All the soluble compounds of this earth are poisonous, especially the _muriate_; which, whether injected into the veins, introduced into the stomach, or externally applied to an abraded surface, will occasion death in a very short period. We are not aware that any case stands recorded of poisoning by baryta. _Orfila_[334] and _Brodie_[335] have, however, investigated the symptoms which this poison produces on animals, and they appear to be analogous to those occasioned by the ingestion of arsenic. The muriate, on account of its greater solubility, would appear to be much more active than the pure earth, or its carbonate. _Physiological action of Baryta._ Barytic poisons require to be absorbed before they act on the system; they may therefore destroy by external application, although it would appear that, unlike arsenic, they act sooner when internally administered. _Mr. Brodie_ thinks that the _muriate of baryta_ occasions death by acting upon the brain and the heart; at the same time it exerts a local action, and corrodes the viscus with which it comes into contact. _Antidotes._ It has been shewn by the experiments of _Orfila_, that the soluble sulphates, as _Glauber_ or _Epsom salts_, by converting the _baryta_ into an insoluble _sulphate_, will act as antidotes to its virulence. In the first instance, therefore, it will be prudent to produce this chemical decomposition in the poison, and then to expel it, as quickly as possible, by emetics. _Chemical tests for the detection of Baryta._ Where the pure earth, _baryta_, or its solution in water, is presented for our investigation, it may be identified by the following reagents. (_a_) _Sulphuric acid, and the soluble sulphates._ These bodies precipitate from the barytic solution, a white _sulphate_ of the earth, insoluble in water, and nitric acid. (_b_) _Carbonic acid gas, and the alkaline sub-carbonates_, produce in it a white _carbonate of baryta_. (_c_) _Muriatic acid_ combines with baryta, and furnishes a salt which is capable of being identified by numerous reagents. _M. Orfila_ has furnished us with the following satisfactory compendium of its habitudes. “A salt which does not redden the tincture of tournesol, which does not turn the syrup of violets green, which is not precipitated by the alkaline hydro-sulphurets,[336] nor by ammonia; but which, on the contrary, is precipitated by the sub-carbonate of ammonia, soda, or potass; which is not soluble in concentrated alcohol; which furnishes, with the sulphate of potass, or the sulphuric acid, a white precipitate insoluble in water and in the nitric acid, and which gives with the nitrate of silver a curdled precipitate of muriate of silver, likewise insoluble in the nitric acid, _can be no other than the muriate of baryta_.”