The Progress of Invention in the Nineteenth Century Part 23

This new kind of light ray was discovered November 8, 1895, by Prof. W.

C. Roentgen, of the Royal University of Wurzburg, and was named by him the "X-Ray," probably because the letter x in algebraic formula represents the unknown quant.i.ty, and the hitherto unknown and elusive quality of this light suggested to Prof. Roentgen this appropriate name.

As before stated, a peculiar quality of the X-Rays is that they are not visible to the eye. A beam of X-Rays, thrown into a dark chamber through an aluminum window, would produce no illumination whatever in the room, but such rays would still penetrate the room, and if a fluorescing screen were placed in their path it would instantly light up. It is not surprising, therefore, that these subtle rays should have so long eluded the observation of the scientist.

A brief sketch of the conditions leading up to the discovery of the rays is necessary to a proper understanding of the same.

[Ill.u.s.tration: FIG. 215.--THE CATHODE RAY.]

Every student of physics remembers the old-time lecture room experiments in which the Geissler tubes, with their beautiful play of colored lights, ill.u.s.trated the action of the electrical discharge from the gla.s.s plate machine or the Ruhmkorff coil, on rarified gaseous media. Electrical experiments in high vacua by Sir William Crookes, and by Hittorf and Lenard, have greatly added to the present knowledge in this field, and paved the way to the discovery of Prof. Roentgen. It was known that a vacuum tube, variously called after the names of these scientists, as a Crookes, Hittorf, or Lenard tube, having platinum electrodes sealed in its ends, would, under the static discharge of electricity through it, give peculiar manifestations of light. One of the conducting terminals of such tubes was called, in electrical parlance, the "anode," from the Greek a?a (up) ?d?? (way), meaning the way up or into the tube, and referring to the entering path of an electric current, or its positive pole; while the other was called the "cathode," from ?ata (down), ?d?? (way), meaning the way down or out, and referring to the outgoing path of an electric current, or its negative pole. When such gla.s.s tube, partially exhausted of air, received through its anode and cathode terminals a discharge of static electricity, a peculiar manifestation of light is seen between the anode and cathode terminals. At the anode it appears as a peach blossom glow, and at the cathode it appears as a bluish green light. If the exhaustion of the air in the tube is carried very high, approaching a perfect vacuum, or to about one millionth of the atmospheric pressure, the glow light at the anode disappears, and that at the cathode increases until it fills the entire tube with its characteristic light. This is called the "cathode ray," or "cathodic ray," an ill.u.s.tration of which is given in Fig. 215, where the cathode ray is seen in a Crookes tube emanating from the negative pole N or cathode _a_, and casting a shadow of the Maltese cross _b_ into the end of the tube, as seen at _d_. Many of the characteristics of the cathode ray had been observed prior to Prof.

Roentgen's discovery, which, briefly stated, grew out of the following observation: He noticed that when a vacuum tube illumined by the cathode ray was completely masked or covered up by an external s.h.i.+eld of black paper, so that no illumination of the tube was visible to the eye, there still pa.s.sed through it certain subtle rays of light, invisible to the eye, but which would instantly illuminate a sheet of paper coated on one side with barium platino-cyanide, even at a distance of two yards or more, and that these invisible light rays were capable of pa.s.sing through many substances opaque to ordinary light. He also discovered that these rays could be made to take a shadow photograph on a sensitive plate without even exposing the plate in the usual way, the X-Rays pa.s.sing freely through the opaque ebonite or pasteboard screen of the plate holder. It did not take the scientific world long to realize the immense importance of this discovery, and to-day X-Ray apparatus const.i.tutes the greatest addition to the surgeon's resources that has ever been made in the form of mechanical appliances, since by its aid any foreign body in the human frame of greater density than the flesh may be at once definitely located and extracted, or any fracture of the bone disclosed, as the case may be. In the ill.u.s.tration, Fig. 216, is shown an X-Ray photograph of the hand of a gentleman whose thumb bone has been destroyed by disease.

[Ill.u.s.tration: FIG. 216.--X-RAY PHOTO OF HAND, SHOWING DISEASED THUMB BONE.]

