Volume 1
The physiological anatomy and physiology of man / by Robert Bentley Todd and William Bowman.
- Date:
- 1845-1856
Licence: Public Domain Mark
Credit: The physiological anatomy and physiology of man / by Robert Bentley Todd and William Bowman. 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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![CHEMICAL CONSTITUTION [iNTltftD. by a very high number. Respecting the mode of combination of these elements much uncertainty prevails. Some chemists consider them united equally with each other, and regard the organic prin- ciples themselves as ternary or quaternary compounds of them. Rut others have suggested a mode of combination more analogous to that of inorganic substances (see page 5) ; namely, that two or three of the elements form a compound radicle, with which the remaining one unites to form a binary compound. In a body, for example, consisting of three elements, two would form the com- pound radicle, or, in one composed of four elements, three would constitute it. This mode of composition has been rendered more probable in the secondary organic products, than in the true proxi- mate principles; and it may be illustrated by an example taken from the former class. Ether is composed of four atoms of carbon, five atoms of hydrogen, and one atom of oxygen ; the carbon and hydrogen constitute a hypothetical compound radicle, called ethyl, which is united with one atom of oxygen: so that ether is an oxide of ethyl, and its formula may be expressed C., U5 + 0. Among the secondary organic products of the vegetable class but the great majority of proximate organic elements, whether pri- ] mary or secondary, are composed of three or four essential elements, In contrasting, then, the chemical composition of organic with that of inorganic substances, we perceive, that, applying the binary ; theory to both classes of substances, their mode of combination is I strictly analogous ; there being, however, this distinction, that, ] among organic substances combination with a compound radicle is j the prevailing mode, and that the union of two simple substances is ] rare. If, on the other hand, we adopt the theory of oxy-acid-salts '■ for inorganic compounds, and view the organic principles as ternary j or quaternary compounds of simple elements, each to each, then it is evident that the most marked difference must exist between the two * classes of compounds, the latter being formed on principles entirely : dissimilar from those which regulate the composition of the former. It is probable, however, that the progress of Chemistry will shew that the binary theory is applicable to both classes of sub- stances, and that the same mode of chemical composition prevails ^ through both kingdoms of Nature. If so much uncertainty exists in reference to the manner of com- I bination of the simple elements to form organic compounds, it : is no wonder that the attempts of chemists to produce them bv ] artificial processes should have met with so little success. No one we meet a few instances of binary compounds of simple elements;](https://iiif.wellcomecollection.org/image/b28043327_0001_0030.jp2/full/800%2C/0/default.jpg)
