Micro-chemistry of poisons, including their physiological, pathological, and legal relations : with an appendix on the detection and microscopic discrimination of blood : adapted to the use of the medical jurist, physician, and general chemist / by Theodore G. Wormley.

Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Micro-chemistry of poisons, including their physiological, pathological, and legal relations : with an appendix on the detection and microscopic discrimination of blood : adapted to the use of the medical jurist, physician, and general chemist / by Theodore G. Wormley. 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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    2. -pi.-- grain : almost immediately crystals begin to separate, and in a little time there is a quite good deposit. Under the microscope, the crystals present the appearances illustrated in Plate I., fig. 5, which readily distinguish them from the corresponding salts of potassium and sodium. 3. —grain : in a few moments small rough needles begin to form, and very soon there is a good crystalline precipitate, in form quite unlike that from potassium compounds. 4. ipLy grain : in a few minutes needles begin to separate along the margin of the drop, and after a little time there is a satisfactory deposit. 5. ^4-- grain : after some minutes, small needles appear; after some minutes more, there is a quite satisfactory deposit of needles, plates and cubes, which might readily be confounded with the deposit from dilute solutions of potassium compounds. 4. Nessler’s Test. When a solution of iodide of potassium and mercuric iodide in the presence of potassium hydrate is acted upon by ammonia, the latter is decomposed with the formation of an insoluble compound, known as dimercur-ammonium iodide, NHg2I,H20. The test-fluid is prepared by dissolving 20 parts by weight of pure potassium iodide in 50 parts of pure water, and adding mer- curic iodide to the solution until it is no longer dissolved, which will require about 30 parts of the mercuric salt. The liquid Avill now contain the double iodide of potassium and mercury, 2KI; Hgl2. The solution is diluted Avith three volumes of water, and the mixture alloAved to stand some hours, when any excess of the mercuric iodide Avill separate in the crystalline form. The fluid is then filtered, and tAvo measures of the filtrate mixed with three measures of a strong solution of potassium hydrate; this mixture is employed as the re- agent. Should the liquid become turbid upon the addition of the potash solution, it is again filtered. In the absence of mercuric iodide, the reagent mixture may be prepared by treating a solution of potassium iodide with a saturated solution of mercuric chloride, until a slight permanent precipitate is formed; a strong solution of potassium hydrate is then added, and the mixture alloAved to stand until the liquid becomes clear, when it is decanted.
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