Soon after the announcement of Prof. Roentgen's discovery, apparatus was devised for seeing with the naked eye the image formed by the shadow of the X-Rays. Prof. Salvioni constructed such a device and described it before the Rome Medical Society as early as February 8, 1896. He called it the "cryptoscope." It was quite a simple affair, and consisted of an observation tube with a lens, having in front of it a screen of fluorescing material, such as platino-cyanide of barium. When the object to be examined, the hand, for instance, was held in front of the fluorescing screen, and the X-Rays from the vacuum tube fell upon the hand, located between the vacuum tube and the fluorescing screen, a shadow of the bones was cast on the fluorescing screen by virtue of the greater density of the bones, which shadow was clearly discernible to the eye at the end of the observation tube. By this device one was able to see his own bones through the flesh. A device, invented by Edison and called the "fluoroscope," was constructed on substantially the same principle. This used a tapered observation tube like the old-fas.h.i.+oned stereoscope box, which had at its outer wide end the fluorescing screen, and its small end fas.h.i.+oned to fit the forehead and strapped thereto so as to enclose both eyes. This device is shown in Fig. 217, in which an X-Ray vacuum tube is housed in a wooden box, on which the hand of the patient, or other part to be viewed, is laid, the X-Rays pa.s.sing readily through the top of the box and casting a shadow of the bones of the hand, or foreign body, on the fluorescing screen of the observation tube. Edison's experiments also led him in constructing his fluorescing screen, after testing a great number of substances, to select the chemical known as calcium tungstate, instead of the barium platino-cyanide, since the calcium tungstate appeared to give better results in fluorescing. Many other chemicals can be used, however, for making the fluorescing screen, such as the sulphides of calcium, barium and strontium. A recently discovered and powerful fluorescing substance is the double fluoride of ammonium and uranium, discovered by Dr.

Mecklebeke. Such fluorescing materials are spread in a thin layer on the side of the screen next to the observer in the viewing apparatus.

[Ill.u.s.tration: FIG. 217.--EDISON'S SURGEON'S X-RAY APPARATUS.]

It is not to be understood that such viewing apparatus is necessary in taking a surgical photograph. In such case only the X-Ray tube, means for exciting it, the patient's body, and the sensitive photographic plate, are essential factors, the patient's limb or body being interposed between the light tube and photographic plate, so as to cause the X-Rays emanating from the tube to cast the shadow of the patient's bones, the bullet in his body, or other foreign object, directly upon the photographic plate, the sensitive and conscious plate obeying the will of these subtle rays, and receiving the impress of their actinic effect under conditions which it denies to ordinary light.

[Ill.u.s.tration: FIG. 218.--COMPLETE X-RAY APPARATUS IN USE.]

For exciting the vacuum tube any electrical machine capable of throwing a series of sparks across a gap of about five inches is sufficient.

Various electrical machines may be used for this purpose, the Holtz, or the Wimshurst gla.s.s plate machine, the Ruhmkorff, or induction coil, or even the high frequency transformer. A good example of a complete X-Ray apparatus is that in use at the Army Medical Museum at Was.h.i.+ngton, made by Otis Clapp & Son, and shown in Fig. 218. The electrical generator is of the Wimshurst type, and is shown in a large gla.s.s-enclosed cabinet on the right. The gla.s.s disks within are rotated either by a small electric motor shown on the floor, or by a hand crank above. The X-Ray tube, of globular or bulb shape, is shown just above the patient's hip, and its opposite poles are connected by wires to the opposite electrodes of the generator. When the current is switched on by the operator, the bulb is illuminated with the cathode rays, and the X-Rays, proceeding therefrom through the clothing and flesh of the patient, cast a shadow of the patient's hip joint upon the photographic plate placed on the cot beneath the patient.

[Ill.u.s.tration: FIG. 219.--X-RAY FOCUS TUBE.]

In the effort to secure greater sharpness in the image cast by the X-Rays, various forms of vacuum tubes have been devised. That shown in Fig. 219 represents one of the most important improvements. K is the cathode plate, formed of a concave disk of aluminum, which focuses the rays at a point near the center of the bulb. At this point a plate of platinum A, which metal allows practically none of the X-Rays to pa.s.s through it, is mounted on the anode in such an angular position that it gathers the focused rays and reflects them through the side of the tube.

