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dulge delicious error? Yet, though the inevitable stroke cannot be turned aside, its destructive effects maybe lessened; and an investigation of the real action of thunder will conduct us to the proper principles."

We have some doubts of the accuracy of this theory. The Professor states, that when the " lowest verge of the cloud touches the ground, a total discharge is made;" and also, " that the cloud rolls towards the nearest and most elevated objects." We would, therefore, beg leave to ask, when a communication is established between the earth and the cloud by a lightning conductor, if a total discharge will not be made? if this, in fact, does not take place on a small scale in all discharges of the electrical machines; and, in fact, whenever a cloud comes in contact with a tree, a rock, or a spire? We would further ask, if a lightning conductor may not, like a tree or a spire, establish a connexion between the earth and the cloud, and discharge it? But the Professor gives up the only practical point worth contending for, when he recommends that ribands of copper should be extended from masts of ships to their keels. We have no theory on this subject, and do not pretend to account for these facts; but if they are correct, the Professor's objections to lightning conductors are unsatisfactory. We believe, nobody ever expected that a rod Should equal a mountain in capacity; but it may harmlessly communicate the electrical stroke from a cloud to the ground, and carry that stroke past the house. At the same time, we readily admit that he has stated so many circumstances which show the possibility of opposing currents of aircarrying off electricity, that we cordially subscribe to the notion of a rousing kitchen fire being a good preventive against a house being struck, and wish that all men were in a condition to employ so cheerful a guard.

ACTION OF HYDROCYANIC ACID ON THE ANIMAL ECONOMY.

As a medicine this acid has been extensively tried in France, Germany, Italy, and our own country, and several treatises have been published extolling its virtues, and describing the wonderful effects which it is capable of producing. It is chiefly efficacious in complaints of the chest, and its exhibition, even in these affectious, requires (as we have been informed) considerable discrimination. But this, like many other remedies which have been indiscriminately praised, does not enjoy the extensive reputation it once did. When a new remedy is proposed, its virtues are frequently overrated. The cases in which it is tried happen to be benefited during its exhibition, and the new medicine gets the credit; other causes, which may have materially assisted, being left out of the question. Indolent persons, glad to have any excuse for not exerting themselves, seeing that the vaunted remedy does not answer their expectations, readily cast it aside, without endeavouring to draw a line of distinction between the cases in which it is of use and those in which it is mischievous. Thus from misdirected enthusiasm on the one hand, and indolence on the other, really valuable remedies often meet with neglect. This medicine, when taken in too large doses, produces instantaneous death. From the Annates de Cliimie for October 1814, we learn that a professor of chemistry inadvertently left on his table a phial filled with a solution of prussic acid in alcohol, and that a female, seduced by its agreeable smell, drank a small glass full of it, and soon expired, as if struck by apoplexy. In Dr. Granville's Treatise* on this acid, we find the following case; it is taken from Hufeland. D. L. a robust and

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healthy man, aged thirty-six years, on being seized as a thief by the police officers, snatched a small sealed phial from his pocket, broke off the neck of it, and swallowed the greatest part of its contents. A strong smell of bitter almonds soon spread around, which almost stupified all present. The culprit staggered a few minutes, then, without a groan, fell on his knees, and sunk lifeless on the ground. Medical assistance being called in, not the slightest trace of pulse or breathing could be found. A few minutes afterwards, a single and violent expiration occurred, which was again repeated in about two minutes. The extremities were perfectly cold, the breast and abdomen still warm, the eyes half open and shining, clear, lively, full, almost projecting, and as brilliant as those of the most ardent youth under violent emotion. The face was neither distorted nor convulsed, but bore the image of quiet sleep. The corpse exhaled a strong smell of bitter almonds, and the remaining liquid being analyzed, was found to be a concentrated solution of prussic acid in alcohol. 'Several cases are also on record of poisoning by the distilled water of the cherry laurel, the leaves of this plant, and the essential .oil of almonds, which we have not room to insert.* All of them, however, show the dreadful effects which substances containing the prussic acid are capable of producing. The modu* operandi of hydrocyanic acid appears to be through the medium of the nervous system; and wewill here relate one or two of the experiments made with this substance on animals, by M. Orfila,-f to show the symptoms it produced. Experiment \st. Two drops of prussic acid were given to a young dog; immediately afterwards the respiration was accelerated, its step became unsteady, the animal fell, made water in abundance,

