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on other sides by low eminences tiun, and lassitude and uneasiness of limestone, or a bituminous in the limbs. Those who are shale, is the immediate situation strongly susceptible to electrical of the springs; they are found in changes in the air, such as prethree or four different places of cede and attend a thunder-storm, the morass, appearing as small will easily understand the effects pools; the sides and bottom of of the Sirocco, as an increased de which are thickly lined with pe- gree of the sensations which they troleum, in a viscid state, and, by then experience; and, in fact, agitation, easily raised in large though I am not aware that the flakes to the surface. The most opinion has been held, there are remarkable of these pools is many reasons for believing that one circular in form, about fifty the peculiarity of the Sirocco wind feet in circumference, and a few is chiefly an electrical one, and feet in depth, in which the petro. not depending either on temperaleum has accumulated to a consi. ture, an undue proportion of carderable quantity. The water of bonic acid, the presence of minute the spring, which is doubtless the particles of sand, or any of the means of conveying the mineral causes which have been generally upwards to the surface, forms a assigned to it. That increased small stream from the pool, sen- temp?rature is not the cause, may sibly impregnated with bitumi- be inferred from the thermometer nous matter, which it deposits in being little, if at all, raised by the parts as it flows through the mo- access of the wind, and from rass; the other pools are of simi. much greater heat often occurring Jar character. The petroleum is without this singularity of effect. collected generally once in the The air of the Sirocco, as it comes year ; and the average quantity from the sea, is not a dry one, obtained from the springs is said but in general thick, and loaded to be about a hundred barrels; it with moisture ; much of which is chiefly used for the caulking of appears to be deposited where it vessels, not being found to answer passes over any considerable exequally well for cordage.

tent of land. I have scarcely, in any instance, observed this wind,

in any marked degree, without THE SIROCCO.

noticing, at the same time, some

electrical phenomena in connec(From the Same.)

tion with it ; to say nothing of

the effects upon the body, which, A sudden and violent Sirocco as mere sensations, may perhaps came on from the south-east, car- be doubtfully received in evidence. rying our vessel forwards eight or in the present instance, off the ten miles an hour ; but bringing coast of Ithaca, the sky, which with it, at the same time, all the had been obscured by the approach distressing effects which charac- of evening, was suddenly kindled, terize this extraordinary wind; a as the wind came on, by broad sense of general oppression, & Aashes or gleams of electric light, dull head-ache, aversion to mo- which seemed to prevade the whole

2 K 2

hemisphere, hemisphere, and, at intervals, shifting rapidly among the broken were so bright as to allow the intervals of the clouds, and near reading of the smallest print. At the horizon, assuming at times the same time I observed a mass the appearance of a chain of light, of clouds gathering in the north- which

seemed to pass from a higher west, the quarter to which the to a lower surface of cloud, and wind was blowing, and here the often continued to the eye for two electrical appearances became pe- or three seconds. culiarly vivid, flashes of light

USEFUL

USEFUL PROJECTS, &c.

THE

Sir Humphrey Davy's Discovery of It is evident, then, that to prevent

a Method for preventing Explo- explosions in coal mines, it is only sions from the Fire Damp in necessary to use air-tight lanterns, Mines.

supplied with air from tubes or

canals of small diameter, or from THE numerous fatal effects of apertures covered with wire gauze

explosions in the collieries placed below the flame, through which have lately engaged the which explosions cannot be compublic attention, having induced municated, and having a chimthe eminent chemical philosopher ney at the upper part, on a siabove-mentioned to turn his stu- milar system for carrying off the dies to the subject, the result has foul air ; and common lanterns been a very curious and valuable may be easily adapted to the purpaper communicated to the Royal pose, by being made air-tight in Society, and printed in their the door and sides, by being Transactions for 1815, from furnished with the chimney, and which the following extract, chief- the system of safety apertures bem ly referring to the practical part, low and above. has been made.

The principle being known, it After ascertaining, by a variety is easy to adopt and multiply pracof experiments, the combustibi. tical applications of it. lity and explosive nature of the The first safe-lantern that I had fire-damp in mines, and finding constructed was made of tin-plate, that a mixture of this gas with and the light emitted through four air would not explode in metallic glass plates in the sides. The air canals or troughs when their dia. was admitted round the bottom of meter was less than one-seventh the flame from a number of meof an inch, and that explosions tallic tubes of j of an inch in diawould not pass through such ca- meter, and an inch and į long.nals; also that explosions would The chimney was composed of not pass through very fine wire two open cones, having a comsieves or wire gauze ; Sir H. D. mon base perforated with many comes to the following inference. small apertures, and fastened to

