CHAPTER XII

MISCELLANEOUS RESEARCHES ON ROENTGEN RAYS.

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151. PUPIN AND SWINTON’S EXPERIMENT. SCIAGRAPHIC PLATES COMBINED WITH FLUORESCENT SALTS. _The Elect._, Lon., Apr. 24, ’96.—Prof. Pupin, of Columbia College (_Electricity_, N.Y., Feb. 12, ’96—the author saw him use it Feb. 7, ’96—), was among the first, and probably actually the first, to lessen the time of exposure by a fluorescent screen. Prof. Salvioni also worked in this direction at an early date. Prof. Swinton reported some details in the matter, and he was able to obtain a sciagraph of the bones of the hand in less than 10 seconds, with a moderately excited discharge tube, whereas, without the screen the time was two minutes. He experimented first with barium platino cyanide, but the results referred to were obtained with calcic tungstate, finely ground, and made up into paste by means of gum, and dried. He spread the same upon a celluloid sheet which was placed with the celluloid side against the photographic film. The difficulty experienced first was in the formation of spots on the negative, because some of the crystals fluoresced more than others. Such a defect, however, showed that the fluorescent salt increased the rapidity of the action upon the photographic film. The result of this experiment, as well as that of others, has sufficiently established the fact that the fluorescent screen is of great importance in connection with the art of rapid sciagraphy.

Phosphor sulphide of zinc is among those which hasten photographic action. (Chas. Henry, in _Comptes Rendus_, Feb. 10, ’96.) Dr. W. J. Morton employed the screen in taking the sciagraph of the thorax, p. 61. The advantageous use is also confirmed by BASILEWSKI (_Comptes Rendus_, March 23, ’96. From trans. by Louis M. Pignolet).—The photographic plate was covered with a sheet of paper coated with barium and platino cyanide, so that the two prepared surfaces were in contact, and the fluorescent paper was between the object and the plate.

J. W. Gifford, (_Nature_, May 21, ’96) tried a great variety of fluorescent bodies in combination with the photographic plate, and found that potassium platino cyanide was decidedly the best.

152. THOMPSON’S (S. P.) EXPERIMENT. PENETRATING POWER OF X-RAYS VARIES WITH THE VACUUM. _Comptes Rendus._ CXIII., p. 809. _The Elect._, Lon., April 24, ’96, p. 866. In a communication to the Académie des Sciences Prof. Sylvanus P. Thompson of the University College of Liverpool, argued that by one kind of X-rays the bones of the hand were more easily penetrated than by another kind. The two varieties were produced by different vacua. § 75 and 76. Let the vacuum be supposed to become higher and higher. At the first generation of the X-rays, the fluorescent screen showed that the bones of the hand cast very dark shadows. With increase of the vacuum, the shadows of the bones were very faint. This result is also obtained by reduction of temperature. § 152_a_.

152_a_. BLEEKRODE’S EXPERIMENT. PERMEABILITY AT LOW TEMPERATURES INCREASED. _Elect. Rev._, Lon., June 12, ’96.—Experiments performed by him confirmed those of Edison. § 135. An experiment by Prof. Dewar strongly confirmed the results. They noticed the same peculiarity that Edison did, namely, that the shadow of the finger exhibited the flesh and bones as if they were equally transparent. Varied tests showed that the reduction of the temperature of glass increased its permeability.

153. MURRAY’S EXPERIMENT. REDUCTION OF THE CONTACT POTENTIAL OF METALS BY X-RAYS. _Trans. R. So._, Mar. 19, ’96. _The Elect._, Lon., Apr. 24, ’96, p. 857. J. R. E. Murray of the Cavendish Laboratory, at the suggestion of Prof. J. J. Thomson, carried on a long series of careful experiments, to find whether the contact potential of a pair of plates of different metals was, in any way, affected by the passage of X-rays between the plates. All the ordinary precautions were taken. The contact potential was measured by Thomson’s (Kelvin) method, see _Trans. Brit. Asso._, 1880. The important result obtained, was that “the air through which the rays pass, § 90, is temporarily converted into an electrolyte, § 47, and when in this condition forms a connection between the plates, which has the same properties as a drop of acidulated water, namely, it rapidly reduces the potential between the opposing surfaces of the plates to zero, and may even reverse it to a small extent.”

