CHLORIDE OF BARIUM.

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tincture of nutgalls, or caustic ammonia, by which the absence of metallicmatter (as iron, lead, or copper), may be inferred. If excess of sulphuricacid be added, the filtered solution should be completely volatile whenheated, and should occasion no precipitate on the addition of carbonateof soda, by which the absence of lime or magnesia is proved.

Physiological Effects, (a.) On vegetables. —This salt is poisonousto plants (Marcet, quoted by Decandolle, Phys. Veget.)

(. b .) On animals. —The action of chloride of barium on animals is, ac-cording to Sir B. Brodie [Phil. Trans. 1812, p. 205), analogous to that ofarsenic. Locally it operates as an irritant. After absorption it affects thenervous system, the organs of circulation, and the stomach. Its actionon the nervous system is manifested by staggering, convulsions, paralysis,and insensibility; on the circulating system, by palpitations, with feebleand intermittent pulse ; on the stomach, by vomiting from its applicationto a wound. According to Sir B. Brodie the affection of the stomach isslighter than that caused by arsenic. (See also the experiments of Orfilain the Toxicol. Gener., and of C. G. Gmelin in his Versuche uber die Wir-Icungen, &c.)

(c.) On man. —Administered in small doses, it at first produces novery obvious effects. In some cases the appetite appears to be improved.Soon we observe an increased secretion of urine, tendency to sweating,and not unfrequently loose stools. With no other obvious symptomsthan these, glandular swellings or enlargements sometimes become softerand smaller, from which we infer that the absorbent system is stimulatedto greater activity. If we persevere in the use of gradually increaseddoses, the appetite becomes disordered, nausea and vomiting, with notunfrequently griping and purging, come on: a febrile state, with drytongue, is produced, the nervous system becomes affected, and the patientcomplains of giddiness and muscular weakness. Sometimes, accordingto Schwilgue ( Traite de Mat. Med. vol. i. p. 441, 3 me . ed.) under thecontinued use of it, catarrhal discharges from the eye, nose, ear, &c. takeplace; inflamed or suppurating lymphatic glands evince signs of anaugmented excitation, wounds assume a more healthy appearance, and,in some cases, cicatrize.

In large medicinal doses very unpleasant effects have been occasionallyobserved from its use; such as vomiting, purging, sometimes griping,contracted pulse, giddiness, and great muscidar debility, almost amount-ing to paralysis, with trembling. (See an illustrative case in MedicalCommentaries, -Sri'S.. 267.)

In excessive or poisonous doses (as an ounce) the affection of the ner-vous system is more obvious. In one recorded case the symptoms wereconvulsions, pain in the head, deafness, and, within an hour, death. ( Journ.of Science, vol. ix. p. 382.)

In conclusion, it may be observed, that considered medicinally chlorideof barium is most analogous to, though more powerful than, chloride of cal-cium, and is applicable in the same cases : regarded toxicologically it maybe compared to arsenic, but it acts less energetically on the stomach, andmore rapidly on the nervous system, and causes death in a shorter time.

Uses. —The principal medicinal use of chloride of barium is in thetreatment of scrofula, for which it was introduced into medicine by Dr.Crawford in 1790 (Med. Commentaries, Dec. 2d, vol. iv. p. 433, andMed. Communications, vol. ii.), and was subsequently employed by Hufe -