RAY 



448 



REACTION 



ing a negative charge. R.s, Cathode, or Kathode, the 

 stream of negatively electrified particles first observed by 

 Pliicker emanating from the cathode of a Crookes tube 

 and passing in straight lines regardless of the anode. 

 They are capable of deflection with a magnet and pro- 

 duce fluorescence and heat wherever they impinge. 

 R.s, Diacathodic, bluish rays obtained by directing 

 the ordinary cathode rays upon a piece of wire gauze 

 or upon a spiral of wire which is itself negatively elec- 

 trified. They are not directly affected by a magnet, 

 they can produce fluorescence of the glass where they 

 meet the walls of the tube and can cast shadows of in- 

 tervening objects ; but the fluorescence is of a different 

 kind, for ordinary soda glass gives a dark orange 

 fluorescence instead of its usual golden-green tint. (S. 

 P. Thompson. ) R.s, Gamma, a type of Becquerel 

 rays more highly penetrating than the a-rays and fi-rays, 

 but insignificant in energy compared with them. R.s, 

 Goldstein, cathode rays which have been altered by 

 being passed through a perforated metallic plate. Syn., 

 Positive rays ; Ger. Kanalstrahlen. R.s, Goodspeed 

 (Arthur W. ), reported rays which emanate from the 

 human body and are strong enough to make a photo- 

 graph ; probably identical with the n-rays of Blondlot. 

 R.s, Hard, Rontgen rays coming from a tube the ex- 

 haustion of which is sufficient to cause a considerable 

 difference in the potential between the cathode and the 

 anode and in the velocity of the cathode rays. They 

 have high penetrating powers. Cf. R.s, Soft. R.s, 

 Hertzian, radiant energy having the greatest wave 

 length of any yet discovered in the spectrum, supposed 

 to be several miles in length. These rays have the 

 peculiar property of converting poor electric contacts 

 into good ones when they fall upon them. R.s, 

 Heterocentric. See Heterocentric. R.s, Homo- 

 centric. See under Homocentric (Illus. Diet.). R.s, 

 Lenard, cathode rays outside the vacuum tube as de- 

 scribed by Philipp Lenard (1894) and secured by him 

 by means of an aluminium window. R.s, Light, 

 rectilinear transverse vibrations of ether, propagated at 

 the speed of 186,400 miles per second. They may be 

 refracted, reflected, and polarized. See Light (lllus. 

 Diet.). R.s, N, a form of ether waves discovered by 

 Blondlot (1903) and named after the initial letter of 

 Nancy, in the university of which his researches were 

 conducted. They increase the brightness of an electric 

 spark or the luminosity of phosphorescent bodies ; they 

 are emitted by the jr-ray tube, by an Auer-Welsbach 

 incandescent gas mantle, by the ordinary gas flame, 

 but not by a Bunsen burner ; the sun emits these in 

 abundance, as does the Nernst lamp. Compression,' 

 torsion, and strain of many solids will cause the emis- 

 sion of the rays; living bodies, plants, and animals 

 emit them. Cf. R.s, GoodspeecV s. R.s, Niewen- 

 glowski's, certain luminous rays emitted from phos- 

 phorescent substances which may pass through opaque 

 screens and affect sensitive plates. Niewenglowski 

 was probably the first to establish the existence of such 

 rays. R.s, Paracathodic, rays closely resembling 

 cathode rays, produced when ordinary cathode rays 

 strike upon an anticathodr, as in the focus tubes. If 

 the vacuum is low, they are emitted from the anticathode 

 in nearly equal intensity in all directions. They can 

 be deflected electrostatically and magnetically and can 

 cast shadows of all objects on the glass walls. (S. P. 

 Thompson.) R.s, Photographic. See R.s, Ultra- 

 violet.. R.s, Polar, the astral rays of the mitotic figure. 

