Human physiology, statical and dynamical, or, The conditions and course of the life of man / by John William Draper.

Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: Human physiology, statical and dynamical, or, The conditions and course of the life of man / by John William Draper. 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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    ganic systems, whether vegetable or animal, whether humble or elaborate- An animal ere- ]y developed, possess no power of creating material. Their but;3only trans- function is of necessity limited to the mere transformation of sta'ce^t eUb su^s^ances furnished to them. From this it follows, even in ceives. the case of man, that the substances dismissed from the sys- tem are metamorphosed forms of those which have been received, and that, whatever their appearance may be, they must have arisen from the reaction of the food, water, and air upon one another. This reaction we may proceed to view as a purely chemical result: for, casting aside all the vain hypotheses of the older physiology, and per- mitting ourselves to be guided by the harmonies of nature, we should ex- pect to recognize in the changes taking place in organic systems, and in the phenomena which attend those changes, the same results which arise in the artificial or experimental reaction of food, water, and air on each other. A very superficial examination of the facts shows at once the The chemical correctness of this expectation. On such an examination we matters re °f now enfer’ premising it with some general remarks needful for ceived. our purpose on the nature and properties of food, water, and air. 1st. Of Food.—-No article is.suitable for food except it be of a com- bustible nature. Its chemical constitution must be such that if its tem- perature be raised to a proper degree with a due access of atmospheric air it will take fire and burn, and the products of its combustion must be car- bonic acid gas and water, or those substances with nitrogen or its com- pounds. 2d. Of Water.—This may be taken as the type and representative of all the various liquids used as drinks. It evaporates at any tempera- ture, even at those which are lower than its freezing point, and in tins evaporation produces cold. Water vaporizing from the skin absorbs 1114 degrees of heat, and hence exerts a most powerful refrigerating action. Over saline substances there are few bodies which exercise so general a solvent effect. In virtue of this property, it is enabled to introduce in the dissolved state such compounds as are wanted for the nutrition of the system, and in the same manner to carry away the wasted products of decay. 3d. Of Atmospheric Air.—The active principle of the air is oxygen gas, the effects of which are moderated by the presence of a large quanti- ty of nitrogen—four fifths of the air consisting of this latter substance. Physiologically, we often use the terms atmospheric air and oxygen syn- onymously. The chief materials which a living being receives from the external world are, therefore, combustible matter, water, oxygen gas ; and out of the action of these upon one another all the physical phenomena of its life arise.