* Vide Paris and Fonblanque on Medical Jurisprudence, vol. ii. p. 400. - t Traitedes Poisons, par M. P. Orfila, torn, ii. p, 166.

and vomited twice; in a short time it recovered. In five hours' time eight drops more were given to it, when the animal instantly experienced the following symptoms : — cough, flow of saliva, quickened respiration, weakness of the hinder extremities, plaintive cries, purging, bending of the body backwards, dilatation of the pupils, rigidity of the muscles, and in less than five minutes, paralysis of the hind feet first, then of the fore feet; general insensibility, ex-ceptiug of the rump, which was occasionally agitated; acceleratedpulse, from 72 to 150 in the minute, great mobility of the eyes and eyelids, and at last complete stupor. Fifteen minutes after this the animal arose, voided its urine, bent the body backwards, and in half an hour was restored. On the following day, sixteen drops of the same poison were again given to this animal. Instantly, quiokened respiration, very violent cries, convulsions, opisthotonos (bending-of the body forwards), then emprosthotonos (the contrary motion), the fore feet placed on the head, general tetanus, dilated pupils, ears stiff, urine copious, general paralysis, lapping of the tongue, eyes fixed, eyelids in motion. Five or six minutes afterwards, respiration difficult, trismus irregular and unexpected movements. At the end of half an hour the animal raised itself, and appeared to suffer in the stomach; was frightened at the least noise, sought the dark, and greatly trembled. One hour after, it ate with a voracious appetite.

Etperiment Id. When thirty or forty drops of prussic-acid were administered to dogs or cats, they put forth cries more or less violent, had convulsive motions, and expired six, twelve, or fifteen minutes after taking the poisonous substance.

On examining the bodies of animals or persons poisoned by this acid, no traces of inflammation are to be observed; there is congestion of the veins, whilst the arteries are empty. We are not

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FRAGRANT LAMPS.

Mk. Editor,—Perhaps you may thank me for the following little account of a method of preserving the air of. • apartments comparatively pure, and at the same time of dispersing a pleasant fragrance through them. liy means of a wire fixed to one side or at the back part of the lamp, according to its nature, and bent at right angles, so as, to he a few inches above the top of the flame, a piece 6f sponge is to be suspended. This is to be soak©!' in a mixture of best vinegar Anil water, and squeezed nearly dry before it is hung up. By this means the vinegar is constantly dispersed through the apartment, and gives a very fragrant smell. It would probably be very useful in manufactories and close, workshops, and is of course as easily ,J appHcaWe to gas as other lights. It costs very little, for the same 'piece of sponge has served me a 'Wfcole' winter. It must be ooea'sionally re-immersed in the water 'arid vinegar, and then will be found (to give out a great quantity of soot, which otherwise fouls the air of the apartments. •■'.•■••! -nt -ju •* I ' !■■ Your obedient servant, -f ■';i'J - Ein Deutsche*. -,

iliiitua 3i!i it .... In liiii* ».i

'.rf^isriscTidk Of pbii'tjtvE;.

-m; /AND NEGATIVE ELBCTRI

aii!\4xm.h,,-> ,.'■'.'„--;.ijr ;; .",

u PjOBlTiye. and negative electricity u may be readily distinguished by .??.the taste, on making th,eelectric /<ie#rrent pass by,means of a point «i onto the tongue.. TJjMasto.ortke,, positive electricity is acid; thai of

the negative electricity is more caustic, and, as it were, alkaline.—

Berzelius.Journal of Science.

PRESERVATION OF SEEDS.

The late M. Zea, the celebrated Peruvian botanist, asserts, that the most delicate seeds of American plants may be sent to Europe in the highest preservation, by being enveloped in that kind of raw brown sugar which always keeps its humidity. When th.e seeds are to be sown, it is only requisite to immerse them in lukewarm water, which will take oil' the sugar.

: 4r—

NATURAL CARBONATE^ OF SODA. M. Rivero, of Santa F6de Bogota, informs us, that he finds the following to be the constituent parts of the natural carbonate of soda of the lake of Merida, in Colombia :—

Carbonic acid 0.390ft

Soda O.flfe '.: '■

Water 0.1880

Loss 0.0098

Jameson's Philosophical Journal.

