(C20H24N2O2)2 Tonic; gr. v Syrup of Iron, Quinine, and

PART IV.

ORGANIC SUBSTANCES.

INTRODUCTORY.

THE view formerly held by chemists, that vegetable and animal substances owed their peculiar chemical and physical properties exclusively to the mysterious action of life, was seriously affected by the labors of such chemists as Wöhler, in 1828, and Kolbe and Frankland, in 1847, who succeeded in producing synthetically a number of compounds from mineral substances. These so-called artificial bodies were proved to be identical in chemical composition and physical properties with those obtained from nature, and the subsequent discovery of many others has necessitated a change in the definition of the term organic chemistry. This no longer means the study of substances produced through living organisms, but, as all organic bodies have been found upon analysis to contain carbon (generally associated with hydrogen, and often with oxygen and nitrogen), the following modern definition must be accepted: Organic chemistry is the science which treats of the carbon compounds.

The plan of this work will not admit of the acceptance of the latest systems of classification which have been advanced, for, notwithstanding the ingenious skill which is clearly perceptible in many of the groupings, they are not well adapted for the study of the carbon compounds from a pharmaceutical point of view. The groups which are characterized in modern organic chemistry as alcohols, ethers, compound ethers, aldehyds, ketones, amines, and amides, necessarily bring together many substances used in the materia medica which possess few pharmaceutical or medical analogies. For instance, glycerin, mannit, and carbolic acid are properly regarded as alcohols, and they would have to be grouped together, notwithstanding their physical dissimilarities. The same classification would compel the consideration of such an incongruous pharmaceutical group as spirit of nitrous ether, stearin, and beeswax under the head of compound ethers.

It must not be understood that the present methods of grouping the carbon atoms is not of great value in studying chemistry from a purely chemical stand-point. Indeed, with the enormous advances which have been made in theoretical chemistry within the last half-century, it would be impossible to reject the results upon which the present system of classification rests.