Page images
[ocr errors]






[ocr errors]



[ocr errors]
[ocr errors]

emp.oyed in exploding the wires mentioned, the which consists of sulphur and mercury, the merlength of each wire being ten inches: the coated cury will be separated with such ease as that the surface was the same in all the experiments, viz. charge of a moderately sized jar will be found one of his batteries of fifteen jars, exposing quite sufficient. seventeen feet of coated surface. The column

DecoMPOSITION OF WATER BY ELECTRICITY. marked A, shows the diameter of the wires in parts of an inch; B the number of grains with 243. The decomposition of water by electriwhich the electrometer was loaded; and C the city was first effected by Van Troostwyk and color of the oxide deposited on the receiver : Deiman, assisted by Mr. Cuthbertson ; this they


effected by means of a complicated apparatus, Lead wire

Light gray:

and a very tedious process. Their method of Tin wire ot 30 Nearly white.

procedure was improved on by Dr. Pearson, Zinc wire 45 Nearly white.

and after him by Mr. Cuthbertson: but the most Iron wire Ibo

Reddish brown. simple form of an apparatus for this purpose is Copper wire 35 Purple brown.

that of Dr. Wollaston. This apparatus is thus Platina wire 35 Black.

constructed :—Two finely pointed wires of gold Silver wire ibo 40 Black.

or platina are inserted into capillary tubes ; each Gold wire 150 40 Brownish purple

wire is thrust into the tube till it nearly reaches 238. Mr. Singer was of opinion that the the end of it, and the glass is softened by heat charges here given by Mr. Cuthbertson were The glass is then carefully ground away, till the

until it adheres to the wire and covers its point. rather high, and attended with considerable risk of fracture to the jars : he repeated the experi- point of the wire can be seen by the help of a ments with shorter lengths of wire, and of less magnifying glass. One of these wires is made to diameter; and with more moderate charges tive conductor of the machine, and the other

communicate with the ground, or with the negaobtained the following results :

with an insulated ball placed near the positive A. B. C.

conductor, the two points are placed near each Gold wire ito 18 Purple and brown.

other in a vessel of water; when a current of Silver wire to 18 Gray, brown, and green. sparks is discharged through the wires, a series Platina wire ido 13 Gray and light brown. of minute bubbles of gas will rise from the points Copper wire 12 Green, yellow, and brown. of the gold wires, and, when collected in an Iron wire ISO 12 Light brown.

inverted receiver, will explode on the application Tin wire to 11 Yellow and gray.

of a lighted taper. Dr. Wollaston found by Zinc wire 180 17 Dark brown.

experiment, that a point qdo of an inch in diaLead wire to 10 Brown and blue gray. meter, decomposed the water when the spark Brass wirė . Ito 12 Purple and brown. which passed from the conductor to the insulated

239. In the above experiments Mr. Singer ball was f of an inch in length; and that a point did not use the receiver; the wires, which were too of an inch in diameter, produced the same five inches in length, were stretched parallel to effect when the sparks were only at of an inch the surface of a sheet of paper, and distant from in length. Hence the rapidity of the decomit about one-eighth of an inch. Brass wire is position was in proportion to the limited size of sometimes decomposed by the electrical charge, the point of the wire. in which case its component parts, copper and 244. Of the results obtained in sonie experizinc, are separated from each other, and appear ments made with this apparatus, Dr. Wollaston in their distinct metallic colors when the explo- gives the following account. By transmitting a sion is made over a piece of glass. Indeed the current of sparks by means of two gold points figures of all the oxides are most beautiful when over the surface of a card a little moistened, and impressed on glass, although their colors are tinged with litmus, and placed between the certainly less permanent.

points, a redness was perceived about the positive 240. This most amazing power of the electric wire after a few turns of the machine. When the matter is not only adequate to the oxidation of negative wire was placed upon the red spot it metallic substances, but is yet more remarkable was quickly restored to its former color. Hence in restoring oxides, alrcady formed, to their he infers that the effect of an acid is produced at metallic, or original state, for which purpose a the positive wire; and that this effect is countervery simple process will be found sufficient.

