It is no uncommon occurrence, in examining the pulmonary structure of those who have resided in large and smoky towns, to find both the substance of the lungs and bronchial glands containing black matter; and this is the case especially with persons who, in such situations, have passed the prime of life. But few, though not living in crowded towns, have not, at some period of their life, come in contact with smoke, and been obliged to breathe it, minutely combined with the air. It is not, therefore, to be supposed improbable, that a portion of the infinitely small particles, thus suspended in the atmosphere, should effect a settlement in the more minute air-cells, and in course of time, be conveyed to the interlobular cellular tissue by the process of absorption, and thence to the bronchial glands. There are several cases on record, from amongst iron-moulders,[20] where the pulmonary structure has been found heavily charged with carbonaceous matter, from the inhalation of the charcoal used in their processes, and where, during life, there was a free black expectoration.[21] There is, then, little doubt that the bronchial glands, from their appearance in miners, moulders, and others, are the recipients of a portion of impurities which have been carried into the pulmonary structure by inhalation, and also those left after the process of oxygenation of the blood; and when it is fully ascertained, from the character of the atmosphere in the coal mine, that deleterious matter in this form must be conveyed to the air-cells during respiration, there is little difficulty in coming to the conclusion, that the black fluid found to such an extent in these glands in the collier and moulder, is similar to, and a part of, that discovered infiltrated into the substance of the lungs. If we trace the black matter in the lymphatic vessels, (which has been done), from the pulmonary organs to the bronchial, mediastinal, and thoracic glands, and from thence to the thoracic duct, we cannot but admit, that it does find its way into the venous system, and thereby contaminates the vital current.[22]