feather, into the throat. By persisting in this treatment many persons poisoned by arsenic have recovered.

Of the antimonial preparations there is scarcely any likely to be administered, or to be taken internally, so as to produce death, except tartar emetic, which is a triple salt composed of tartrate of potash and protartrate of antimony united together. This salt is usually administered as an emetic, and it generally acts in that way with great violence. When vomiting does not take place it acts as a poison, occasions violent spasms of the esophagus and neck, which prevent the possibility of swallowing. When it is administered to dogs, and their oesophagus is tied up so as to prevent vomiting, the consequence is death. When a person is poisoned with tartar emetic, our object should be to produce vomiting, and for this purpose warm water is the most efficacious remedy. The decoction of yellow bark likewise, proposed by Berthollet, is of service, when administered in such quantities as to decompose the salts.

Perhaps no poisons are so frequent as the preparations of copper. This metal is used for so many purposes connected with the preparation of food, it is so easily oxidized, and all its compounds are of so deleterious a nature, that many instances must occur of injurious effects from it. The most common preparations of copper likely to be applied as poisons are verdigris, acetate of copper, sulphate of copper, nitrate of copper, muriate of copper, and copper dissolved by fat. The taste of all these preparations is exceedingly disagreeable; but they may be mixed in small quantities with food without being perceived. The preparations of copper occasion violent colics, vomiting, prostration of strength, and death. The best antidote is sugar, either swallowed solid, or dissolved in water. It should be taken both ways, and in considerable quantities. The liquid induces vomiting, and thus gets rid of a portion of the poison.

The only preparation of tin likely to be used as a poison is the muriate which is used in considerable quantities by the dyers. Its taste is exceedingly nauseous. It qccasions violent colics, vomiting, and death. The best antidote is milk, which, when drank in considerable quantity, seldom fails to care the patient, by decomposing the salt and removing all the disagreeable symptoms.

Zinc is so little employed for culinary purposes that it is but rarely that it can act as a poison. The sulphate of zinc, however, is so common a salt, that it has been often administered in considerable quantities by mistake. It is by no means a dangerous poison; for it acts speedily as an emetic, and is thrown out of the system before it has time to produce bad effects. The business of the physician is to promote this effect by making the patient swallow considerable quantities of warm water. Milk also, which decomposes the salt, may be administered with advantage.

Nitrate of silver is well known as one of the most corrosive salts employed in pharmacy. When introduced into the stomach it soon

occasions death, by corroding that organ, and bringing on gangrene. When injected into the veins, even in very small quantities, the animal dies almost immediately. The antidote to this poison is common salt dissolved in water, which decomposes the nitrate of silver, and forms an insoluble chloride, which produces no injurious effects upon the animal economy.

Gold is not likely to be administered as a poison. When this metal is dissolved in nitro-muriatic acid it fórms a salt, which acts more violently on the animal economy than corrosive sublimate. The symptoms are similar, except that the salt of gold does not produce the same effects upon the mouth and gums. No antidote against this poison is known. The object of the physician must be to get it thrown out of the stomach as speedily as possible by vomiting. I think it very probable that a solution of sulphate of iron would destroy its deleterious effects, by decomposing the salt, and throwing down the gold in the metallic state.

The nitrate of bismuth, and the white pigment for the face, known by the name of pearl white, which is a preparation of bismuth, act with considerable energy as poisons when introduced Into the stomach. The best antidotes against these deleterious preparations are milk and mucilaginous liquids, swallowed in considerable quantities.

Sulphuric acid has sometimes been swallowed by mistake, and sometimes taken by persons who wished to destroy their lives. The violence of its action on animal substances is well known. The mouth, the esophagus, and the stomach, are speedily corroded by it, and their functions destroyed; the consequence is death, attended with the most excruciating pain. From the experiments of M. Orfila it appears that the best antidote against this corrosive acid is calcined magnesia, and that if this substance be administered soon after the acid has been swallowed, it prevents death, and enables the patient to recover.

Nitric acid has been frequently swallowed in considerable quantities by unhappy persons who wished to destroy themselves. It is still more corrosive than sulphuric acid, acts with more violence, and produces dreadful pains. Magnesia is also the best antidote against this poison, and if administered very speedily, it may even save the life of the patient.

Muriatic acid, though it cannot be exhibited in so concentrated a state as sulphuric and nitric acids, produces the same deleterious effects when taken internally, and speedily occasions death, attended with the same dreadful symptoms. Magnesia is likewise the best antidote against this acid.

Phosphoric and fluoric acids, sulphurous acid, phosphorous acid, are all likewise poisonous; but as the chance of their being introduced inadvertently into the stomach is not great, it does not seem necessary to dwell upon them. M. Orfila likewise ranges oxalic and tartaric acids among poisons; but he gives no instance of their deleterious effects.

Caustic potash and soda are not less corrosive than the concentrated acids; hence, when introduced into the stomach, they act with equal violence, and very speedily destroy life. The best antidote is vinegar, administered in such quantity as to neutralize the alkali.

Ammonia likewise acts with eonsiderable violence upon the animal economy when swallowed, and produces convulsions and death. Vinegar answers equally well as an antidote against ammonia as against the fixed alkalies.

Barytes, carbonate of barytes, and muriate of barytes, are known to act as violent poisons when introduced into the stomach. The effects which they produce are similar to those produced by the other corrosive poisons. An alkaline sulphate by converting the barytes into an insoluble sulphate, which does not act upon the human body, is the best antidote against this poison.

Lime is not a very energetic poison, yet when swallowed in considerable quantities, it destroys life by the inflammation which it induces in the stomach. The same mode of treatment answers for lime that was recommended in the case of poison by the fixed alkalies.