They thus make a sharper shadow than when radiating from the more extended surface of the gla.s.s.

[Ill.u.s.tration: FIG. 220.--LOCATING A FOREIGN BODY IN THE BRAIN.]

In Fig. 220 is shown an X-Ray tube, as applied for locating a foreign body in the brain cavity, in which view the patient's head is interposed between the X-Ray tube and the fluorescing screen, or photographic plate, as the case may be; while Fig. 221 shows the application of the same devices to the body. In both these views the particular form of X-Ray apparatus is known as the "Fluorometer," made under the Dennis Patent, No. 581,540, April 27, 1897, and it is devised with reference to more accurately locating the foreign object by its shadow, for which purpose adjustable bracket-sights, seen in Fig. 221 on opposite sides of the body, are provided for bringing the X-Rays into proper alignment for projecting the shadow of the foreign body in true indicative position on the fluorescing screen, while a cross hatched grating behind the body, graduated in aliquot s.p.a.ces of an inch, furnishes a measured field, and forms an easy and quick means of platting the position of said object.

In the position of parts in the two figures the horizontal line, on which the foreign object lies, would be determined, but it would not indicate how deep in the object was, _i. e._, whether it was in the middle, or on one side. To determine this the fluorescing screen and grating are placed under the patient, and the X-Ray tube above, and the vertical line of the object is thus obtained. Both the vertical line and horizontal line having been obtained, it will be obvious that the foreign object will lie at the intersection of these two lines, which establishes for the surgeon its definite location.

[Ill.u.s.tration: FIG. 221.--X-RAY APPARATUS APPLIED TO THE BODY.]

It has been observed by Prof. Elihu Thomson, and also by Dr. Kolle, that the X-Rays are not absorbed and destroyed by the sensitive chemicals of a single photographic plate, but so potent and penetrating is their influence that the rays pa.s.s through and produce an image on a number of plates, placed one behind the other, thus affording means for multiplying the image at one exposure.

Among other uses of the X-Ray may be mentioned its capacity to detect spurious from genuine gems, the diamond giving a distinct color from its imitations, as do also most other precious stones.

A peculiar physiological effect of the X-Rays is their capacity to produce a severe effect on the skin, somewhat resembling sunburn. Such result, produced by long and continued exposure, has sometimes so deranged the skin tissues as to make sores that resulted in the entire loss of and renewal of the skin.

The discovery of the X-Ray by Prof. Roentgen may be fairly considered one of the most wonderful scientific achievements of the century, and his first memoir in 1895 is so full, clear and exact, as to have left very little more to be said about it. It is to-day, as it was found by him in 1895, the same mysterious, unseen, but positive force, a species of electrical energy without a domicile, and needing no conductor, a form of light pa.s.sing through closed doors, invisible itself, and yet lighting up certain substances with a halo of glory, and radically changing and decomposing others. Rivaling the sun in actinic power, and writing its autograph with an unseen hand, it is truly called the X-, or unknown, ray.

CHAPTER XXVI.

GAS LIGHTING.

EARLY USE OF NATURAL GAS--COAL GAS INTRODUCED BY MURDOCH--WINSOR ORGANIZES FIRST GAS COMPANY IN 1804--MELVILLE IN UNITED STATES LIGHTS BEAVER-TAIL LIGHTHOUSE WITH GAS IN 1817--LOWE'S PROCESS OF MAKING WATER GAS--ACETYLENE GAS--CARBURETTED AIR--PINTSCH GAS--GAS METER--OTTO GAS ENGINE--THE WELSBACH BURNER.

For many centuries the going down of the sun marked a cessation of man's labors, and among his first efforts toward increasing his efficiency was the prolongation of his hours of vision by artificial illumination.

Beginning with a sh.e.l.l for a lamp, a rush for a wick, and the fat of his game for oil, the first crude lamp was made, and while it shed but a feeble and flickering light, man ceased to go to sleep with the fowls and the beasts, and continued his labors and amus.e.m.e.nts into the night.

For many centuries the lamp held its exclusive sway, and probably will ever find a useful place; but with the discovery of coal gas and its practical manufacture the nights of the Nineteenth Century have been made to represent illuminated ill.u.s.trations of the world's progress.

