thing to be attended to is the state of the patient. The symptoms resulting from administering a dose of arsenic capable of destroying life have been thus described. In about one quarter of an hour after taking the poison, sickness and great distress of stomach come on, followed by thirst and burning heat in the bowels; violent vomiting, severe gripings, and excessive and painful purging then ensue; then come faintings, with cold sweats and great debility; painful cramps and contractions of the legs and thighs succeed, with extreme weakness, and then death puts an end to these severe sufferings. In the progress of the dissolution the teeth are set on edge; the matter vomitted is of a brown or bloody nature; the stools are of an indescribable foetor; the pulse is frequent and irregular, the heart palpitates, the thirst is inextinguishable, the urine is of a red or bloody appearance; a livid circle comes round each eye, the whole body itches, and is covered with livid spots; the hair falls off the skin, comes away, and horrible convulsions usher in death. All these symptoms are seldom combined in the same individual, and sometimes they are altogether wanting. Mr. Earle has given a case of a woman resisting the effects of arsenic for four days: then she died; and, on being opened, the stomach and intestines were found to be most extensively ulcerated. Another instance is recorded by M. Chaussier, of a robust man who had taken arsenious acid, and died without any other symptoms than slight syncopes. On his stomach, the poison was found in the same state in which he swallowed it, and there was no appearance even of inflammation in the intestinal canal. In general, however, inflammation extends along the whole of this canal, from the mouth to the rectum. The above exceptions show, that neither state of the bowels is a decisive proof that poison has been administered. All these symptoms and results, even to the inflammation and ulceration of the

external

bowels, and of course death, are also produced by the application of arsenious acid to wounds. There is reason to believe that the inflammation of the stomach is more violent, when so applied, than when taken inwardly, which shows that it is not the immediate action of the arsenious acid on the stomach, but on the whole system, which produces death; and the stomach itself is only affected by some inexplicable alteration in the blood or nervous system.

When any symptoms, such as these now described, make it necessary to examine the contents of the stomach chemically, after the body is opened, a ligature should be tied round the oesophagus and round the beginning of the colon, and the intermediate stomach and intestines removed. Their liquid contents should be emptied into a vessel, and the stomach should be well washed with warm water. It has long ago been remarked, that the mixture of various substances, such as beer, tea, wine, oil, or soup, in the alimentary canal, make it difficult to detect arsenious acid, owing to these substances imparting peculiar colours to the tests, and preventing the arsenious indications. This difficulty has been lately removed by Mr. Phillips, who proposes, in an article published in a late Number in the Annals of Philosophy, that ivory black (animal charcoal) should be employed for this purpose. After making repeated experiments, he found, that by mixing ivory black with a coloured solution of arsenious acid, the colouring matter was in a few minutes so completely destroyed, that the usual tests might be readily applied. Supposing," he continues, the substance suspected to contain arsenious acid to have been boiled in distilled or pure water, and deprived of colouring matter by mixing ivory black with it, the test to which it may first be subjected is a solution of sulphuretted hydrogen gas in water." To this solution, which is clear and colourless, add, in a

66

wine-glass or phial, some of the suspected fluid; if it contain arsenious acid, a yellow coloured fluid will be produced, and after a few hours a yellow precipitate will fall down. Antimony produces a similar precipitate, but immediately, and the colour is darker.

