Dr Pearson of London, in his very valuable paper, published in the Philosophical Transactions of 1813, on the coaly matter in the bronchial glands, was convinced beyond a doubt, that it was of foreign origin, and possessed the properties of carbon conveyed into the lungs from without. He, at that period, was not in possession of such facts as have been recently elicited on the subject of deleterious inhalation; but the very interesting materials which he brought to bear on his argument, have, I think, most satisfactorily proved the assertion which he makes, that "the lymphatics of the lungs absorb a variety of substances, especially this coaly matter, which they convey to the bronchial glands, and thus render them of a black or dark-blue colour." "The texture and proportion of the tinging matter of the glands was," he says, "different in different subjects, whether the lungs to which they belonged were in a healthy or diseased condition. In persons, from about 18 to 20 years of age, some of the bronchial glands contained no tinging black matter at all, but were of a reddish colour; others were streaked or partially black." Again, he says, "I think the charcoal in the pulmonary organs is introduced with the air in breathing. In the air it is suspended in invisible small particles, derived from the burning of coal, wood, and other inflammable materials in common life. It is admitted that the oxygen of atmospherical air passes through the pulmonary air-vesicles or cells into the system of blood-vessels, and it is not improbable, that through the same channel various matters contained in the air may be introduced. But it is highly reasonable to suppose, that the particles of charcoal should be retained in the minutest ramifications of the air-tubes, or even in the air-vesicles under various circumstances, to produce the coloured appearances on the surface, and in the substance of the lungs, as above described."
"When I compare the black lines and black net-like figures, many of them pentagonal, on the surface of the lungs, with the plates of the lymphatic vessels by Cruikshank, Mascagni, and Fyffe, I found an exact resemblance."
Dr Pearson, after various chemical experiments upon the bronchial glands with caustic potash, muriatic and nitric acid, says, "I conceive I am entitled to declare the black matter obtained from the bronchial glands, and from the lungs, to be animal-charcoal in the uncombined state, i.e. not existing as a constituent ingredient of organized animal solids or fluids." Dr Graham of London, in his paper on this subject, recorded in the 42d vol. of the Edinburgh Medical and Surgical Journal, gives the following opinion, as the result of a series of investigations, with the view of determining the nature of the disease in question. He says, I have had several opportunities of substantiating the carbonaceous matter in a state of extraordinary accumulation in black lungs supplied by my medical friends. The black powder, as derived from the lungs, (after an analysis,) is unquestionably charcoal, and the gaseous products from heated air, result from a little water and nitric acid being retained persistently by the charcoal, notwithstanding the repeated washing, but which re-acting on the charcoal at a high temperature, coming off in a state of decomposition. In regard to another analysis of a lung, he says, "The carbonaceous matter of the lung cannot therefore be supposed to be coal, altered by the different chemical processes to which it has been submitted in separating it from the animal matter. The carbonaceous matter of this lung, appears rather to be lamp black."
From the whole results, I am disposed to draw the following conclusions:—
1st, The black matter found in the lungs is not a secretion, but comes from without. The pigmentum nigrum of the ox I find to lose its colour entirely, and to leave only a quantity of white flocks, when rubbed in a mortar with chlorine water. Sepia, which is a preparation of the dark-coloured liquor of the cuttle fish, was also bleached by chlorine, but the black matter of the lungs was not destroyed or bleached in the slightest degree by chlorine, it even survived unimpaired the destruction of the lungs by putrefaction in air.
2d, This foreign matter probably varies in composition in different lungs, but in the cases actually examined, it seems to be little else than lamp black or soot.
It does not appear, as far as I can ascertain, that any of the Continental physiologists are familiar with the disease now under our consideration. Several of them, both ancient and modern, discovered black matter in the pulmonary tissues, but not connected with nor exhibiting the black phthisis. It is therefore unnecessary to refer to them in general.
The following foreign authors entertain various opinions in regard to the dark appearances in the pulmonary tissue:—
Bichat supposes the black matter in the lungs "to be owing to small bronchial glands extending along the surface of the pleura." Breschet believes that it is formed by the blood exhaled into the cellular tissue, stating that its chemical composition leads him to that conclusion. Trousseau says that it is produced by a misdirection of the natural pigments of the body, resulting from age, climate, or disease. Andral says, that the black appearances are the result of secretion, and that it is more manifest as the individual advances in life. Heasinger's opinion is, that it is analogous to pigment, and therefore he agrees with Trousseau. Lænnec was doubtful as to the real origin of black pulmonary matter. He makes a distinction between melanotic and pulmonary matter. He found that the melanotic matter was composed almost entirely of albumen, while the black pulmonary matter found in the bronchial glands contains a great quantity of carbon and hydrogen, and also that these colouring matters have other distinguishing characters. The melanotic matter is easily effaced by washing, while the other is removed with difficulty. Lænnec further says, that he suspected that this pulmonary matter might arise, at least in part, from the smoke of lamps, and other combustible bodies which are used for heat and light; for some old men are to be met with whose lungs contain very little black matter, and whose bronchial glands are but partially tinged with this colour; and it has struck him that he observed this amongst villagers who had never been accustomed to watch.[23]
Mons. Guillot, physician to the hospital for the aged at Paris, has undertaken a series of researches in regard to the black matter found in the lungs of old men of very considerable age. These investigations are published in the January, February, and March numbers of the Archives Générales de Médecine.[24] It is his belief that death in such cases is owing, in all appearance, more or less to a suppression of the circulation of air and blood by the black substance. His impression is, "that the carbon is not procured from without, but naturally deposited, as life advances, in the substance of the respiratory organs; and that this deposit of carbon causes death, by rendering the lungs irrespirable, while, at the same time, it has much influence in modifying the progress of tubercular disease; so that, if the tubercular affection was not cured, its progress was so far checked, that life has been very long preserved." The black matter envelopes completely both the pulmonary tubercles which have undergone a transformation, and the caverns which no longer contain tuberculous matter. He, while regarding these as the results of black matter in the lungs, throws no light on the cause of the deposit of the particles of carbon within the lungs.