Theory of Circulation by Respiration - Synopsis of its Principles and History

Synopsis

First step in the discovery—Animal Heat the product of Respiration. Second step—Heat evolved in the lungs by Respiration there produces Expansion. Third step—Expansion; implied motion, which from the organism must conduct the blood to the left ventricle of the Heart. Theory imperfect, until the formation of sufficient vapor or steam in the lungs is perceived and acknowledged.

The first step in the theory occurred to my mind in the winter of 1822, and while I was engaged in founding the Troy Female Seminary. Being in attendance on a course of lectures on chemistry, and at the same time teaching to a class Mrs. Marcett’s excellent work on that subject, one cold morning, as I was walking briskly up a hill, I said to myself, Why do I grow warm? Whence comes this accession of caloric? It cannot be transmitted to me from any object without, because every thing which comes in contact with  me is cold. Snow is under my feet, and frosty air surrounds me; and, as to clothing, even the softest furs impart no warmth—they but keep from escaping that which comes from within. What other method besides transmission is there of gaining heat? There is the elimination of caloric, when, in substances chemically combining, weight is gained and bulk is lost. Is there any such combination going on in me? Yes; this atmospheric air, when I inspire it, has oxygen combined with nitrogen; but when I expire, the oxygen has disappeared, and heavier substances—carbonic acid gas and watery vapor—are returned in its place. Thus, it must be, animal heat is evolved. It is the product of respiration; and it is because I breathe faster and deeper, that more carbon is oxidized or burned, and more heat is set free in my lungs; and therefore I grow warm as I walk up this hill, though all around me is cold.

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