Another test is sulphuret of copper. Add a few drops of an alkaline solution to the suspected liquid, and when mixed pour them into the sulphuret of copper; if arsenious acid be present, a green precipitate will be formed. To be certain that the sulphuret of copper contains no per-oxide of iron, add first to the solution some potash, if pure, a fine blue precipitate will be obtained; to this add the suspected liquid, and if arsenious acid be present, the blue precipitate will be converted to a green one. Nitrate of silver may now be applied to confirm the evidence of the other two tests. This was long considered as the most delicate, and one of the most decisive tests; but it has been observed that the alkaline phosphates produce, with silver, precipitates analogous in appearance to the arsenite of silver. This causes an ambiguity, which seems obviated, however, by a method recently proposed by Mr. Smithson, and improved by Mr. Phillips. It is this: put a little of the suspected solution into a glass tube or the bottom of an oil flask, drop into it a small crystal of nitre, evaporate the solution to dryness, and then heat it strongly in the same way. Add distilled water to the residuum, dissolve it, and then add nitrate of silver; if the solution, before heating, contained arsenious acid, it will now contain arsenite of potash, and a brick red precipitate will be the consequence of adding the nitrate of silver. When this test agrees with the others, the presence of arsenious acid in the substance operated on may be considered as proved. There is, however, still another and more conclusive test, which consists in reducing the arsenic contained in the acid to its metallic state. It has often been found difficult to effect

this, unless the arsenious acid was in considerable quantities; but Dr. T. S. Traill has lately published the following method of reducing the arsenic contained in very small quantities of arsenious acid to its metallic state: take a thin glass tube two inches and a half long and nearly half an inch in diameter; it should be closed at one end, and the open end should be slightly dilated like the common test tubes of the blow-pipe apparatus. By means of a piece of copper wire twisted round the upper part it can be attached to any convenient support at an angle of 35 deg., and its close end subjected to the flame of a spirit lamp. Put into this, with the substance suspected to be arsenious acid, black flux, or potash mixed with charcoal powder, to at least three times its weight; if the quantity is not very minute, to mix them with the point of a knife on writing paper before putting them in is sufficient: if it is minute, the two substances had better be mixed together in an agate mortar. The tube should be dry and clean, and its mouth may be stopped slightly with paper. After the substances are put into the tube, the lamp is placed under the closed end, and will soon raise it to a dull red heat; in less than two minutes, if arsenious acid be present, a shining metal crust will invest the upper side of the inclined tube, about half an inch from the flame. The tube may be preserved for further use, by shaking out the loose materials when it is cold, and scraping off the metallic crust from the inside. By this means, says Dr. Trail, I have succeeded in reducing less than one-tenth of a grain of arsenious acid to the metallic state; the metallic crust was distinct to the eye, and very conspicuous when a lens was employed.

AGE OF VEGETABLES.

All our readers know that there is a prodigious diversity in the age of vegetables or plants. Some live only for a few months, and others for a thousand years. Though the

apparent diversity amongst them is great, they are all reduced, as to their time of living, by some philosophers, into three classes those which arise in spring and die in autumn, those which live two years, and those which exist for a space betwixt four years and a thousand years. Plants which are of a soft, watery nature, and have tender organs, live only one, or, at most, two years; while those which have thicker juices, and stronger organs, with hard wood, live for many years. Among the shortlived ones, those which are almost destitute of taste and smell, do not, as a general rule, live so long as those which possess more volatile oil, and are of a fragrant nature. All sorts of corn, for example, live only a year, while common thyme, marjorum, wormwood, and hyssop, contrive to live for several. Bushes and small trees live from 60 to 100 years; and the vine, even in its hundredth year, has been known to be fruitful. Ivy and acanthus live more than 100 years; and the forest trees, such as oaks, chesnuts, beech, palm trees, olive trees, mulberry trees, the basbab, and cedars, live for 1000 years. Some of the cedar's of Lebanon (famous in remotest antiquity, as all readers of the Bible know, and in modern times for its fine forests,) have lived more than 1000 years. In Sicily there is a chesnut tree, called di centi cavalli, or "of a hundred horsemen," from so many having found shelter under its branches, also supposed to be more than 1000 years old: and there are still standing, in some of the forests of Germany, oak trees which are supposed to have served as temples for the Druids, and to have witnessed their superstitious rites. In Dodsley's Annual Register for 1758, an oak is mentioned as standing in Langley Wood, near Downton, Wiltshire, the property of the Bishop of Salisbury, which was supposed to be near 1000 years old. An oak was cut down not many years ago, at Morley, in Cheshire, which could be traced backwards for 800 years, and under which Edward the Black Prince