acted by reversing its electricity. 241. Into a small glass tube introduce a little 245. Dr. Wollaston next coated two wires of the oxide of tin; let it cover about half an with sealing-wax, so that their ends only were inch of the lower internal surface. Place the exposed : these he inserted into a solution of tube thus prepared on the table of Henley's copper, and found that, on transmitting a current discharger, and introduce the pointed wires at of sparks between them, the negative wire was each end, that the oxide may form part of the coated with copper :* the electricity of the wire circuit. Pass now several strong charges in suc- being reversed, the copper quickly disappeared cession through the tube, taking care to replace 246. When it is wished to decompose oils, the oxide in its proper situation, should it be alcohol, ether, &c., a much more simple, and less dispersed. If the charges are strong, the tube expensive apparatus will be found to answer will soon become stained with the tin revived every purpose. This apparatus, which is reprefrom the oxide.

sented by fig. 8, consists of a glass tube having a 242. In the same way other metallic oxides platina wire projecting from the top in wards and may he revived; but if vermilion be employed, reaching nearly to the lower end. The lower

extremity is open, and is placed in a metallic stúp-cock. When the cocks are opened, the dish nearly filled with the fluid which is to be globe will be filled with the gases; they must decomposed. The cylinder must be filled with then be shut, and a spark passed from the wire the fluid as receivers are filled with water in the in the inside of the globe to the cap. A bright pneumatic trough. When charges are succes- flash follows, and the inside of the globe becomes sively sent through the wire, the fluid will be covered with moisture; the cocks are then to be gradually decomposed, and the gaseous product opened, and more gas will rush into the globe. rising to the upper part of the cylinder will dis- The cocks being again closed, a second explosion place the liquid. In all experiments of this kind may be made, which will increase the dew on the glass used ought to be very strong to resist the inside of the globe ; and the experiment may the expansion caused by the explosion.

be repeated in this way until drops of water may 247. Flaving spoken of the decomposition of be observed. water by means of the electric fluid, it may be pro 248. Such experiments as the preceding per just to notice the process of forming water naturally led to numerous others on various from the gases that compose it, hy the action of liquids and also on different gaseous bodies : to the same agency. For this curious experiment detail these would be foreign to our purpose; Mr. Singer employed the apparatus represented yet to pass them over in silence would be to do in fig. 9, which consists of a stout globe of glass, them injustice. We shall, therefore, merely give with a stop-cock, having a wire passing through the results of some remarkably fine experiments its centre to within a short distance of the cap to by Cavendish, and others, as drawn up in a which the stop-cock is screwed. The globe must tabular form by Mr. Singer. The numbers prebe exhausted by means of an air-pump, and then fixed to some of the gases indicate the proporscrewed on a receiver containing a mixture of tionate measures employed of each. oxygen and hydrogen gases, furnished with a MIXED GASES.

Atinospheric air and hydrogen

Water and nitrogen.
Oxygen and hydrogen

Chlorine and hydrogen

Muriatic acid.
Muriatic acid and oxygen

Carbonic oxide and oxygen

Carbonic acid.
Nitrogen and oxygen

Nitric acid.
Sulphurous acid and oxygen

Sulphuric acid.
Phosphureted hydrogen and oxygen

Water and phosphoric acid.
Sulphureted hydrogen and oxygen

Water and sulphurous acid.
Oxygen and ammonia

Water and nitrogen.*
100 olefiant gas and 284 oxygen

Carbonic acid and water. 100 olefiant gas and 100 oxygen

Carbonic oxide and hydrogen. 100 carbureted hydrogen and 100 oxygen

Carbonic oxide and hydrogen.
100 carbureted hydrogen and 200 oxygen

Carbonic acid.

Muriatic acid

Fluoric acid

Nitrous gas

Nitric acid and nitrogen.
Carbonic acid

Carbonic oxide and oxygen.
Sulphureted hydrogen

Sulphur and hydrogen.
Phosphureted hydrogen

Phosphorus and hydrogen.