Phosphorus, when introduced into the stomach, always proves fatal. It is gradually converted into phosphorous and phosphoric acids, which corrode the stomach and intestines, and produce inflammation. The object of the physician should be to throw the phosphorus out of the stomach as speedily as possible by means of an emetic. When the phosphorus has been introduced in the state of extreme division it is useful to make the patient swallow large quantities of water, holding magnesia in suspension. The liquid, by filling the stomach, prevents the phosphorus from being readily converted into an acid, and the magnesia neutralizes any acid that may be formed.

M. Orfila introduces pounded glass and stone-ware among the number of poisons. He gives a number of cases in which these substances were swallowed without any inconvenience, and others in which they produced destructive effects. It is obvious that these. substances act only mechanically. It must depend upon accident whether any of their sharp points wound any part of the stomach and intestines, or whether they make their way without inflicting any wound.

Cantharides, lytta vesicatoria, or Spanish flies, are a set of insects well known in the materia medica, as they constitute the essential ingredient in the common blistering plaster. Cantharides, according to the analysis of M. Robiquet, contain a variety of different substances; but the most important is a white substance, having the form of snall crystalline plates, insoluble in water, soluble in boiling alcohol; but is deposited on cooling in small crystalline plates like spermaceti. It is soluble in oils. It possesses the listering property in great perfection, and is the only substance in canth rides that has it.

The effect of cantharides when taken into the stomach in any quantity is well known. It produces a most furious satyriasis, which usually terminates in gangrene and death. No antidote against this formidable poison has been hitherto discovered.

All the preparations of lead are poisonous; but those most likely to be taken into the stomach are the oxides of lead, white lead, litharge, and sugar of lead. The water near lead mines, in which the galena is washed, is usually injurious to the health, in consequence of particles of that substance which it holds in suspension. The fumes of lead prove no less injurious to those who are exposed to them.

Lead shows its deleterious effects in those who are exposed to its action; but slowly. Obstinate costiveness and violent colics, known by the name of colica pictonum, first attack the patient. This is followed by paralysis and death. It appears from the experiments of M. Orfila, that sulphate of magnesia acts as an antidote against acetate of lead. An insoluble sulphate of lead is formed, which does not injure the animal economy, and the acetate of magnesia acts merely as a purgative. The common method of treating persons poisoned by lead is by a course of purgative and emetic medicines, which seldom fail to cure the patient.

In an appendix M. Orfila gives us a set of experiments on iodine, introduced into the stomach of animals. In small quantities it acts as an exciter. When administered to the amount of about half an ounce it occasions death, if the animal be prevented from vomiting, gradually corroding the stomach and intestines. When taken in larger quantities it destroys life even though the animal be allowed to vomit.

In another appendix M. Orfila shows by experiment, that charcoal powder is not an antidote against corrosive sublimate and white oxide of arsenic, as had been advanced by M. Bertrand.

ARTICLE XII.

Proceedings of Philosophical Societies.

ROYAL SOCIETY.

ON Thursday, the 6th of April, a paper by Mr. Knox was read, on the coloured rings formed when a flat plate of glass is pressed against a convex lens. Mr. Knox conceives that the reason why neither Sir Isaac Newton, Dr. Herschell, nor any other philosopher, was able to give a satisfactory explanation of these coloured rings, was, that they were not acquainted with all the phenomena. He made his experiments according to the method pointed out by Dr. Herschell in his paper on the subject published in the Phil. Trans. for 1804. Mr. Knox described a great many new phenomena

which he observed, and of which it is scarcely possible to give an idea without the assistance of figures. He found the phenomena the same when the experiments were tried in vacuo as in the open air. Nor did the introduction of water between the plates alter the phenomena much. Hence he conceives that the rings are not owing, as Newton supposed, to the film of air between the plates. He conceives them to be derived from the reflection of the surface of the glass next the film of air. The changes induced by the passage of the ray from one medium into another may occasion such refractions as to collect together the different bundles of coloured rays so as to produce the coloured rings.

On Thursday, the 13th of April, a paper by Major Rennell was read, stating further proofs in confirmation of the existence of a current setting upon the Scilly Islands, in the chops of the Channel. He adduced three proofs that there exists a current running east along the north coast of Spain. The French navigators are aware that there is a current which sets north along the west coast of France, and it is obviously the Spanish current which has received a northerly direction, from the position of the land. All the sand and alluvial matter which is brought into the Bay of Biscay by the Garonne, the Loire, and the other rivers which empty themselves into the sea on the west coast of France, is found on the north side of the mouths of the respective rivers, and not on the south, a circumstance which can be occasioned only by a northerly current. He brought several facts showing that a northerly current exists about lat. 49° at the mouth of the Channel, and rendered it probable that it flows also westerly, as well as north. This current flows at different times with different velocities, and this he assigned as the probable reason why it was not discovered sooner.

There is a current likewise which flows east along the south coast of Ireland, and meeting with the first described current, flows northward into St. George's Channel, and moves in the direction to Cardigan Bay. This current is the cause why ships are so frequently driven into that bay. There is a current which runs up along the west coast of Ireland, turns cast along the north coast, and then flows south certainly as far as Dublin, and probably further. There is another current that flows north along the west coast of Scotland, bends round the northern part of the island, and flows south along the east coast of Great Britain as far as Harwich, where it meets with the current in the English Channel. These produce a current north-east along the coast of Flanders and Holland; it then proceeds north along Jutland, receives the current coming out from the Baltic, proceeds to the Naze of Norway, and then runs north along the coast of that country.

On Thursday, the 20th of April, a paper by Sir Humphry Davy on a combination of iodine and oxygen, was read. The author in a former paper had given an account of several unsuccessful attempts to form this compound. It occurred to him that if euch rine gas (oxide of chlorine) were made to act directly on iodine, the