 R.s, Positive. See R.s, Goldstein's. R.s, Rontgen, 

 that form of radiant energy discovered by the German 

 physician Wilhelm Konrad Rontgen, 1895, and called 

 by him .r-ray. R.s, S. of Sagnac, secondary rays 

 emanating from metals on which Rontgen rays fall and 



distinguished from the primary rays irregularly refracted 

 by difference in character, not being nearly so penetrat 

 ing; the lighter the metal struck by the primary rays, 

 the more penetrating the secondary rays. R.s, Soft, 

 rays coming from a tube the pressure in which is fairly 

 low; they are readily absorbed. Cf. R.s, Hard. R., 

 Spiracular, the small cartilage which supports the 

 operculum of the blowhole, between the eye and the 

 ear of the shark. R.s, Ultraviolet, waves of the 

 luminiferous ether which do not affect the retina. 

 They can be reflected, refracted, and polarized; they 

 will not traverse many bodies that are pervious to the 

 rays of the visible spectrum ; they produce photographic 

 and photochemic effects ; they rapidly destroy the 

 vitality of bacteria ; they will discharge an electroscope 

 if electrified negatively, but not if electrified positively; 

 they excite bright green luminescence in willemite and 

 blue luminescence in polysulfid of calcium. Syn., 

 Actinic rays; Photographic rays. R.s, Uranium. 

 See R.s, Becquerel. R.s, X-, rectilinear longitudinal 

 vibrations of the ether detected by Rontgen (1895). 

 They are incapable of being refracted, are not deflected 

 by magnetic or electric forces, but may be reflected to 

 a slight extent, though the greater part of the effect 

 produced by the incidence of the primary rays of high 

 penetrating power is the emission of secondary rays of 

 small penetrating power. They affect a photographic 

 plate and the retina ; they penetrate and traverse many 

 bodies that are opaque to luminous rays ; they readily 

 traverse living tissues and influence the nutrition of the 

 deeper ones ; they have no appreciable effect on the 

 vitality of bacteria ; they will discharge an electroscope 

 either positively or negatively electrified ; they will 

 excite bright green luminescence in willemite and 

 white luminescence in calcium polysulfid ; rock salt is 

 opaque to x-rays. 

 Reaction. (Seelllus. Diet.) R., Addition, the direct 

 union of two or more molecules to form a new mole- 

 cule. R., Bareggi's, twenty or thirty drops of blood 

 collected in a small test-tube and allowed to stand for 

 24 hours will show a nonretracted clot and a small 

 amount of serum if the blood has been taken from a 

 typhoid patient. In tuberculosis, on the other hand, 

 the clot will retract considerably and an abundance of 

 serum will be formed. R., Bechterew's, the minimum 

 strength of the electric current necessary to provoke 

 muscular contraction requires a gradual diminution at 

 every interruption of the current or change in density, 

 to prevent tetanic contraction which will occur if the 

 initial strength is maintained. It is observed in tetany. 

 R., Bremer's. See under Tests. R., Chameleon, 

 the peculiar change of color observed in cultures cd 

 Pseudomonas fyocyanea, from green to brown and back 

 to original brown. R., Clump, the agglutination oi 

 bacteria or of leukocytes as the result of the action ol 

 certain enzymes, lysins, or toxins. R.. Consensual, 

 reaction which is independent of the will. R., 

 Ehrlich's Diazo. See under Diato (Illus. Diet.). 

 R., Electric, response to electric stimulus. R., 

 Franklinic, of Degeneration, a rare form of reaction 

 of degeneration produced by static electricity and similar 

 to that obtained by the faradic current. R., Ger- 

 hardt's Bordeaux. See under Tests. R., Gruber's, 

 the addition of some of the cultures of Spirillum 

 choleric asiatica to the serum of an animal rendered 

 immune to cholera causes these organisms to become 

 nonmotile and to agglutinate. The reaction does not 

 occur with other species. R., Gruber-Widal's. See 

 R. , WidaVs. R., Iodin, iodophilia. See lodin- 

 reaction. R., Jolly's Electric, when the contractility 

 of a muscle is exhausted by the faradic current, it can 

 still be excited by the influence of the will, and, in- 