Hydrogen and nitrogen.
Olefiant gas

Charcoal and hydrogen.
Carbureted hydrogen

Charcoal and hydrogen. The results marked with a star are given on fessor Lichtenberg, of Gottingen, and afterwards the authority of Dr. Henry and Mr. Dalton. In by Mr. Bennet, Cavallo, and others. making the above experiments when the mixture 250. Excite a plate of any resinous substance, consisted of inflammable gases with oxygen, the as gum-lac, by friction, and let any metallic body change was usually effected by a single spark; of any shape whatever, a brass ting for instance, but in other cases it was found necessary to con- be placed upon the plate. Let the ring be then tique the current of sparks for many hours. electrified with an electricity opposite to that of ELECTRICAL CONFIGURATIONS.

the plate, and afterwarıls removed from the plate

by a stick of sealing-wax, or any other non-con249. This is a most interesting and curious ductor. Let some powdered resin be now shaken branch of mechanical electricity, and one which upon the plate, then if the plate has been excited certainly challenges a more vigorous enquiry than negatively, and the brass ring positively, the has hitherto been made respecting it. It is thought powder will fall only on those points of the plate by some that the experiments which we shall here that were touched hy the ring, and will form briefly notice afford satisfactory proof that elec- radiating appearances resembling stars, while tricity is the real cause of crystallisation. The almost no powder will be found on any other subject seems to have been first noticed by pro- part of the plate. If, on the other hand, the



pate has been electrified positively, while the piece in the same manner, again pouring on more ring was electrified negatively, the powdered water, and thus proceed till all the pieces are resin will fali only on the parts of the plate laid in. By using hot water, the paper will be which were formerly uncovered, the figures being softened in a few min'ites. now indicated by the absence of the powder.. 255. When the figures aru to be made, the

251. Mr. Bennet who repeated with much resinous plate must lie horizontally, whilst the care the experiments of Lichtenberg, has given the electricity is communicated, if the experiment following account of the method wliich he adopted requires any thing to be placed upon the plate: for rendering figures produced in this way per- but it is convenient afterwards to place it in a manent. When it is wished to make the figures vertical position whilst the powder is projected, red, “ Take a pound of rasped Brasil wood; put lest too much powder should fall where it is not it into a kettle with as much water as will cover required. it, or rather more: also put in about an ounce of 256. “A little of the powder may be taken gum arabic, and a piece of alum about the size of between a finger and thumb, and projected by a large nut; let it boil about two hours, or till drawing it over a brush; or, what is better, a the water be strongly colored; strain off the ex- quantity of it may be put into the bellows and tract into a broad dish, and sét it in an iron oven, blown towards the plate. When the figure is where it is to remain till all the water be evapo- sufficiently covered with powder, let the plate rated, which with me was effected in about twelve be again laid horizontally upon a table; then hours; but this depends on the heat of the oven, take one of the softened papers out of the water which should not be so hot as to endanger its by its dry edge, and lay it carefully between the burning. Sometimes I have boiled the strained leaves of a book, pressing the book together, and extract till it was considerably inspissated before permitting it to lie in this situation about half a it was placed in the oven, that it might be minute. Then remove the paper to a dry place sooner dry.

in the book, and press it again about the same 252.. When it is quite dry, but not burnt, time, which will generally be sufficient to take scrape it out of the dish, and grind it in a mor off the superfluous moisture. Then take up the tar till it be finely pulverised. In doing this, paper by the two corners of its dry edge, and it is proper to cover the mortar with a cloth, place the wet edge a little beyond the figure on having a hole through it for the pestle, to prevent the resinous plate, lowering

the rest of the piece the powder from flying away and offending the gradually till it covers the figure without sliding; nose, and also to do it out of doors if the weather then lay over it a piece of clean dry paper, and be dry and calm, that the air may carry away the press it gently; let it remain a short time, and powder necessarily escaping, and which other- then rub it closer to the plate with a cloth; or, wise is very disagreeable. When ground, let which is better, press it down by' means of a it be sifted through a fine hair sieve, returning wooden roller covered with cloth, taking care the coarser part into the mortar to be ground that the paper be not moved from its first posiagain.