Coal gas can hardly be claimed as an invention, however, for natural gas from the bowels of the earth had been observed and used in China from time immemorial. The holy fires of Baku on the sh.o.r.es of the Caspian and elsewhere were also thus supplied. The first steps toward its artificial production began in the latter part of the Seventeenth Century with Dr.

Clayton. Bishop Watson, in 1750, and Lord Dundonald, in 1786, also experimented with combustible gas made from coal, but the man who more than any other contributed to its practical manufacture and introduction was Mr. Murdoch, of Redruth, Cornwall, England. In 1792 Murdoch erected a gas distilling apparatus, and lighted his house and offices by gas distributed through service pipes. In 1798 he so lighted the steam engine works of Boulton & Watt, at Soho, near Birmingham; and in 1802 made public illumination of the works by this means on the occasion of a public celebration. In 1801 Le Bon, of Paris, used a gas made from wood for lighting his house. In 1803-4 Frederick Albert Winsor lighted the Lyceum Theatre, took out a British patent No. 2,764, of 1804, for lighting streets by gas, and established the National Light and Heat Company, which was the first gas company. In 1804-5 Murdoch lighted the cotton factory of Phillips & Lee at Manchester, the light being estimated as equal to 3,000 candles, and this was the largest undertaking up to that date. In 1807 Winsor lighted one side of Pall Mall, London, and this was the first street lighting. A disastrous explosion occurred shortly afterwards, and such eminent men as Sir Humphrey Davy, Wollaston, and Watt expressed the opinion that it could not be safely used; but the so-called "coal smoke" had come to stay, and in 1813 Westminster Bridge and the Houses of Parliament were lighted with gas. In 1815 there was general adoption of gas in the streets of London, and shortly afterwards in Paris. In 1805-6 David Melville, of Newport, R. I., invented a gas apparatus and lighted his house with it.

He took out United States patent March 18, 1813, and in 1817 contracted with the United States to supply for a year the Beaver Tail Lighthouse.

In 1815 James McMurtrie proposed the lighting of the streets of Philadelphia; Baltimore commenced the use of gas in 1816, Boston in 1822, and New York in 1825.

[Ill.u.s.tration: FIG. 222.--A COAL GAS PLANT.]

In Fig. 222 is shown a diagrammatic ill.u.s.tration of the princ.i.p.al features of a gas works, as employed throughout the greater part of the Nineteenth Century. On the left is seen the furnace, in which is arranged above the fire a series of retorts, which are in the nature of horizontal closed cast iron boxes. Only one of the series is visible in the view. Their ends project out beyond the furnace walls, and have doors for giving access to the interior, and each retort outside the furnace is connected by an upright pipe to an elevated cylinder called a _hydraulic main_. When the retort is charged with coal through its end door, and is heated red hot by the subjacent fire of the furnace, a heavy gas is driven off from the coal, which pa.s.ses up the pipe to the _hydraulic main_, where it partially condenses and leaves its heavier portions in the form of coal tar and ammoniacal liquor. The gas then pa.s.ses through the series of bent pipes, which form a _condenser_, where other remaining portions of the tar and other impurities are condensed, and drawn off from time to time in the little well shown on the left of the coil. From the condenser coils the gas pa.s.ses into the _purifier_, shown on the right of the coils as an enclosed case having a series of shelves on which is spread slaked lime, which takes up from the gas impurities in the form of sulphuretted hydrogen and carbonic acid. From this _purifier_ the gas pa.s.ses downwardly through a pipe into a large gas holder whose lower end is sealed in a water tank, and which gas holder is balanced by weights and chains pa.s.sing over pulleys. With the gas holder, the distributing mains of the city are made to connect to receive their supply. When the gas holder is full it is buoyed up by the lighter gas, and occupies an elevated position, and as its supply is used up, the gas holder settles down into the water.

In the operation of gas making many valuable secondary products are formed. The coal in the retorts is not entirely consumed, but is reduced to the condition of c.o.ke, and in this form is sold for fuel. The ammoniacal condensations are purified to form ammonia, while the coal tar, which but a few years ago was little more than a waste material, is now a valuable commercial product, being extensively used in the manufacture of the aniline, phenol, and naphthalene dyes, also in medicines and perfumes, and being used in crude form also as an important element in street paving compositions.

