Finally, I had the idea of trying an experiment with regard to propylamine upon my own urine, which I made after a {283} supper consisting of roast veal, potato-salad, and a glass of water, and which was neither acid nor alkaline. I poured three ounces of the urine, fresh made and still quite warm, upon four ounces of burned lime, and submitted it to distillation. The distilled product had indeed the odor of pure propylamine, and re-acted strongly alkaline; but acted in a remarkable manner on tincture of iodine in the same way as liquid ammonia. After having neutralized it with sulphuric acid, the liquid showed when tested with tannic acid and nitrate of silver, an unmistakable proportion of propylamine. Might this be formed out of the urea? My experiment confirms, at all events, the opinion stated above; the beginning is made, and I may now pass from experiment to scientific deductions.
Remarks by Dr. Buchner:—My friend, Dr. Winckler, in communicating the above paper, very agreeably surprised me by transmitting at the same time specimens of his preparation of propylamine, and that too in quantities varying from one to two drachms, for which I hereby beg to express to him publicly my best thanks. I received from him, namely:—
- 1. The rough product of distillation of herring-pickle.
- 2. The aqueous solution of the sulphate produced from it.
- 3. The pure crystallized, and by spirit of wine, precipitated sulphate of propylamine.
- 4. The concentrated solution of pure propylamine.
- 5. The aqueous solution of the sulphate prepared with No. 4.
Hitherto I have only experimented with the preparations No. 2, 4 and 5, in order to verify and complete the statements of the above paper. All these solutions are quite colorless and clear, like water; they diffuse already at some distance a strong odor of herring; but the pure aqueous propylamine, when smelt at closely, has a pungent odor, very similar to that of liquid ammonia, which, however, at a distance, assumes, as it has been said, the smell of herring. This odor is so peculiarly characteristic, that I do not doubt, that even in water-closets, in consequence of fermentation, propylamine is developed, particularly as woollen clothes easily acquire there the odor of {284} herring. All the conditions at least necessary for the formation of propylamine ammonia, and carbo-hydrogen, are to be found in water-closets. In a small close room its odor becomes insupportable, and affects strongly the head. Dr. Winckler, had therefore, good reasons to warn me against it. A young chemist, upon whose hand I dropped a very minute quantity of aqueous propylamine, for the purpose of ascertaining its taste, notwithstanding that he had been walking after that a considerable distance, and had been exposed to the air, smelt still, after some hours, so strongly of herring, that happening to to enter a company, he was spoken to about it by several persons. I mention this merely as a caution. The taste of pure aqueous propylamine is pungently alkaline, and hardly distinguishable from that of caustic ammonia.
The chemical re-actions of propylamine are well explained by Winckler. Turmeric paper turns brown with it, but being exposed to the air, in which propylamine quickly evaporates, it resumes again its primitive yellow color.
Sulphate of propylamine (No. 3,) appears in small splendid white prisms, exposed to the air it evolves a distinct smell of herring, and has a pungent saline taste, like sulphate of ammonia; it is entirely neutral, and when moistened with water, it does not alter the color either of blue or red litmus-paper, or of turmeric-paper.
We have in solutions of silver and iodine, which are not precipitated by ammonia, very appropriate re-agents for distinguishing propylamine from ammonia. Propylamine, however, treated with sulphate of silver, gave me not a white, but a yellowish-brown precipitate; and this result suggested to me the idea, that formiate of propylamine might be present. This precipitate was easily and perfectly dissolved in caustic liquid ammonia. With an aqueous solution of iodine I acquired at one time, according to the quantitative proportion a brown, and at another time a beautiful yellow precipitate, which dissolved in an excess of iodide of potassium. I usually employ an aqueous solution of iodine in iodide of potassium {285} instead of the tincture of iodine made with spirit of wine. The precipitate produced by iodide of potassium is, as I have just stated, either brown or yellow, provided that no excess of iodide of potassium be employed.—Buchner’s Neues Repertorium, Bd. 1.