tion. 253. “ The plate I have mostly used, was com 257. • When the paper is sufficiently pressed, posed of five pounds of resin, half a pound of let it be taken up by its dry edge, and laid upon bees'-wax, and two ounces of lamp-black, melted the surface of a vessel of water, with the printed together, and poured upon a board sixteen inches side downwards; by this means the superfluous square, edged round with slips of wood, at least powder will sink in the water, and the figure will half an inch high, to confine the composition not be so liable afterwards to spread on the whilst fluid : the plate was thus half an inch paper. After the paper has remained on the thick, which is better than a thinner plate, the water a few minutes, take it up and place it befigures being more distinct. After the compo- tween the leaves of a book, removing it fresition is cold, it will be found covered with quently to a dry place. If it be desired that the small blisters, which may be taken out by hold- paper should be speedily dry, let the booking the plate before the fire till the surface be a leaves in which it is to be placed be previously little melted, then let it cool again; and upon warmed, and by removing it to several places it holding it a second time to the fire, more blis- will be dry much sooner than by holding it near ters will appear; but by thus repeatedly heating a fire. By the above process, it is obvious that and cooling the surface, it will at last become leather, calico, or linen, as well as paper, may perfectly smooth. Some plates were made be printed with these figures, and the effects of smaller, and the resinous composition confined the diffusion of electricity upon a resinous plate to the form of an ellipsis, a circle, or escutcheon, be exhibited to those who have not leisure or by a rim of tin half an inch broad, and fixed inclination to perform the experiments.'

258. To the above it may be proper to add, : 254. ' The next thing to be done is to prepare that with a resinous plate of the kind now dethe

paper, which is to be softened in water, either scribed, a very beautiful exhibition may be made by laying the pieces upon each other in a vessel of the different powers of positive and negative of cold water, or first pouring a little hot water electricity. For this purpose prepare equal upon the bottom of a large dish; then laying quantities of red lead and resin, by weight, upon it a piece of paper, so that one edge of the finely powdered and intimately mixed, by being paper may lie over the edge of the dish, to re- sifted together through a fine hair sieve. Put this main dry, that it may afterwards be more con powder into a bottle of India rubber for use. veniently taken up. Then pour more hot water Let now a small jar be charged at the positive upon its upper surface. Upon this place another conductor of the machine, and, with its knob,

upon a board.

quickly write the letter P on the resinous plate: pole in any case, even when the bar had previo take the bottle containing the mixed powders, ously some magnetism, and was placed wit, the and by gently striking the sides of it between south pole downwards. Things remaining the the palms of the hands, the mouth of it being same, the bars seemed to acquire an equal degree directed towards the plate, which must be placed of magnetic power, whether they were struck in a vertical position, project on the electrified whilst standing horizontally in the magnetic part a little of the powder, and the letter will meridian, or perpendicular to the horizon. instantly appear, well defined, and covered with When the needle was placed in the magnetic the red lead, while the resin will be dispersed. equator, whichever way the charge entered, it Ii now the whole be wiped clean off, and, with a never produced any inagnetism; but if it was jar charged at the negative conductor, the letter passed through its width, then the needle N be written on the plate, and the powder pro- acquired a considerable degree of magnetism, jected as before, it will be found that the nega- and the end which lay towards the west became tive electricity has selected the resinous particles the north pole, and the other end the south pole. for the formation of the letter, while those of If a needle or bar, already magnetic, or a real the red lead have been rejected.

magnet, was struck in any direction, its power

was always diminished. For this experiinent MAGNETIC EFFECTS OF ELECTRICITY.

they used considerably large bars, one of which 259. The connexion between magnetism ana was 7.08 inches long, 0·26 broad, and 0:05 thick. electricity will be fully treated of in a subse- When the shock was so strong in proportion to quent part of this article; at present we shall the size of the needle, as to render it hot, then merely offer the following general remarks in the needle generally acquired no magnetism at the way of showing the amount of what was all, or very little. These experiments were made known on the subject previously to the interest- with the power of a battery composed of 135 ing discoveries recently made.

