152a. 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.
From Sciagraph of Pencil, Key, Fountain-pen, and Coin. [§ 161].
By Prof. McKay, Packer Institute.