154. NODON’S EXPERIMENT. TRANSPARENCY OF DIFFERENTLY COLORED MEDIA TO THE X-RAYS. _Comptes Rendus_, Feb. 3, ’96. From trans. by Louis M. Pignolet. The rays were passed through two openings in a thick metal diaphragm, one of which was covered by an uncolored piece of gelatine and the other by a piece tinted with the color to be tested. The two images were received on the same plate. The various colors tested were traversed with equal facility by the rays, § 68 and 82.

The investigation described above was made by Albert Nodon at the Laboratoire des Recherches Physiques à la Sorbonne.

This agrees with Bleunard who found that colors seemed to have no influence on the passage of the rays as water colored with various aniline colors offered no more resistance than when pure. From trans. by L. M. P. _Comptes Rendus_, March, ’96.

A. and L. Lumière (_Comptes Rendus_, Feb. 17, ’96,) observed that the X-rays act in the same manner upon colored photographic plates rendered sensitive to various regions of the spectrum. Thus, plates sensitive to red, yellow and green gave exactly the same impression, provided they had the same general sensibility to white light. While this may not be accurately so, it illustrates that materials are penetrated by X-rays independently of the laws of color.

155. MESLANS. CHLORINE, IODINE, SULPHUR, PHOSPHORUS, COMBINED WITH CERTAIN COMPOUNDS, INCREASE OPACITY TO THE X-RAYS (_Comptes Rendus_, Feb. 10, ’96. From trans. by Louis M. Pignolet.)—Carbon in its various forms was found to be very transparent, also organic substances containing, besides carbon, only the gaseous elements hydrogen, oxygen and nitrogen; but this transparency was far from uniform. Organic substances,—ethers, acids, nitrogenized compounds (_corps azotes_),—were easily traversed by the rays; but the introduction of an inorganic element, as particularly, chlorine, sulphur, phosphorus, and, above all, iodine, renders them opaque. § 82. This occurs also with sulphates of the alkaloids. Iodoform, the alkaloids, picric acid, fuchsine and urea are very transparent. Metallic salts are very opaque, but this varies with the metal and the acid. Bleunard went further into details. The opacity of solutions of salts increased with the atomic weight of the metal and of the metalloid. Water was easily traversed by the rays. Solutions of bromide of potassium, chloride of antimony, bichromate of potash offered considerable opposition to the passage of the rays. Solutions of borate of soda, permanganate of potassium were easily traversed. The liquids were held in paper boxes. The experiments above related were conducted by Maurice Meslans at l’École de Pharmacie de Nancy.

156. BUQUET & GASCARD’S EXPERIMENTS. ACTION OF THE X-RAYS UPON THE DIAMOND AND ITS IMITATIONS; ALSO UPON JET. _Comptes Rendus_, Feb. 24, 96. From trans. by Louis M. Pignolet.—Sciagraphs taken by the X-rays showed that diamonds became transparent, and their shadows disappeared with long exposures; but imitation diamonds remained opaque under the same conditions. Jet was distinguished from its imitations by the same method. The diamond and jet cast clearer shadows on a fluorescent screen than their imitations.

The above tests were made by Albert Buquet and Albert Gascard, at the Cabinet de Physique de l’École des Sciences de Rouen.

The half-tone on lower half of adjacent page, 164, was taken from a sciagraph by Prof. Dayton C. Miller, of Case School of Applied Science. The differences of opacity are proved, because all were of same thickness and exposed simultaneously.

Prof. Sylvanus P. Thompson (_The Elect._, Lon., May 18, ’96) confirmed the above, and also found that, although the diamond is more transparent than glass, it is more opaque than block carbon or graphite.