phials, containing among them about 130 square 260. Dr. Franklin appears to have been the feet of coated surface. first who paid any serious attention to this suh

Medical ELECTRICITY. ject. He sent the charge of some large electrical jars through fine sewing-needles; the ends of 263. The very remarkable properties of the the needles were rendered blue, and on being electric fluid seem to have occasioned the applicarefully laid on water they traversed, evincing cation of its powers to organised bodies at an evident proofs of polarity. The most remark- early period of its history; and the results, able circumstance attending these experiments whether real or imaginary, gave rise to various was, that if the needle lay east and west when opinions, which are now only viewed as monuthe charge was passed through it, the end which ments of credulity and imposture. It is not our was entered by the fluid pointed to the north : intention to enter here minutely into an investibut if it lay south and north, the end which lay gation of this department of the science of elecpointing to the north would continue to do so, tricity; yet, although this would be improper on whether the charge entered by that end or the several grounds, we must not pass it over in other; although the Dr. imagined that a still silence. The application of electricity as a stronger charge would have reversed the poles, medical agent has recently been much revived; even in that situation, since this effect had been but that application is, we believe, most successactually produced by lightning. The polarity fully made in the form of Voltaic electricity; he also found to be strongest when the needle and will therefore fall, with more propriety, received the charge while lying north and south, under consideration in another place. From the and weakest when it lay so as to point east and numerous respectable testimonies extant, as to

the real utility of electricity in the healing art, 261. But the experiments most to be relied we shall inake a choice selection, which it is on were made by Van Marum with the large hoped will satisfy the reader, that in the hands machine and battery in the Tylerian museum at of a skilful operator, it may be applied in numeHaarlem. He and his assistants tried to give rous instances with certainty of success. Let it polarity to needles made of watch-springs, of however be observed that no one ought to attempt from three to six inches in length; and also to its application who is not thoroughly conversant steel bars nine inches long, from a quarter of an with the use of the apparatus, and capable of inch to half an inch broad, and about a line in forming a correct judgment, as to the strength thickness. The result was, that when the bar and duration of the application. was placed horizontally in the magnetic meridian, 264. Speaking of the power of the apparatus whichever way the shock entered, the end of it which ought to be used in the application of that stood toward the north acquired the north electricity for medical purposes, Mr. Singer polarity, and the opposite end acquired the justly remarks, that the machine employed ought south. If the bar, before it received the shock, to be such as will furnish a constant stream of had some polarity. and was placed with its poles sparks ; if a plate machine, it ought to be two contrary to the usuai direction, its natural polar- feet in diameter; if a cylinder machine, not less ity was uniformly diminished, and often reversed; than ten inches, and fourteen if possible. Ma80 that the extremity of it, which in receiving chines called medical electrical machines, are the shock pointed to the north, became the north sometimes made on a very small scale, and hence pole, &c.

the application of them only produces trouble, 262. When the bar was struck standing per- waste of time, and final disappointment. pendicularly, its lowest end became the north 265. In connexion with a powerful electrical


machine, the auxiliary apparatus requisite for afford relief; and about one in five are permamedical purposes are the following :-A jar nently cured. 8. Opacity of the cornea. This fitted up with Lane's electrometer, by which is sometimes cured by the long continued action shocks may be given of any required force. A of electricity thrown for ten minutes a day or the pair of directors, each consisting of a glass han- eye hy a wooden point. When caused by the dle, surmounted by a brass cap with a wire of a small-pox, it is said to yield most readily. 9 few inches in length, having a ball screwed on its Gutta serena. The method of electrifying for extremity, which may be occasionally unscrewed opacity of the cornea has been successful in and a wooden point substituted for it. When some instances of gutta serena; but there are shocks are given by means of these directors, numerous unsuccessful cases. 10. Amenorrhæa they must be applied at the opposite extremities Cases of suppressed menstruation are generally of the part through which the charge is required relieved by sparks and slight shocks; hut in reto pass; and being respectively connected by tention of the menses electricity has been tried conducting wires, the one with the outside of the without success. 11. Knee cases. In instances jar and the other with the receiving ball of the of pain and swelling of the knee, the applicaelectrometer previously placed at the requisite tion of sparks has been effectual in about one distance, the jar may be set to the machine, case in ten. 12. Chronic rheumatism. Very which is then put in motion until any required numerous are the instances of success; the number of shocks has been given.

