at the secretory function is ever after so changed in its
character, that the gland which formerly secreted mucus, to lubricate
the passages, now performs the same service with muco-carbon, and
continues to do so during the remainder of the patient's life--even, as
I have often seen, long after he has desisted from the occupation of a
coal-miner. In fact, it constitutes a striking peculiarity of this
disease, that when the carbon is once conveyed into the cellular tissue
of the lung, that organ commences the formation of carbon, thus
increasing the amount originally deposited, as was strikingly
exemplified in the case of Duncan and others, to be afterwards detailed.
Duncan had not for fifteen years been engaged in mining operations, nor
was there any possibility of his having inhaled more carbon: yet in him
it was found to have increased to the greatest possible extent, leaving
but a small portion of useful lung.

I have been long impressed with the belief, that the carbon is contained
in considerable quantity in the blood, particularly in the blood of
those far advanced in the disease. This impression arises, not only from
its dark and inky appearance, but from its sluggish flow, and
non-stimulating effects on the heart and general system; and when we
examine the morbid condition of the pulmonary structure,--ascertain the
presence of carbon in the glandular system and minute lymphatic vessels
of the lungs, and consider the relation existing between them and the
circulating fluid, we cannot suppose it possible, that such a mass of
foreign matter should be lodged in their parenchymatous substance
without imparting a portion to the blood. I was never more struck with
this, than in the case of Duncan, where the blood was more like thick
brownish ink than vital fluid.

No one who has witnessed the economy of these pits, can doubt the
inhalation, to a great degree, of lamp and gunpowder smoke into the
pulmonary tissue. What may be its chemical action there, is a question
for us to attend to as we proceed. If it be considered an established
fact, that carbon is inhaled, possessing all the chemical qualities of
that substance found floating in the air of the coal-mine, and either
expectorated from the lungs during life, or retained in those organs
till after death, we cannot but conclude, that the black matter is the
result of an external cause, and that that cause is the sooty matter.

Another question arises here, in conne