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It remained so for a very long period; but it is now a considerable number of years since a distinguished foreign chemist contrived to fabricate Urea, a substance of a very complex character, which forms one of the waste products of animal structures. And of late years a number of other compounds, such as Butyric Acid, and others, have been added to the list.

In the first there is an increase above normal; in the second the volume of urea is stationary; in the third decreased, increased, or stationary. When the urea is stationary, which is most frequently the case, it is necessary to calculate the coefficient of oxidation; that is, the relation existing between the solid matters of the urine and the urea.

J.H. Gilbert, and myself, in a recent volume of the Journal of the Royal Agricultural Society of England. In the Rothamsted Laboratory, experiments have also been made on the nitrification of solutions of various substances. Besides solutions containing ammonium salts and urea, I have succeeded in nitrifying solutions of asparagine, milk, and rape cake.

The latter consist chiefly of certain nitrogenous substances known as urea and uric acid, a considerable quantity of mineral salts, and some coloring matter. Urea, the most important and most abundant constituent of urine, contains the four elements, but nitrogen forms one-half its weight. While, therefore, the lungs expel carbon dioxid chiefly, the kidneys expel nitrogen.

The elimination of these wastes is simply a problem of chemistry and mechanics. In the removal of the ash, however, we have something more, for here again we are brought up against the vital action of the cell. This ash takes chiefly the form of a compound known as urea, which finds its way into the general circulatory system. From the blood it is finally removed by the kidneys.

It remained so for a very long period; but it is now a considerable number of years since a distinguished foreign chemist contrived to fabricate Urea, a substance of a very complex character, which forms one of the waste products of animal structures. And of late years a number of other compounds, such as Butyric Acid, and others, have been added to the list.

Nay, they would not even be in the least painfully affected at witnessing the generation of animals of complex organisation by the skilful artificial arrangement of natural forces, and the production, in the future, of a fish by means analogous to those by which we now produce urea.

Researches have shown that alcohol increases the amount of uric acid in the body and decreases the amount of urea found in the urine. The conclusion to be drawn is that alcohol interferes in some way with the change of the harmful uric acid into the comparatively harmless ureaan interference which in some instances results in great harm. Wines contain acids which may also act injuriously.

To neglect this is as serious an omission for such students as for chemists would be the neglecting to determine whether it is nitrogen or hydrogen, urea or stearine, that has been extracted from a tissue, or which it is whose combinations they are studying in this or that chemical operation.

Since Wöhler’s discovery that urea could be built up by artificial combination, more and more of the carbon-compounds which were previously regarded as specialities of the vital force have been produced by artificial syntheses. The highest synthesis, that of proteids, has not yet been discovered, but perhaps that, too, may yet be achieved.