usual application is by sparks, for ten or fifteen 266. The insulated director is also employed minutes every day. In recent cases, a few days to give sparks, being held by its glass handle, is sometimes sufficient; but in those of long and its ball previously connected with the con- standing, very considerable perseverance is often ductor by a fine chain being brought near the required. 13. Acute rheumatism. In one case patient, or rubhed lightly over a piece of flan- oui of six a cure was effected in about a month nel or woollen cloth laid on the affected part. hy the application of electricity. 14. Palsy. When the cye or any delicate organ is electrified, Moderate shocks, with sparks, have been occathe ball of the insulated director is unscrewed sionally successful in about one case of paralysis and the wooden point applied, at the distance in every fourteen that have been tried. 15. St. of about half an inch from the part. The stream Vitus's dance has been frequently relieved by of electricity which passes from the point, in such electricity. There are indeed scarcely but few cases, produces rather a pleasant sensation than diseases in wbich some successful instances of otherwise.

its application are not recorded; but we are still 267. An insulated stool is sometimes em- in want of a scientific examination of the stateployed; it should be of sufficient size to receive ments that have been made on this subject. a chair upon it, with a resting place in front of 269. It appears that the nerves are most powthe chair for the feet. The patient being placed erfully affected by electricity, since the effect of on the insulated chair, and connected with the a discharge sent through the body is always conductor of the machine by means of a chain, most conspicuous in their direction. When the sparks may be drawn from any part of the body charge of a battery is sent through the head of a by a person who stands on the ground and pre- bird, the optic nerve is generally found to be sents a brass ball to it.

injured, and often completely destroyed; a like 268. The following ennuncration of instances discharge sent through a larger animal is found of disease in which electricity has been success to produce a universal protraction of strength, fully applied, is given by Mr. Singer as esta- with trennbling and depression. Mr. Singer says blished on gond authority :- 1. Contractions. he once accidentally received a considerable Those only that depend on the affection of a charge from a battery, through the head, which nerve; and in many of these it has been em- produced the sensation of a violent but universal ployed without effect, whilst in others of long du- hlow, followed by a transient loss of memory ration immediate relief has been obtained. 2. and indistinctness of vision, but was unattended Rigidity. Very frequently relieved, but usually by any permanent injury. requiring some perseverance in the application, 270. Mr. Morgan, who paid considerable atto complete the cure. 3. Sprains, relaxation, tention to medical electricity, has remarked, that &c. Electricity may be applied in all these if the diaphragm be made to form part of the cases with good effect, but its application should circuit of a coated surface equal to two feet, be deferred until the inflammation has subsided. fully charged, the lungs make a sudden effort, 4. Indolent tumors. Strong sparks, and slight which is followed by a loud shout; but that if shocks, are often effectnal. The most numerous the charge be small, it never fails to produce a cases are those of scirrhous testicle; and there violent fit of laughter; and that even those are some instances of the successful dispersion whose calmness and solemnity are not easily of scirrhous induration of the breast. 5. Mr. disturbed by ludicrous occurrences, are seldom Carpne states, that electricity is a good preven- able to withstand the powers of electricity. tive against chilhlains; and mentions iwo in- The first effect of a strong charge on the dia stances in which they were removed by the phragm is frequently followed by involuntary action of electrical sparks. 6. Epilepsy. In sighs and tears, and sometimes by a fainting fit. several instances of persevering application, not If the charge be passed through the spine, it one successful case occurred. 7. Deafness. produces a degree of weakness in the lower exSparks thrown on the mastoid process, and tremities ; so that if a person be standing at the round the meatus auditorius externus, and drawn time, he sometimes drops on his knees, or fails from the same parts on the opposite side, usual y prostrate on the floor.

« PreviousContinue »