2l8 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Sept., 1905. 



The N-Ratys^f Blondlot 



By J. J. Stew.\rt,M.A.,B.Sc. {Priiici/'al 0/ the Tfchniiiil 



Institute, Nrwfort). 

 In the early summer of the year 1903 M. Blondlot, of 

 Nancy, published in the Comptes Rendtis of the French 

 Academy of Sciences an account of some remarkable 

 experiments he had carried out on certain rays which 

 were emitted by a gas burner. He found that an 

 ordinary .Auer burner sent out rays resembling those 

 of light and capable of penetrating metals, black paper, 

 wood, cardboard, &c. The rays, after passing through 

 these obstacles in their path, were able to produce 

 effects in the region beyond. These effects manifested 

 themselves especially by their behaviour towards a 

 small electric spark which they caused to become 

 noticeably brighter. A record of this action was ob- 

 tained by M. Blondlot, who arranged a pair of sensitive 

 photographic films so that one was acted upon by the 

 ordinarv electric spark from a small induction coil, the 

 other by the spark from the same coil under similar 

 conditions except that in the second case the spark 

 was excited by the presence of the rays and had thus 

 become brighter. The enhanced brilliance of the spark 

 is indicated by the different effects on the sensitive film, 

 and pictures of the two films, one exposed to the action 

 of a succession of sparks under the influence of the rays 

 from the Auer burner for 40 seconds, and the other 

 with the rays from the .Auer burner cut off by the inter- 

 position of moistened paper, are given in an early paper 

 by ^f. Blondlot. The absorption of these new rays by 

 water, especially water containing salt in solution, or 

 by moist paper is one of their remarkable and unex- 

 plained characteristics. 



The emission of these rays was noticed by M. Blond- 

 lot when using a Crookes tube for the production of 

 Rontgen rays. He was led to suppose that they were 

 to be very generally met with and were given out by 

 various sources of light and heat, such as an Auer 

 burner or a piece of hc.ited metal. \s these researches 

 were carried out at the University of Nancy, where 

 M. Blondlot is one of the professors, he gave to the 

 radiations the name of X-ravs from the first letter of 

 the name of the town. Experiments on the behaviour 

 of the N-rays seemed to indicate that they were capable 

 of refraction and polarisation like the rays of ordinary 

 light, and a beam of the rays appeared to be made up 

 of different rays of very various refrangibility. 



.Another strange property of the new rays was that of 

 increasing phosphore.scence. Thus, if the N-rays con- 

 centrated by a quart/! lens were caused to strike upon 

 a screen of sulphide of calcium already phosphorescing, 

 the phosphorescence was increased. This has been 

 used as a means of detecting the presence of the rays, 

 but the effect of heat on phosphorescence is very similar. 



Further investigation of the N-rays seemed to 

 indicate that they were given out by all bodies in a 

 state of strain — by a bent piece of steel, a stretched or 

 bent rod, or a file in which, during the process of 

 manufacture, the malf-rial was subjected to stress re- 

 sulting «n a state of permanent strain. Extraordinary 

 accounts were given of the emission of N-rays from 

 pieces of metal, such as old weapons found in ex- 

 cavated cities or amongst the remains of buildings 

 dating from Roman times in the south of France. 



Bending or stretching wood or metal was found to 

 cause the emission of N-rays, which generally mani- 

 fested themselves by causing increased phosphore.scence 

 in sensitive substances.. Sonorous vibrations were 



next observed as exciters of N-rays. M. Mace de 

 Lepinay gave an account of experiments which showed 

 increased luminescence of sulphide of calcium in the 

 presence of sonorous bodies, such as cylinders of 

 bronze when set in vibration. Even the alternate com- 

 pressions and rarefactions of the air when transmitting 

 the vibrations of sound seemed sufficient to originate 

 N-rays and increase the brightness of a phosphorescing 

 screen. 



Further investigations by Blondlot led him to de- 

 scribe the dispersion of N-rays when refracted through 

 prisms made of aluminium. As source of the N-rays 

 in these experiments a Nernst lamp was used shut up 

 in a cvlinder of sheet iron in which a slit for the exit 

 of the rays was arranged, which was closed bv a sheet 

 of aluminium permeable to the rays. The issuing 

 N-rays were caused to pass through an opening in 

 moistened cardboard (itself impermeable to them), and 

 thus a beam of the rays was got, which was caused to 

 pass through the aluminium prism and appeared to go 

 out from it by another face, making an angle with the 

 first, signs of dispersion by the p'ism being given in a 

 wav analogous to that of beams of light. The N-rays 

 were drawn out into a spectrum — they appeared to be 

 made up of various rays differing in wave-length. 

 Measurements of the length of wave arc given by M. 

 Blondlot in his papers. He endeavoured to get a 

 measurement of it by a sort of grating, and diffraction 

 fringes were obtained. The phenomena of Newton's 

 rings were also oljserved, and a whole series of 

 phenomena resembling those obtained with waves of light. 



Photography was employed to give a record of the 

 ch.anges of brightness produced bv the N-rays, and the 

 results got by Blondlot were confirmed by various ob- 

 servers in France. A remarkable thing about the re- 

 petition and confirmation of these experiments was that 

 thev occurred only in France. Observers in other 

 countries endeavoured to repeat Blondlot's experi- 

 ments, but with no satisfactory result. 



A strange development of the work r)f research 

 occurred when M. Blondlot published an account of a 

 new sort of N-rays, which, while resembling those 

 already described, had in many cases an inverse effect. 

 They diminished instead of increasing the brilliance of 

 a small electric spark when they fell upon it, and ihiv 

 caused a decrease in the phosphorescence of a sulphide 

 of calcium screen. These rays it was proposed to 

 call N'-Rays. Another property, both of these new rays 

 and the N-rays themseUes, was, that they become 

 stored up in substances on which they strike. .\ brick 

 exposed to the rays of the sun seems to absorb N-rays 

 and give them out afterwards. A curious effect next 

 noticed was that a screen feebly phosphorescing and 

 expr)sed to the action of the N-rays, when \iewed 

 normally by a person straight in front of it, :i()[)carc(l 

 more luminois than before, whilst itbecame less himirous 

 if looked at very obliquely or almost taneentially. 



Further researches were carried out on the trans- 

 parency of different substances to the N-rays, and they 

 were found to vary very much in this respect. .Silver 

 was foimd to be particularly transparent, and nickel 

 and some other metals opaque to these rays. 



The investigations were next taken up by v.-irious 

 physif)logists, especially M. Augustin Charpentier, of 

 Nancv, who described how streti'hefl muscle gave out 

 N-rays. f'hosphorescenco was produced on a screen 

 of barium platino-cy.-niidc bv means of a salt of r:idium, 

 and it was found that on bringing up various pf)rlions 

 of the human body to the screen the brilliancy of the 

 phosphorescence was increased. Mus;le and nerve 