Mineralogists are thus enabled to submit minerals to the X-ray test in making analyses.

157. DUFOUR’S EXPERIMENT. INACTIVE DISCHARGE TUBES MADE LUMINOUS BY X-RAYS. _Comptes Rendus_, Feb. 24, ’96. From trans. by Mr. Pignolet.—He observed that very small and sensitive Geissler tubes phosphoresced when exposed to X-rays. § § 22, 23.

158. BEAULARD’S EXPERIMENTS. NON-REFRACTION OF X-RAYS IN A VACUUM. _Comptes Rendus_, Mar. 30, ’96. From trans. by Louis M. Pignolet. With prisms of ebonite, F. Beaulard held that no decided deviation could be observed within the vacuum.

159. CARPENTIER’S EXPERIMENT. SCIAGRAPH SHOWING THE PARTS IN RELIEF ON A COIN. _Comptes Rendus_, Mar. 2, ’96. From trans. by Louis M. Pignolet. An imprint of a coin stamped upon a thin piece of well annealed aluminum by pressing the coin against the aluminum, was reproduced in a sciagraph. The raised parts of the coin were scarcely 8/100 of a millimeter high. The aluminum was 5/10 millimeter thick. This result is admirably represented by the sciagraph of an aluminum medal on page 166, taken by Prof. Dayton C. Miller, of Case School of Applied Science, _Elect. World_, N.Y., Mar. 21, ’96, who also made a sciagraph of a copper plate 1/4 inch thick having blow holes which appeared in the picture, but they could not be detected by light, serving to illustrate an application of the new discovery in testing the homogeneity of metals.

160. WUILLOMENET’S EXPERIMENTS. TRANSPARENCY OF THE EYE TO THE X-RAYS DETERMINED BY SCIAGRAPH OF BULLET THEREIN. _Comptes Rendus_, Mar. 23, ’96. A sciagraph taken with an exposure of _three hours_ showed perfectly a lead shot introduced into the vitreous media of the eye of a full grown rabbit. Therefore the opacity of the media of the eye was not absolute.

In a second series of experiments by Dr. Wuillomenet a human head was used, but the results were negative in spite of a great intensity of the rays and a long exposure, § 82.

161. FERNAND RANWEZ’S EXPERIMENTS. APPLICATION OF THE X-RAYS TO ANALYSIS OF VEGETABLE MATTER. _Comptes Rendus_, Apr. 13, ’96. From trans. by Louis M. Pignolet. Sciagraphy can render valuable services in analytical researches and specially in the analysis of vegetable foods where they will show the most usual adulterations consisting of mineral substances.

This method offers several advantages for small samples of the substances can be examined. The samples are not chemically changed. A great number of tests can be made in a short time. Lastly, the sciagraph obtained affords a permanent record.

The tests were made on samples of adulterated saffron composed of mixtures of pure saffron and saffron coated with sulphate of barium. A sciagraph taken with an exposure of three minutes showed scarcely visible imprints of the pure but strong impressions of the adulterated. See sciagraph of pen, (mineral) in holder, (vegetable), in cut at upper part of p. 164, which also shows the graphite in a wooden pencil.

162. ERRERA’S EXPERIMENT. ACTION OF THE X-RAYS ON PHYCOMYCES. HERTZ WAVES AND ROENTGEN RAYS NOT IDENTICAL. _Comptes Rendus_, March 30, ’96. From trans. by Louis M. Pignolet.—_Phycomyces Nitens_, when submitted to the asymmetrical action of Hertz electric waves, became curved, according to Hegler. Errera found a Phycomyces was not affected by the X-rays, thus denoting an absence of Hertz waves in the rays. Credit for the above result is due to L. Errera, from experiments made at the Laboratoire Physique and the l’Institut Solvay (Université de Bruxelles).

