An essay on the remote and proximate causes of phthisis pulmonalis / by Andrew Hamersley.

  • Hamersley, Andrew.
Date:
1825
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Licence: Public Domain Mark

Credit: An essay on the remote and proximate causes of phthisis pulmonalis / by Andrew Hamersley. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    oxygenous portion : this is diminished, and water, in the state of vapour, with carbonic acid gas, are substituted. The necessity of a supply of fresh air in respiration must have been known from the earliest periods, but the source of this necessity was little understood, till Boyle found the re- spired air loaded with aqueous vapour, and diminished in bulk. Mayow, whose fair fame has lately been rescued from oblivion, showed that some principle, which he called a vola- tile etherial spirit, was imbibed from the air, and Dr. Black found that air respired contained carbonic acid gas. In this idea of the subject, the unfitness of the air for the continuance of life was attributed to its diminished elasticity, for it was only suspected that carbonic acid gas was not fit for the con- tinuance of this function. At last, after a period of more than twenty years, the constitution of the atmosphere was taught by Scheele and Lavoisier. They found that the apparently homogeneous atmosphere was composed of two gases of dif- ferent properties, the oxygenous and the azotic, in the pro- portion, if bulk be considered, of 22 to 78, if the weight, 26 to 74. This proportion of a fluid unfit for respiration, in air essentially necessary to life, was astonishing, till it was found that oxygen, like ardent spirits, was poisonous, by its destroy- ing, from excessive stimulus, the excitability, and that, like it, to be innocuous, it must be lowered, (diluted.) Late experi- ments, however, seems to show that the azote is not wholly useless. In explaining the process of animalization, we found the necessity of some principle, which could reduce the new- ly absorbed nutriment to an animal nature, and this appears to be azote. Yet the idea is encumbered with difficulties. Azote is an excrementitious fluid ; and the changes produced in the blood, from its circulation through the lungs, are appa- rently those from oxygen only. It is not, however, a very absurd idea that a principle at first necessary, may in the end be injurious from excess. In fact, Mr. Davy, in some very accurate experiments, found a remarkable deficiency of azote, amounting, in twenty-four hours, to about four ounces and a half.* Prepared by the foregoing statements, we feel more ready to enter into the necessary considerations appertaining to our subject.f * For the foregoing summary, the writer is indebted to article Respira- tion. Parr's Med. Diction. f In the body of our essay, as will be observed, we had incautiously ne- glected to refer to those more recent observations and experiments on the chemical changes effected by respiration, which are principally based on