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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![A supporter of tlie hydrostatic test, ia this its modified form, would assert on its belialf, that if the lungs, both entire and divided, when placed in water, sink, both before and after being submitted to pressure, respiration has not taken place. The objections to this assertion are the same that apply to the earlier test—viz., disease and imperfect respiration—but with this differ- ence, that portions containing much blood and too little air to render them buoyant, might possibly float after part of the blood had been forced out, and the texture flattened. Hence the sinking of the lungs after pressure, would afford a stronger reason for supposing that respiration had not takeu place. But if the several portions of lung float, both before and after pressure; and this buoyancy be taken as a proof of respiration, do the two objections urged with success against the earlier test— viz., putrefaction and inflation—hold good against this modern test also? The objection on the score of putrefaction falls at once to the ground; for the mere 23ressure of the fingers expels the air gene- rated by putrefaction, and causes the lungs to sink. There remains, then, the single objection of inflation. That air introduced into the lungs by inflation will render them buoyant, there can be no doubt; but whether pressure will distin- guish the buoyancy due to respiration from that due to inflation is a question that demands very careful consideration. The addition of pressure to the old hydrostatic test was sug- gested by Beclard, and introduced into practice in this country by Dr. Taylor,* and Mr. Jennings.f both of whom employed it as a diagnostic mark. The former concludes from repeated experi- ments, that air, introduced by artificial inflation, may, under all circumstances, be expelled by compression, if the experiment be properly performed, and the pressure continued a sufficient length of time.;]: Mr. Jennings states, that air introduced into the lungs by artificial inflation may be expelled by pressure, so that the lungs will sink in water, and on the other hand, that after respiration the air cannot be expelled from the lungs without completely breaking down the structure of every part of the organ. Any part, however small, not thus broken down, will continue to float. This statement of Mr. Jennings respecting respired air is corrected by Dr. Taylor, on the authority of Case III. in the Essay cited.§ This case proves that air, from respiration (imperfect respiration), may, by very moderate pressure, be forced out from divided portions of the organs; while Case II. shows that there are no satisfactory means of distinguishing artificial inflation from feeble respiration. Schmitt also reports a case in which only the middle lobe of the right lung of an infant that had lived * 'Loudon Med. and Thys. Jourual,- Xov. 1832, and Jan. nnd May, 1833. t 'Trans, of Prov. Med. .and Surg. i\ssnciatiou for 1833.' X ' Guy's Ho.spital E(3])ort,s,' No. v. § Tho cliild .survived six hours, and breathed very imperfectly.](https://iiif.wellcomecollection.org/image/b21965183_0119.jp2/full/800%2C/0/default.jpg)
