of acute pneumonia.
If recovery takes place, the foreign matter by which the lung tissue
has been solidified is perfectly absorbed and the diseased portion is
found to be quite uninjured. The only natural method by which the
blood can be freed from the presence of foreign matter is by the
oxidation--the burning--of such impure matters; the results being
carbonic acid gas that escapes by the lungs and certain materials that
are eliminated chiefly by the kidneys. But when these blood impurities