The plant alkaloids / by Thomas Anderson Henry.

Date:
1913
Catalogue details

Licence: In copyright

Credit: The plant alkaloids / by Thomas Anderson Henry. 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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    the type, B.AuCla, are also sometimes produced, and under certain conditions aurichlor-derivatives of the alkaloids, containing the group AuClg in place of a hydrogen atom of the alkaloid, are formed. Examples of such compounds are referred to under japaconitine (p. 349) and caffeine (p. 314). The aurichlorides of the solanaceous alkaloids are especially useful in separating and characterising the members of this group. Platinic Chloride. Similar compounds, the platinichlorides, (B.HCl)2.PtCl4 or B.HgPtClg, in the case of diacidic alkaloids, are formed with platinic chloride, but as a rule these are more soluble than the aurichlorides, especially in dilute hydrochloric acid. Mercuric Chloride. With solutions of this salt many of the alkaloids give characteristic, crystalline mercurichlorides of the general composition, B.HCl.HgCL. Among other precipitants of this class may be mentioned ferric chloride, lead tetrachloride, telluric chloride, and thallic chloride. Solutions of certain double metallic haloids form the best known group of alkaloidal precipitants and include the reagents most commonly used for detecting their presence. Among these are the following. Potassium Mercuric Iodide [Mayer's Reayent). This is best prepared by adding 6-8 grin, of mercuric chloride, dissolved in water, to 26 grm. of potassium iodide, dissolved in water, and diluting to 1000 c.c. This solution gives white, curdy precipitates with minute traces of alkaloids in solutions slightly acidified with hydrochloric or sulphuric acid. The precipitates vary in composi- tion with the conditions of precipitation. The alkaloids may be recovered from these precipitates by suspending them in water and passing a current of sulphuretted hydrogen, when the alkaloidal hydriodide is formed and may be recovered by concentrating the filtrate. Similar precipitates are afforded by solutions of potassium bismuth iodide (Dragendorff’s reagent), potassium cadmium