COLOURED FLAj

Add a little boracic acid to a spoonful of alcohol, and stir them together in a saucer or cup,-then set them on lire, and the flame will be of a beautiful green colour.; If strontites in powder bfe added to alcohol, it burns with a carmine flame; if barytes .be"added; the flame is .yellow; if the alcohol cdntain muriate of magnesia, it burds .with, a reddish-yellow flame.';

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TO MAKE AND DESTROY (Via' ■fl?0bilOVRS. vtij 'k Drop'as' much sulphate of copper, into w'afev as forms a colourless solution, add a little ammonia, whiciT is equally-colourless, and the mixture becomes of an intense blue, colour." Add''again5 * HUle sulphuric acid aWd tJie,"ColrJar'disappears, which, is again restored l>y a little sdhnUott of cadsticam

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DESCRIPTIVE HISTORY OF THE STEAM-ENGINE.

{Concluded.) After Savery's engine became known, a great deal more attention was directed to the subject than before; and the names even of those who were successful in their attempts to improve it, would occupy no inconsiderable space. In Savery's engine, "the effect is produced by the condensation of the steam forming a vacuum in a receiver, into which the water is forced by the pressure of the atmosphere; and where the water was required to be elevated to a greater height than from 28 to 30 feet, he employed the direct pressure of steam .of a high pressure und dangerous elasticity." It could only,

however, be applied with safety to raise water ahout 30 feet. A very short time after the publication of Savery's book, ThomasNewcomen, a blacksmith, and John Cawley, a glazier, both living in the town of Dartmouth, in Devonshire, •' made the experiment of introducing steam under a piston moving in a cylinder, and formed a vacuum by condensing the steam by an effusion of cold water on the outside ofthe steam vessel, and the weight of the atmosphere pressed the piston to the bottom of the cylinder. This was the first form of the atmospheric engine, the simplest and most powerful machine that had hitherto been constructed. In the atmospheric engine the process is totally different from that in cooling, or requires to heat it. It has been ascertained that almost every body with which the experiment has been made differs from every other in this respect, and therefore all bodies have a specific caloric which may be expressed with relation to water. The other terms have all been applied to this difference of capacity in bodies for heat, but specific caloric is now the' phrase most generally adopted.

Calorimeter. An instrument for measuring the heat given out by a body in cooling; both ice and water are employed, and the latter is now preferred, but originally the first alone was used.

Caheleon Mineral. A curious substance, so named from the changes which take place in its colour, and formed by fusing an alkali with black oxide of manganese.

Cahpeachy Wood, logwood, A well-known dye.

Camphor. A white concrete substance, resembling spermaceti in appearance, but having a strong, lively, acrid taste. It is obtained from the roots, wood, and leaves of two species of laurel which grow in the eastern part of the world. It is used ehieQy in medicine. •

Camphorates. Salts composed of camphoric acid and a base, of which nothing is known.

Camphoric Acid. A peculiar acid obtained from camphor.

Cannon Metal. An alloy of 100 parts copper and 10 or 12 of tin.

Cantharidin. A name given to the peculiar substance extracted from cantharides, or Spanish flies, which excites blisters when applied to the skin. i Caoutchouc, India rubber. Elastic gum. Is the dried juice of some plants, such as the jatropa elaitica, which grow in hot climates. It is a very useful substance, and from the late improvements in the management of it, promises to be of' still greater service in the arts.

Mineral. A sub-'

stance resembling India rubber, found in Derbyshire.

! Carbon, pure oMrcoat. An elementary substance.

POTATOES A SUBSTITUTE FOR SOAP.

It is stated in the Bulletin Technologique, that potatoes, fhreefourths boiled, employed instead of soap, are more efficacious than it in cleansing clothes of all descriptions. They are used as soap, and the clothes are otherwise washed in the -same manner, though without employing any alkali. This will, however, be of little use in England, where washing by steam is growing fashionable. By the bye, we wonder the washerwomen of the kingdom have not united to petition Parliament against the new Steam-washing Company. Were this laudable body properly represented in parliament, the trade of the wash-tub could not be thus injured with impunity. We are afraid our publication is not much studied by them; but if the Economist were under our direction, we should certainly rouse these much-injured women to take care of their own interest.

TO CORRESPONDENTS.

We are glad to see the hand-writing again of our friend The Chemist, and congratulate him on his return. . .

Mr. Thompson is informed, that tre know of no book like the one he mentions; and that; in no treatise on distillation, with which we, are acquainted, is any thing said of the.subject onahkh he requires information. , Hewitt find some observations in alt chemical treatises, but there is no separate work on this particular branch. He should, however, rather apply to his own bookseller than to us. '.....

%* Communications (post paid) to be addressed to the Editor, at the Publishers'.

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