Bismuthi Trisnitras. Lond. Trisnitrate of Bis-muth

"Take of bismuth, one ounce; nitric acid, one fluid ounce and a half; distilled water, three pints. Mix six fluid drachms of the distilled water with the nitric acid, and dissolve the bismuth in the diluted acid; then decant the solution. Add to it the remainder of the water, and set it apart that the powder may subside. Next, having poured off the supernatant fluid, wash the trisnitrate of bismuth with distilled water, and dry it with a gentle heat."

Dublin.

"Take of bismuth in powder, seven parts; nitric acid diluted, twenty parts; distilled water, one hundred parts. Add the bismuth gradually to the acid, and dissolve by the aid of heat. Mix the solution with water, wash the precipitate with distilled water, and dry on blotting paper with a gentle heat,

Syn. (Sub.) Nitrate de Bismuth, Blanc de Ford (F.), Saltpetersaurer Wis-muth (G.), Termassido Bianco de Bismuto (I.).

In this process, the nitric acid is partially decomposed, and the bismuth oxidised; and being thus rendered soluble, in the remainder of the acid a solution of the nitrate of bismuth is obtained. This solution, when filtered, is colourless and transparent; reddens the tincture of litmus, and has a harsh, caustic taste; and, were the process stopped here, crystals of the nitrate might be readily obtained by evaporation. The affinity of the acid for the oxide in the nitrate is, nevertheless, so slight, that it can be separated from it by water; and this is effected in the second part of the process; for the water then added combining with the greater part of the acid, and depriving the fixed oxide of its solubility, this is precipitated, in combination with some water, and the remainder of the acid, forming the trisnitrate of bismuth.1 It is, in fact, a hydrated oxide of bismuth, combined with a small proportion of the nitric acid. The supernatant fluid contains in solution a nitrate of bismuth, with an excess of acid.

The oxide of bismuth consists of 90 parts of bismuth and 10 of oxygen in 100 parts2 or of 1 eq. of bismuth = 71 + 1 of oxygen = 8, making the equivalent 79 : the nitrate consists of 3 eq. of oxide of bismuth = 327, + 1 of nitric acid = 54.15, making the equivalent 291.15.

1 Traite de Poisons, etc. vol. i. p. 182.

Qualities. - The trisnitrate of bismuth is a pure white, inodorous, insipid powder. It is soluble in the strong acids, from which it is readily precipitated by water; thence it is insoluble in that fluid, and, for the same reason, in very dilute acids. It is soluble in ammonia, although this salt precipitates it from the nitrate; but is very sparingly soluble in potassa and soda. It is blackened by sulphuretted hydrogen gas, its solution in water, and all the hydrosulphurets. When mixed with charcoal and exposed to a strong heat, the trisnitrate is decomposed, and the bismuth reduced to its metallic state.

Medical properties and uses. - Trisnitrate of bismuth is tonic and antispasmodic. It has been advantageously administered in spasmodic affections, palpitations of the heart, and epilepsy. We have found it extremely beneficial in pyrosis, gastrodynia, and some other varieties of dyspepsia; in which cases we have usually combined it with extract of hops; and when there have been merely atony of the digestive organs, without organic mischief, it has proved almost uniformly successful.3

The dose of the trisnitrate is from one grain to twelve or fifteen grains. In very large doses, however, it acts with great violence, producing nausea, vomiting of a white, ropy matter, pains in the stomach, acute colic, heat of the chest, and alarming anxiety; and when these symptoms are accompanied with rigors, sighing, vertigo, and convulsions, the poison always proves fatal. Post-mortem examinations exhibit appearances of inflammation and ulceration of the stomach; inflammation of the duodenum and jejunum : the lungs are gorged with blood of a deep-red colour, so as to resemble liver. It is easy to explain the inflammatory and corrosive effects of the trisnitrate on the coat of the stomach into which it is introduced; but the effect on the lungs is less obviously explained; unless we suppose the poison to act sym-

1 It was formerly known by the name of Magistery of Bismuth.

2 Phillips's Trans, of the Pharm. 1824.

3 It was first employed in these cases by Professor Odier of Geneva. See Manuel de Medecine pratique, etc. par Louis Odier, pathetically through the nerves, as well as locally on the animal fibre. In cases of poisoning by trisnitrate of bismuth, both general and local blood-letting must be resorted to; whilst the patient should drink freely of milk and mucilaginous fluids. Fomentations and emollient glysters are also necessary: the degree of inflammation being such as to render the employment of ordinary purgatives hazardous.

When trisnitrate of bismuth has been employed as a poison, it is detected by its chemical properties, and the effects of re-agents upon it. When the whole has been taken, the only certain method of ascertaining the nature of the poison is to dry a portion of the vomited matter, or of the contents of the stomach if it have proved fatal; and to calcine the mass, mixed with charcoal, in a covered crucible, so as to reduce the metal, in which state it is easily recognised.