163. GOSSART, CHEVALLIER, FOUTANA AND URUANNI’S EXPERIMENT, IN CONJUNCTION WITH J. R. RYDBERG. NO MECHANICAL ACTION OF X-RAYS. _Comptes Rendus_, Feb. 10, Mar. 23, Apr. 13, ’96. From trans. by Louis M. Pignolet.—The former party alleged that radiations from a discharge tube caused a cessation of the rotation of the vane of the radiometer. J. A. Rydberg was not inclined to confirm such action. A. Foutana and A. Uruanni made experiments and concluded that the action was due to an electro-static force, having noticed that a Leyden jar would also produce such effect. The author made some experiments to determine the matter in reference to X-rays at a distance outside of the electro-static field. The rays would neither stop the vanes nor cause them to rotate. He made some other experiments to detect whether there was any direct mechanical power possessed by the rays; but if any, it was exceedingly feeble.

T. C. Porter made some experiments at Eton College, (_Nature_, June 18, ’96,) which confirmed the above results, finding that the radiometer is entirely inert to the Roentgen rays, whether they be from a properly electrically screened hot or cold tube. He distinguished between the caloric conditions, for he found that, not only will reduction of temperature vary the penetrating power of the rays, § 135 and 152_a_, but also will an increase of temperature.

164. BATTELLI’S EXPERIMENT. X-RAYS WITHIN DISCHARGE TUBE. _Nuovo Cimento_, Apr., ’96, p. 193; _Elect. Rev._, Lon., June 12, ’96.—Shortly after the announcement of the discoveries of Lenard and Roentgen, it would have been considered strange to assert that X-rays may exist inside of the discharge tube. Battelli certainly correctly infers, that inasmuch as X-rays apparently originate from the point where a material object is struck by the cathode rays, § 115, it would follow that when the said object is within the vacuum space, X-rays are propagated before they reach the glass wall of the discharge tube. It has already been noted (DeMetz, § 63_a_) that photographic action may be produced within the discharge tube. Battelli has confirmed this, not by a crude experiment, like that (failure) of some authority in England, but by a series of severe tests, leaving no doubt as to the production of photographic action. He discovered in connection with several subordinate phenomena that among the rays capable of producing a photographic impression within the discharge tube, some were deflected by a magnet and others were not, from which he concluded that X-rays may exist inside the tube, in conjunction with cathode rays, before collision with the anti-cathode. The experiment consisted in deflecting the rays by a magnet, the film being in the path that the rays would have had without a magnet. There was also a film in the path of the deflected rays. Photographic action was produced upon both. He varied the vacuum. Photographic action began at 3-10 mm., had its maximum at 1-70 mm., after which it remained constant. No photographic action was obtained upon a film placed within the tube opposite the anode, except in one case where it was exceedingly weak. Lenard continually inferred that there must be two kinds of cathode rays. § 75. Battelli has certainly sifted the two rays apart and thus proved Lenard’s conjectures. § 61_b_, p. 47. _The Elect. Rev._, Lon., pays tribute to Battelli, by offering the following opinion: “We have no hesitation in saying that Battelli, by means of interesting and ingenious experiments, has made the greatest advances in the theory of the X-rays since their discovery by Roentgen.”

In many cases the author has omitted stating, in taking sciagraphs, that the films were protected from ordinary light by opaque material. This, as a matter of course, has always been understood. Battelli also had the films wrapped in material opaque to ordinary light. Experimenters should, if possible, always employ aluminum for this purpose, because the author has always noticed that black paper or cloth permits a great deal of light to come through, even when in double thickness.

Prof. Sylvanus P. Thompson (_The Electr._, Lon., June 26, ’96) located a wire in a focus tube in the path of the rays between the platinum reflector and the wall of the tube. Not only was there a sciagraph of this wire produced in the sciascope, but also the Crookesian shadow of the wire on the wall of the bulb. For this experiment the exhaustion must be quite high. “At no state of exhaustion did the platinum reflector convert all the internal cathode rays into X-rays.” Both shadows were cast by the platinum reflector as the origin. More or less of the rays between the reflector and the glass were sensitive to a magnet.

