BICYANIDE OF MERCURY.
487
filter, and crystallize. In this process double decomposition takes place,the resulting products being water and bicyanide of mercury.
REAGENTS.
2 eq. Hydrocyanic Acid 54 {* % *
1 eq. Binoxide Mercury 218 ^ mS"" 202
Properties. —The primary form of the crystals of this salt is the rightsquare prism. The crystals are heavy, white, colourless, transparent oropaque, inodorous, and have a strong metallic taste. They are solublein water, both hot and cold, and very little, if at all so, in alcohol.
Characteristics. —Perfectly dry bicyanide of mercury when heatedyields metallic mercury and cyanogen gas. The latter is known by theviolet or biuish red colour of its flame. Heated with hydrochloric acidit evolves hydrocyanic acid. It is not decomposed by nitric acid or thealkalies. Its solution throws down a black precipitate with hydrosul-pliuric acid, and pearly crystalline plates ( hy dr argyro-iodo-cy ankle ofpotassium) with a concentrated solution of iodide of potassium ( videp. 289).
Composition. —Its composition is as follows:—
Eq. Eq. Wt. Per Cent. Gay-Lussac.
Mercury . . . . i . . . 202 . . . 79*52 . . . 79*91
Cyanogen . . . . 2 ^ . . 52 . . . 20*47 . . . 20*09
Bicyanide of mercury 1 . . . 254 . . . 99*99 . . . 100*00
Purity. —When prepared from ferrosesquicyanidc of iron (Prussianblue ) the crystals are usually yellowish, from the presence of some oxideof iron.
Physiological Effects, {a.) On vegetables. —It acts on plants likebichloride of mercury (Goeppert, in Decand. Phys. V'eg. 1334).
(b.) On animals. —Coulon ( Traite sur VAcide Prussique, quoted byWibmer, Wirk d. Arzneim. iii. 30) found that it acted on dogs, cats,sparrows, frogs, snails, &c. like hydrocyanic acid. After death, inflam-mation of the stomach was observed. Ollivier d’Angers ( Journ. de Chim.Med. i. 269) tried its effects on dogs. Seven grains, dissolved in water,killed a small dog in ten minutes, under attempts to vomit, general con-vulsions, and exhaustion, manifested alternately; respiration and circu-lation at first accelerated, afterwards diminished. Similar effects wereproduced by applying the salt to the cellular tissue, or injecting it intothe veins. Tiedemann and Gmelin ( Versuche u. d. Wage auf welch.Subst. aus cl. Magen u. Darmk. ins Blut gelang.) detected mercury in theblood of the splenic vein of a horse to whom the bicyanide had beenadministered.
(c.) On man. —Taken in small doses, it very readily excites nausea andvomiting. Parent [Journ. de Chim. Med. viii. 473) says it does not pro-duce the epigastric pain which the bichloride of mercury readily occasions.Continued use causes salivation. In one case, one-eighth of a graintwice a day caused ptyalism in three days (Neumann, in Dierbach ’sNeueste. Entd. in d. Mat. Med. ii. 483,1828). Mendaga ( Decades Medico-chirurgicas y Farmaceuticas, vi. 319, in Richter’s Amfu.hr Arzneim. v.477) says it acts directly on the skin and bones, and hence it sometimesvery speedily allays the pain of and disperses nodes.
RESULTS.
- 2 eq. Water. 18