show how such a
diseased state of the pulmonary organs, as has been described, should
produce such results, by impeding the necessary chemical change of the
blood. Imperfect oxygenation of the blood, consequent on the altered
pulmonary structure, must cause a general depression of all the vital
organs. The excess of excrementitious matter in the circulation, must
produce effusion of serum into the various cavities, and also into the
cellular structure; and the appearances exhibited on the surface of the
brain and its membranes, afford a full explanation of the sluggish
inanimate condition of all the sufferers towards the close of their
existence.

From the cases above reported, it must be evident, that black phthisis
is the result of foreign matter inhaled and retained within the
pulmonary structure.

It is a melancholy fact connected with mining occupations in the
locality described, that few or none who engage in it, escape this
remarkable disease. I have never known one collier in many hundreds,
who, even in his usual health, was not, as he expressed it, more or less
"touched in his breathing;" and after much experience in auscultation in
such pulmonary affections, I am the more convinced that the dyspnoea
from which they suffer, arises from impaction of the minute bronchial
ramifications induced during their labour below ground, surrounded by an
impure atmosphere. The East Lothian colliers, of all miners throughout
the kingdom, are certainly most subject to this disease; and those at
Pencaitland are so to a fearful extent. In the late inquiry for the
Parliamentary report, such has been manifestly brought out, and I am
quite able to corroborate the conclusions at which the commissioners
have arrived. It has been supposed by many that this carbonaceous
affection was caused by inhalation of coal-dust. Now, when it can be
proved, that there is as much coal-dust at one coal-work as at another,
the question comes to be, why should colliers, labouring at one
coal-work, be subject to the disease; while those engaged at another,
escape? For instance, there is as much coal-dust at Penston and Huntlaw,
where there has never been black spit, as there is at Pencaitland,
Preston-Hall, and Blindwells. I conclude, therefore, that this cannot be
the cause, otherwise they should all be liable to the disease. Again,
those who labour as coal-bankers at the mouth of the shaft, are obliged
to inhale much coal-dust in shovelling and ar