165. BLEYER’S EXPERIMENT. COMBINED CAMERA AND SCIASCOPE. _Elect. Eng._, July 1, ’96; _Royal Acad. Med. & Sur._, of Naples, Italy.—As early as April 7, J. Mount Bleyer, M.D., of Naples, constructed and used the apparatus shown in the adjacent cut, p. 169. The picture is self-explanatory. Attached to an ordinary camera is a flaring sciascope, for receiving the temporary sciagraph of the hand, for example. The X-rays are converted into luminous rays by the fluorescent screen, and, therefore, the camera will serve to take a picture by means of the luminous rays from the sciagraph of the hand. The cut represents also an induction coil and a discharge tube. Soon afterwards, it was reported by an English paper that Dr. Levy, of Berlin, and others of England, had also made similar tests with success. In order to illustrate the applicability of the combination, Dr. Bleyer took many sciagraphs with the camera. He calls it the photofluoroscope, which, however, will probably not meet with favor for the name does not suggest the nature of the instrument. When two radically different devices are combined into one, it is difficult to formulate an acceptable single word, and, therefore, the instrument will probably always be called by some of the following terms: A camera with sciascopic adjustment, or combined sciascope and camera, or corresponding combinations with the word fluoroscope.

From the time that Roentgen’s discovery was announced, scientists throughout the world have made careful experiments, up to date, in all possible directions, and the time has now come when the number of experiments is rapidly decreasing, only one or two being noted now and then in the scientific press, and consisting mostly in repetition, with occasionally a slight departure, involving a radically new subordinate discovery; but in view of the great number of scientists, and of their high standing as careful experimenters, and because also of their desire to be correct in their inferences, there might seem to be little else to be investigated. Time only will tell. Before passing to the final chapters relating to other matters, a few more experiments are related in the briefest manner.

166. Prof. Sylvanus P. Thompson confirmed non-polarization, (_Phil. So._, June 12, ’96, and _The Electr._, Lon., June 26, ’96.)

Dr. John Macintyre (_Nature_, June 24, ’96) carried on a long series of experiments with tourmaline, and also arrived at the conclusion that polarization of X-rays is practically impossible, § 97, at end.

167. In the same paper Prof. Thompson showed conclusively that there is a diffuse reflection of X-rays. § 81 and 103. A curious experiment consisted in his obtaining dust figures, § 36. by the discharge of an electrified body by X-rays. In another experiment he caused reflection of the rays from the surface of sodium located in a vacuum. The amount reflected was a minimum for normal incidence and increased at oblique incidence.

168. Prof. Oliver J. Lodge, F.R.S., reported in _The Electr._, Lon., June 5, ’96, further detail experiments in the line set out in § 113. He proved conclusively, as stated by the editorial in _The Electrician_, that a positive charge has increasing effect upon the ray-emitting power of the surface exposed to the cathodic radiation.

169. At Eton College, T. C. Porter (_Nature_, June 18, ’96) confirmed the experiments of others by showing that the blackened face of the thermopile connected with a very sensitive galvanometer was not influenced in any manner by X-rays.

170. Prof. William F. Magie, of Princeton, N. J., made a careful experiment in relation to diffraction. _Princeton College Bulletin_, May, ’96. The experiment would certainly prove that if X-rays are due to vibrations, the latter are of a different order from those occurring in light rays, for the slits exhibited light diffraction very well, but there was no evidence, by a widening of the image on the plate, that X-rays had been diffracted in the slightest degree. § 110 and 110_a_.

171. Prof. Haga, of Groningen University, at the suggestion of Mr. J. W. Giltay, (_Nature_, June 4, ’96,) made some very crucial tests, with numerous precautions, in reference to the action of X-rays upon selenium, and the results were so positive that they thought that a practical application could be made by using selenium for detecting X-rays, both qualitatively and quantitatively. In repeating the experiments, it must be borne in mind that one half hour or so is required for selenium to return to its former degree of ohmic resistance after being struck by light or heat or X-rays.

_Total number of_ § § _to this place, 199._