the

the top of the lantern, which was of air and one of gas from the made tight in a pneumatic rim distillation of coal, suffered it to containing a little oil; the upper burn out in the vessel, and then and lower apertures in the chim- analysed the gas. After the carney were about of an inch: the bonic acid was separated, it aplamp, which was fed with oil, peared by the test of nitrous gas gave a steady flame of about an to contain nearly of its original inch high, and half an inch in dia- quantity of oxygen ; but detonameter. When the lantern was tion with a mixture of equal parts slowly moved, the lamp continued of hydrogen and oxygen proved to burn, but more feebly; and that it contained no sensible quanwhen it was rapidly moved, it tity of carburetted hydrogen went out. To obviate this cir- gas. cumstance, I surrounded the bot. It is evident, then, that when tom of the lantern with a perfo- in the safe-lantern the air gradurated rim ; and this arrangement ally becomes contaminated with perfectly answered the end pro- fire-damp, this fire-damp will posed.

be consumed in the body of the I had another chimney fitted lantern; and that the air passing to this lantern, furnished with a through the chimney cannot connumber of safety tin-plate tubes tain any inflammable mixture." of the sixth of an inch in diame- I made a direct experiment on ter and two inches long ; but they this point. I gradually threw an diminished considerably the size explosive mixture of fire-damp of the flame, and rendered it more and air into the safe-lantern from liable to go out by motion; and a bladder furnished with a tube the following experiments appear which opened by a large aperture to show, that if the diameter of above the flame; the flame bethe upper orifice of the chimney came enlarged, and by a rapid jet be not very large, it is scarcely of gas I produced an explosion in possible that any explosion pro- the body of the lantern; there duced by the flame can reach it. was not even a current of air

I threw into the safe-lantern through the safety tubes at the with the common chimney, a mix- moment, and the flame did not ture of 15 parts of air and one of appear to reach above the lower fire-damp; the flame was imme- aperture of the chimney; and the diately greatly enlarged, and the explosion merely threw out from flame of the wick seemed to be it a gust of foul air. lost in the larger flame of the fire- The second safety-lantern that damp. I placed a lighted taper I have had made is upon the same above the orifice of the chimney: principle as the first, except that it was immediately extinguished, instead of tubes, safety canals are but without the slightest previous used, which consist of close conincrease of its flame, and even centric hollow metallic cylinders the wick instantly lost its fire by of different diameters, and placed being plunged into the chimney. together so as to form circular ca

I introduced a lighted taper into nals of the diameter of from is to a close vessel containing 15 parts of an inch, and an inch and to

long,

long, by which air is admitted in the air canals, from the explosive much larger quantities than by the atmosphere, the light was unismall tubes. In this arrangement formly extinguished; and when there is so free a circulation of an explosive mixture was forcibly air, that the chimney likewise may pressed into the body of the lamp, be furnished with safety canals. the explosion was always stopped

I have had lamps made for this by the safety apertures, which may kind of lantern which stand on be said figuratively to act as a sort the outside, and which may be of chemical fire sieves in separating supplied with oil and cotton with flame from air. out any necessity of opening the When the fire-damp is so mixed lantern ; and in this case the chim- with the external atmosphere as ney is soldered to the top, and the to render it explosive, the light in lamp is screwed into the bottom, the safe-lantern or lamp will be and the wick rises above the 'air extinguished, and warning will be canals.

given to the miners to withdraw I have likewise had glass lamps from, and to ventilate that part of with a single wick, and Argand the mine. lamps made on the same principle, If it be necessary to be in a part the chimney being of glass cover- of the mine where the fire-damp ed with a metallic top containing is explosive, for the purpose of the safety canals, and the air en- clearing the workings, taking away tering close to the flame through pillars of coal, or other objects, the circular canals.

the workmen may be lighted by a The third kind of safe lamp or fire made of charcoal, which burns lantern, and which is by far the without flame, or by the steel-mill, most simple, is a close lamp or though this does not afford such lantern into which the air is ad- entire security from danger as the mitted, and from which it passes, charcoal fire. through apertures covered with It is probable, that when explobrass wire gauze of zoo of an inch sions occur from the sparks from in thickness, the apertures of the steel-mill, the mixture of the which should not be more than fire-damp is in the proportion reTio of an inch ; this stops explo- quired to consume all the oxygen sions as well as long tubes or ca- of the air, for it is only in about nals, and yet admits of a free this proportion that explosive mixdraught of air.

tures can be fired by electrical Having succeeded in the con- sparks from a common machine. struction of safe-lanterns and As the wick may be moved withlamps equally portable with come out communication between the mon lanterns and lamps, which air in the safe-lantern or lamp afforded sufficient light, and which and the atmosphere, there is no bore motion perfectly well, I sub- danger in trimming or feeding mitted them individually to prac- thenı ; but they should be lighted tical tests, by throwing into them in a part of the mine where there explosive atmospheres of fire- is no fire-damp, and by a person damp and air. By the naturalaction charged with the care of the lights; of the flame drawing air through and by these inventions, used with

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