These, together with similar results obtained by experimenting upon other animals and birds, dispose me to infer that carbon is formed or secreted by animals out of other bodies. On a more minute examination of these experiments, we find, that when animals secrete carbon, hydrogen and oxygen disappear. This fact leads us to a knowledge of one source of animal heat; for, imperfect as our acquaintance with the specific heat of bodies may be, it is sufficient to warrant us in saying, that if

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... en and oxygen disappear, and if this chemical change has for its result carbon, l.eat will be generated. Our experiments teach us, that proportionate to the exertion of any animal, within certain limits, is carbon secreted. Hence, as every one is aware,