Roentgen Rays and Phenomena of the Anode and Cathode.

by Edward P. Thompson

Fig. 2.—Hammer’s Historical Collection of Incandescent Lamps, contained in case having the dust figures. [§ 36], p. [21].

36b. Independently of the above peculiar phenomenon, Mr. Hammer recently had on exhibition at the Electrical Exposition of the National Electric Light Association in New York, 1896, a portrait formed of fine dust upon a pane of glass. The circumstances were as follows, as remembered by the author. Mr. Hammer happened to be in some place where an artisan was removing a photograph from an old frame. The glass which protected the portrait exhibited a fac-simile in dust on the inner surface. The glass had not been in contact with the photograph, because of a thick passe-partout surrounding the picture. Neither was the glass an old negative photographic plate. Further test and inspection tended to prove that the dust picture was executed by some action of the heat or light of the sun. Prof. Benjamin F. Thomas, of the University of the State of Ohio, in an interview, scarcely thought that the result was due to convection, because the dust print was so sharply defined. The principle of the discharge of bodies by light may be applicable perhaps, but further experiment would be necessary as a more secure foundation. It is common to find the print of a picture in a book upon the opposite page, being due merely to the pressure of the inked surface, as in the art of printing. This explanation cannot be applied to the dust portrait, because there was no contact between the photograph and the glass.

37. Karsten’s Experiment. Electrical Images Developed by Condensed Moisture. Riess’s Reibungselect., vol. II., § 739.—He arranged the following articles in the following order: First, a metal plate suitably insulated; secondly, a piece of a glass plate on top of the metal plate, and, thirdly, a coin or small metal object on top of the glass. Sparks were then allowed to pass for several minutes from a Holtz or similar machine to the coin. The image of the latter appeared by removing the glass plate and breathing upon it. The bas-relief of the image on the coin also was visible in all its details, appearing as in Sanford’s Electrograph, [§ 35]. Theoretical considerations led others to believe that the figures of Riess and Karsten are due to a different cause from that involved in the figures of Lichtenberg, for the former are thought to be due to a molecular action of a permanent nature upon an insulating material. A slight change in the color often occurs, thereby outlining the object.

Dust-portrait on Glass, [§ 36]., p. [23], discovered by William J. Hammer.
Lighter portions, dust; darker portions, due to less or no dust. Finger-marks across the shoulder and at right. Exposure 8 years. Portrait as sharp and clear as a daguerreotype. During exposure in frame, distance of glass from photograph, 1/16 inch. Above half tone was made from a photograph of the dust-portrait only after several unsuccessful attempts by different photographers. The original dust-portrait is scarcely visible. Let every one examine closely glass plates when taken from old frames.

37a. McKay’s Experiment. Magnetographs. From Personal Notes by Request. April, 1896.—Although this experiment does not belong to that class connected with discharge tubes, yet the phenomenon has a theoretical interest in connection with X-rays. He obtained a photograph of different objects in the dark by means of radiations from the poles of an electro-magnet after two hours’ exposure, but it need not have been so long, as he obtained clear images in five minutes in one experiment with frequent variations of current by means of a rheostat, and by approach and recession of the armature. The elements involved in the experiment were arranged in the following order: First, a large inverted magnet for supporting 100 lbs., the poles hanging downward. Next in order was a wooden board pressing flatwise against the ends of the poles of the magnet. Next, the objects and the sensitive plates backed thereby and all enclosed in a completely opaque wrapping extending over the sides, face, back, etc., of these two elements. Next in order was an armature about as heavy as the magnet would support. The cut herein represents the photograph that was produced of the different objects named. By reading Prof. McKay’s very detailed description in the Scientific American, April 18, 1896, p. 249, the reader may feel certain that the photograph was not due to light for he tried the experiments in different ways and with various precautions. In a course of experiments carried on by student Austin, about Feb. 15, ’96, in the Dartmouth laboratory, a sciagraph of what appeared to be the lines of force was obtained by means of X-rays, but upon repeating the experiment the result was negative. See Elect. Engineer, Mar. 11, ’96, p. 257. Article by E. B. Frost.

XI

38. Piltchikoff’s Experiment. Liquid Bas-relief Facsimiles by Electric Discharge. Pro. Acad. Sci., Paris, March, ’94. The Electr., Lon., April 13, ’94, p. 656.—These shadow pictures were obtainable either with the anode or cathode, the particular machine employed being a large Voss. To either pole was electrically connected a pointed wire which was held just above the surface of castor oil, in a copper pan. A remarkable effect was obtained of the shadow of a piece of mica, Fig. [XI], of whatever shape, located between the point and the surface. [§ 24]. Let it be observed that this shadow was not one in the sense of light and darkness but it consisted of a plateau within a depression, the former being of the same shape as though it were a shadow of the mica triangle. To illustrate the experiment better, let the mica be supposed to be removed, then will there be a depression formed in the oil upon bringing the metallic point near to the surface. Now insert the insulating sheet between the point and the surface, then will there be an elevation within the depression of the same shape that the shadow would be.

39. Gernez’s Experiment. Distillation of Liquids by Discharge. Phys. So., Paris, 1879. Nature, Nov. 20, 1879, p. 72.—In order that the apparatus with which he experimented may be understood, imagine a tube standing vertically in another tube. The two concentric tubes communicate with each other at the top only. The Holtz machine is the generator. The liquids in the two tubes at the beginning stand at the same level. Sparks are passed through the adjacent air, which is in contact with both liquids. The liquid at the cathode rises and at the anode falls. [§ 38]. Such was the experiment performed by Gernez. He was inclined to conclude that the effect was due to “An electrical transport of liquids along the moistened surfaces of the tubes.” When the liquid was alcohol, it actually went over as by distillation, three times as fast as water. A soluble salt in water increased the rate of distillation; and so also did the addition of a small quantity of sulphuric acid or ammonia. No distillation of bi-sulphide of carbon, tetra chloride of carbon, nor turpentine occurred. Query: Can alcohol be concentrated or practically distilled upon this principle?