ction with this phenomenon,
viz.--Does the carbon increase in the pulmonary tissues after the
collier has relinquished the occupation of a miner, and when there can
be no further inhalation, and if so, whence comes this increase? It must
be admitted, judging from several of the cases which follow, that it
does considerably augment. From this remarkable fact, does it not appear
probable, that when carbon is once lodged in the pulmonary structure by
inhalation, there is created by it a disposing affinity for the carbon
in the blood, by which there is caused an increase in the deposit of
carbon, without any more being inhaled.

_Appearances on Dissection._ In classifying the morbid appearances
observed in the pulmonary structure, I arrange them according to
divisions corresponding to three stages of the disease. _First_, Where
there exists extensive irritation of the mucous lining of the air
passages; and the carbon being inhaled, is absorbed into the
interlobular cellular substance, and minute glandular system, thereby
impeding the necessary change upon the blood. _Secondly_, Where the
irritative process, the result of this foreign matter in the lungs, has
proceeded so far, as to produce a variety of small cysts, containing
fluid and semi-fluid carbonaceous matter, following the course of the
bronchial ramifications. _Thirdly_, Where the ulcerative process has
advanced to such an extent, as to destroy the cellular texture, and
produce extensive excavation of one or more lobes.

_Stethoscopic Signs._--In the early stages, the sounds indicate a
swollen state of the air-passages, and vary in character according to
the part examined. The whistling and chirping sounds are loud and
distinct in the large and small bronchial ramifications, and both from
the absence of expectoration and the presence of the pulmonary bruit,
the highly irritated state of the mucous linings is apparent. The
affection ultimately assumes a chronic form, and continues present in
the respirable portions of the organ during life. As the carbonaceous
impaction advances, the sounds become exceedingly dull over the whole
thoracic region, and in many of the cases no sound whatever can be
distinguished. Where the lungs are cavernous, it is very easy to
discover pectoriloquy, from the contrast to the general dulness, and
when pleuritic and pericardial effusion advance much, it is difficult to
ascertain the cardiac action.

Such is a short account of the _Cau