_Water Gas._--In 1875 an important era in gas making was inaugurated by the introduction of what is known as "_water gas_," so called for the reason that water in the form of steam is decomposed and its hydrogen, mixed with carbonic oxide gas, is mingled with a heavier carbon gas from oil, and is converted at a high temperature into a permanent, stable illuminating gas, at a much lower cost than coal gas.

[Ill.u.s.tration: FIG. 223.--LOWE'S WATER GAS APPARATUS, PATENTED SEPTEMBER 21, 1875.]

Fontana was the first to notice the decomposition of steam by incandescent carbon to form hydrogen and carbonic oxide. Ibbetson's British patent, No. 4,954, of 1824, represents the first application of this principle. This was followed by Alexander Selligue, who, in 1834, obtained a French patent, No. 9,800, and in 1842 produced water gas at Batignolles, a suburb of Paris. Sanders' United States patent, 21,027, July 27, 1858, was the basis of an experiment tried at the Girard House in Philadelphia. These, with Siemens' British patents, Nos. 2,861, of 1856, and 972, of 1863, for methods of constructing furnaces, const.i.tute the earlier steps in the development of water gas, although many other patents were granted prior to the latter date for various methods and forms of apparatus. The practical production and successful commercial use of water gas, however, began with T. S. C. Lowe, who obtained United States patent No. 167,847, September 21, 1875, and revolutionized the gas making industry. In less than a dozen years from the date of his patent 150 cities and towns in the United States were using water gas, and in 1886 the Franklin Inst.i.tute gave to Mr. Lowe a grand medal of honor for his invention, which of those exhibited that year was believed to contribute most to the welfare of mankind by cheapening the cost of light. Fig. 223 represents an ill.u.s.tration of the Lowe apparatus as shown in his patent, and whose operation is as follows: Valves 9 and 10 being open, an anthracite coal fire in generator chamber 1 gives off carbonic oxide gas, which pa.s.ses down pipe 2 and enters the base of superheater 3, where mixing with air coming down pipe 4, it burns to form an intense heat. The chamber, 3, is filled with loose pieces of fire brick, which are soon heated white hot. Valves 9 and 10 are then closed and steam is taken from an upright boiler, 6, and carried by a small pipe, 7, to the incandescent ma.s.s in chamber 3, and pa.s.sing down through it is superheated. This superheated steam pa.s.ses from the bottom of chamber 3 to the bottom of chamber 1, and then up through the ma.s.s of red hot coal. The intensely hot steam is thus decomposed into hydrogen and oxygen, and the oxygen unites with the carbon of the coal to form carbonic oxide gas. As hydrogen and carbonic oxide burn with only a feeble blue flame, these gases are now made richer in light giving carbon at this point by the addition of oil contained in an elevated tank, 8. This, dripping on the incandescent coal in chamber 1, is volatilized, and at the same time enriches and combines with the hydrogen and carbonic oxide to form a permanent illuminating gas (water gas) that pa.s.ses up pipe 5 and through the flues in boiler 6, to outlet 13, and thence on in the usual way to the condenser, scrubber and gas holder, which are not shown, and merely act to purify the gas. As the excessively hot water gas pa.s.ses through the boiler flues it furnishes the necessary heat to generate the steam. The air used in the process is forced at 12 into a drum in the smokestack, 11, and is heated by the escaping products of combustion. In practical operation there are two (or more) of the steam superheating chambers 3, working alternately, and one of them is being heated up while the other is superheating the steam.

Water gas has neither the illuminating nor the heating qualities of coal gas, and it is also much more poisonous. According to O. Wyss, one-tenth of 1 per cent. of uncarburetted water gas renders the air of a room injurious to health, and 1 per cent. is fatal to all warm-blooded animals. Notwithstanding these facts, however, its extreme cheapness and fairly satisfactory light have carried it into such general use that to-day it is said that two-thirds of all gas made in the United States is carburetted water gas.

