Licence: Public Domain Mark
Credit: Principles of forensic medicine / by William A. Guy and David Ferrier. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![twenty.fom- hours, and ia which inflation had uot been practised floated, and that imperfectly, but sank again when forcibly com- pressed.* _ This test, then, does uot distinguish imperfect respiration from imperfect inflation. On the other hand, my experiments made in the year 1841 prove that lungs completely distended by inflation cannot be made to sink by pressure short of that which destroys their texture; and that lungs so distended with air differ from those that have breathed comjDletely only by requiring somewhat more pressure to make them sink. I subjoin an account of one of these experiments from notes taken at the time :—■ I took the lungs of a child two months old who had died of marasmus, and the lungs of a foetus, still-born at eight months. I inflated the fu3tal lungs completely, and in doing so ruptured the air-cells, and produced emphysema over the entire surface, so that when I ceased to inflate them, the lungs rapidly collapsed. I then took one_ lobe from the lung of either body, and, placing them together in a cloth, submitted them, by means of an assistant, to strong pressure. Both portions still retained their buoyancy. I next stood on the cloth, and repeatedly stamped on it, but still both floated, though their structure was almost destroyed. I then took a portion from the lungs of both children, distinguishing the lung which had breathed by the darker colour of its central portiou, placed them both together in the same cloth, and pro- ceeded as before. After applying pressure by twisting the cloth strongly, both pieces continued to float; they retained their buoyancy even after they were trodden on, and it was not till they were pounded with the heel, and their structure thoroughly broken u]d, that the inflated portion sank ; the portion of the lungs which had breathed still floated, though imperfectly. On pounding this portion of lung a second time, this likewise sank. A second and a third experiment led to the same result, the inflated portion of lung sinking after a less degree of pi-essure than the portion which had breathed, but the structure being in both portions broken up before their buoyanoy was destroyed. Another series of experiments yielded the same result (Gr.). If, in these experiments, pressure short of that required to break down the structure of the lung, had caused the inflated portions to sink, while the portions that had breathed did not sink till their structure was destroyed, we could understand how 2vessure might become a means of diagnosis; but as the only difference is one of degree, and as, in any given case, we have to examine a portion of lung separately, and not side hy side with one which we can take as a standard of comparison, it is obvious that this test is not applicable to medico-legal purposes. It has been objected that these experiments, _ made on lungs inflated out of the body, do not admit of application to the case of * Schmitt, 'NcMie Vi'rsuclio,' Ac, OSixl obsprvatioii, p. 217.](https://iiif.wellcomecollection.org/image/b21965183_0120.jp2/full/800%2C/0/default.jpg)
