Outlines of chemico-hygiene and medicine, or the application of chemical results to the preservation of health, and cure of disease / by A. Dallas.

  • Dallas, A. (Angus)
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of chemico-hygiene and medicine, or the application of chemical results to the preservation of health, and cure of disease / by A. Dallas. 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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    Terence, between it and the product of the above statement, besides the proportions of each compound which they have included, lies in the different forms of the compounds found in the urine of the lower animals. As, in either case, the product is reducible to carbonic acid and ammonia exclusively, it does not signify what proportions we assume or comprehend in our calculations. The object aimed at, being simply to show, that the ultimate principal compounds are, in this case, carbonic acid and ammonia. In the vegetable kingdom, the sources and modes of admission of carbon and nitrogen, are the same in all plants. The carbon enters by the leaves, as carbonic acid; and the nitrogen, by the roots, in the form of ammonia. They are, both, the products of the decom- position of vegetable and animal bodies. They formed, previously, the constituents of living organs; but afterwards, during decay and decomposition, they return to the air and to the soil, to become again, in a new generation, constituents of similar living organs. The carbon performs a circuit. From the air, as carbonic acid, we trace it to the organism of the living plant; then to the decayed plant, combining with oxygen; and finally, to the air again, as carbonic acid. The nitrogen, likewise, we find, existing, as ammonia, in the atmosphere ; next, in the soil, having descended, with rain and snow; then in the cereals and fruits; afterwards in decayed cereals and fruits, combining with hydrogen to form ammo- nia ; and lastly, as ammonia, existing again in the atmosphere. Now throughout all their combining and decomposing processes, whether in the air, in the soil, in the living or decayed plant, the proportions in which carbon and oxygen form carbonic acid, and nitrogen and hydrogen form ammonia, are the same and invariable. All other compounds of vegetable substances, hold their constituents also, in definite and invariable quantities. When these compounds are chemically separated, the determinate quantity of each separated class of elements, is exactly the same as existed in the compound. And notwithstanding that in the compound forms, the elemental distinctions seem to be lost, such is not the case; for by analysis, the proportions of the elements are identical with those brought together, in the first instance, to form the compound. In the case of more varied compounds, the chemist obtains the same result, as in the minor one of carbonic acid. One atom of carbon and two of oxygen, brought together, form carbonic acid. Then, by analysis, the carbonic acid is separated, into one atom of carbon and two of oxygen. The quantifies of the elements separated, are equal to