_Acetylene Gas_ is a combination of two parts carbon and two parts hydrogen. It was discovered in 1836 by Edmond Davy, who produced carburet of pota.s.sium, and evolved acetylene gas therefrom by decomposing it with water. It was long known as _klumene_, and when burned it produced an intense white light. For a long time it was only produced in a small way in the laboratory. It is now made commercially by the mutual decomposition of water and calcium carbide, the latter giving off, when brought in contact with the water, acetylene gas, which rises in bubbles. In the reaction the carbon of the carbide unites with a portion of the hydrogen of the water, producing acetylene gas (C2H2), while the calcium of the carbide unites with the oxygen of the water and the remaining portion of the hydrogen and forms calcium hydrate, or slaked lime, which precipitates as a slush.

The union of carbon with an alkali metal, first accomplished by Davy in 1836, was followed in 1861 by the combination of carbon with calcium by Wohler. It was not, however, until the electrical furnace became an agency in chemical reaction that calcium carbide was made on a commercial scale. The production of acetylene gas for illuminating purposes began with the operations of Thomas L. Willson in 1893, and his patents, Nos. 541,137 and 541,138, of June 18, 1895, and 563,527 and 563,528 of July 7, 1896, cover the chemical process, the product, and the mode of operating. The reaction is a very simple one. A mixture of lime and carbon is subjected to the heat of an electric arc, and the carbon combines with the calcium of the lime to form calcium carbide, which appears on the market as dirty black stone-like lumps. The simplicity of the method of generating acetylene gas from this substance by merely bringing it in contact with water has greatly stimulated invention in this field. The art began practically in 1895, and since that time more than 500 patents have been granted for acetylene gas apparatus.

[Ill.u.s.tration: FIG. 224.--ACETYLENE GAS APPARATUS.]

A very simple apparatus for the purpose is shown in Fig. 224, in which a vessel containing water has an inverted bell or cylinder within it, open at its lower end. A basket or cage is suspended within the inner cylinder, and contains a few lumps of calcium carbide, which are first immersed in the water by being forced down by the rod supporting the same, which pa.s.ses through a stuffing box. Acetylene gas is immediately generated and its pressure forces the level of the water down in the inner cylinder, causing it to rise in the annular s.p.a.ce between said cylinder and the case. As the water level descends in the inner chamber it pa.s.ses out of contact with the calcium carbide, and the generation of gas is discontinued until some of the gas is drawn off or consumed at the burners, whose pipe is shown connecting with the gas s.p.a.ce of the inner cylinder. When so drawn off, the pressure in the inner cylinder is relieved, and the water therein rises to contact again with the calcium carbide and renews the generation of gas. This principle of automatic action is a very old one, and will be recognized by the student as that of the Dobereiner lamp of the chemical laboratory, invented by Prof.

Dobereiner, of Jena, in 1824.

[Ill.u.s.tration: FIG. 225.--MULTI-CHARGE ACETYLENE GAS GENERATOR.]

In acetylene gas apparatus a great variety of methods are employed for bringing the water and carbide into contact. Instead of the automatic pressure level principle described, many devices discharge a regulated quant.i.ty of powdered calcium carbide into the water, while in another form the water is discharged upon the calcium carbide. An example of the latter is given in Fig. 225, which represents the Criterion generator. A number of receptacles containing charges of calcium carbide are made to successively receive a regulated quant.i.ty of water, the gas being collected in a rising and falling holder.

Acetylene gas finds its princ.i.p.al uses for isolated plants, and in country houses. One form of using it is to compress it under high tension in cylinders, but this method has been attended with some disastrous explosions, and is discriminated against by the insurance companies.

Calcium carbide is now made in a large way by the Willson Aluminum Company, at Spray, N. C., and also at Niagara Falls and at Sault St.

Marie, Mich., and its cost is between 3 and 4 cents per pound.

Acetylene gas has an acrid, garlicy odor, and burns with an intensely white flame, and so superior is it to coal gas in illuminating power that it only requires a pipe of one-third the diameter of that used for coal gas to produce the same illuminating effect.

_Carburetted Air_ is another form of illuminating gas which has found some useful applications. This consists simply of air forced through some light hydrocarbon, such as naphtha, benzine or gasoline, and so saturated with the vapors of these volatile substances as to become an inflammable mixture. Many patents have been granted for apparatus operating on this principle, and it has been put to some practical use in country houses, and seaside resorts.