is said to have dined. In general, trees which grow quick do not live long, as pines, poplars, &c.; and the oak, which grows remarkably slow, and makes very hard wood, lives for a great length of time. In general, those which bear sweet and well-tasted fruits do not live so long as those which bear bad fruits, or do not bear any; and another difference observed is, that those which bear nuts live longer than those which bear berries or fruit with stones. Apple, apricot, cherry, and peach trees, however, live upwards of 60 years, and even longer, when they are carefully eleaned of the moss. In general, also, cultivated trees do not live so long as those which grow wild. When the earth about the roots of trees is dug up or loosened every year, they put forth leaves with greater vigour, and produce more fruit; but it has a remarkable effect in diminishing the length of their lives. On the contrary, it has been observed, that if this takes place only once every eight or ten years, it adds to the length of time they remain in a fruit-bearing condition, Cultivation of all kinds seems to hasten on the production, but it diminishes the number of years the plants live. Cutting and trimming plants adds to their existence. Lavender, when frequently cut and trimmed, has been known to live for more than 40 years.

HYDRAULICS.

CURIOUS EXPERIMENT.

THE following experiment has recently been exhibited in the northern part of this country, by a celebrated professor. A jet of water, by means of a great pressure, was made to spout upwards, and bear aloft, almost as high as the ceiling, a hollow copper ball as large as an egg; and sometimes an egg itself is used. The water was made to spout up in one unbroken jet, about the thickness of a lady's finger. Striking the ball on the under side, it spread out into a thin shell or film, which invested the globular surface on all sides,

and afterwards descended in rain or spray. The ball kept playing on the top of the jet, not leaping up and down, but vibrating a little from side to side, and generally it performed at the same time a slow vertical motion on its axis. It is remarkable, that it is not necessary for the water to rise in a vertical direction, The experiment succeeded, and the ball was supported equally well, when the jet was inclined ten or fifteen degrees.

A mode of Drying Damp Walls.Ir very often happens that apart ments on the ground floor, particularly if the house be situated near a common sewer or other receptacle for filth, are so damp that they cannot be successfully papered; and, if papered, the paper soon moulders and decays. To remedy such an evil, the following plan is recommended in a French journal: There was a large room which was always damp, and after a variety of means had been employed to render the walls dry, it was resolved to pull them down. Under these circumstances, it was recommended to wash them with sulphuric acid, which was done, the deliquescent salts were decomposed, and the room was afterwards perfectly dry.

SUBSTANCE FOUND IN THE MANUFACTURE OF PYROLIGNOUS ACID...

Of late this acid has attracted, and very deservedly, both from its scientific importance and its use in several arts, the attention of some of the most eminent modern Chemists; and various accounts

have of late been published of the best means of obtaining it, and of its properties. M. M. Macaire and Marcel have lately published, in a foreign journal, an account of a particular substance found during the rectification of this acid. It is perfectly transparent, having a strong grateful smell like ether. When evaporated from the hand it exhales an odour like oil of turpentine. Its taste is strong peppery, and burns the mouth. Distilled overy dry muriat of lime, its specific gravity is found to be 0.828. It boils at 65.5 of the centegrade thermometer,or 142.9 Fahr. It combines in any proportion with alcohol, forms an emulsion with water, and will not unite with oil of turpentine. On subjecting it to analysis, by means of the oxide of copper, it was found to contain

Carbon. Oxygen Hydrogen..

The pyro-acetic spirit, analysed by the same means, was found to contain in the 100 parts

Carbon Oxygen..

.55.30

.36.50

Hydrogen.. ... 8.20

A 100 parts of alcohol, of the specific gravity of 0.820, gave

Carbon Oxygen'. Hydrogen..

48.8

39.9

11.3

Bulletin des Sciences Technologiques,
Jan. 1824.

Whence these authors conclude that there exists at least two distinct simple vegetable fluids, which, like alcohol, form ethers with acids, and that these two fluids, which may be called the pyroacetic spirit, and the pyroxylic, differ from one another in their properties and in their composition.