PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. VI. 719 



the back. This experiment was made in varied forms more than 20 times with in the main the 

 me result. 



My explanation of the thin, diffuse deposit upon the 200 plate is that after the positive rays have 

 "st their velocity, they are drawn in electrostatically towards the plate, evenly right round it. 



A reservation must be made here, however, as there is a possibility that this explanation of the 

 , c// coating of palladium round the 200 plate is incorrect. 



The cathode rays, as might be expected, were drawn in upon the o plate. Rays such as these 

 jukl, as we know, cause an already produced precipitation of palladium to decompose again. It may 

 ( ii tore be imagined that eventually it was the palladium corpuscles detached from the cathode-rays and 

 i-ed for the second time, that were positive and were thus evenly drawn in towards and all round 

 le 200 plate. 



The experiments that were made to show that metal rays went through aluminium foil, were car- 

 d out in the following manner. 



A small cassette of brass had 4 small holes, 0.5 mm. in diameter bored side by side in the lid. 

 ut of the thinnest aluminium-foil of about one-thousandth part of a millimetre, small entire portions were 

 arched for with a microscope, and laid in one, two, three or four layers over the four holes. Under 

 c whole there was a sheet of glass. A little steel magnet was placed behind the cassette, for the pur- 

 ise of deflecting ordinary cathode-rays from the cathode, which was placed at a distance of 20 mm. 

 ^lit in front of the holes in the cassette. 



After the discharge had been going on one or two hours, the cassette was opened and the sheet 



glass studied. The precipitation of metal through the foil was not so considerable that it could be 



i n without doubt with the naked eye; but by breathing on the glass a sharply-defined, well-marked 



ml appeared beneath the hole with one layer of aluminium-foil. Under the hole that was covered with 



o layers there also appeared a distinct spot; under that with three layers the deposit could scarcely 



distinguished; but under the hole that was covered with four layers, not even traces were found in 

 iv case. 



Since cathode-rays as stiff as those in these discharges would easily pass through even four layers 



such thin aluminium-foil, and as these rays in most cases were deflected with a steel magnet, it must 



obably be assumed that they are metal rays that have penetrated through the foil, but in very different 



:grees through the four holes. These experiments, however, will be continued, as also those that have 



en made for the determination of charge and mass of the metal corpuscles. 



There is yet another point in these experiments that will be touched upon here. It has been 

 entioned above that under certain conditions marked oscillations might occur in an oscillatory circuit 

 >nnected(') in parallel with the anode and cathode in the vacuum-tube as poles. 



It appears that the disintegration of the cathode is much greater under these conditions, and that 



this case thin, luminous pencils of rays are emitted by the cathode. At the foot-points of these pencils 



particular, the cathode-material becomes so greatly disintegrated, that under the microscope the surface 



' the cathode gives the impression of having been corroded with a quantity of tiny cavities. It also appears 



at it is not necessary to keep the temperature so high as that given above in order to obtain a powerful 



:velopment of positive metal rays from the cathode when it is connected with such an external oscillatory circuit. 



The rays that have hitherto been called a-rays, consist, as is well known, of positive helium atoms, 

 ected with enormous velocity from a radio-active substance, e. g. radium. 



There seem, from the discoveries here mentioned, to be good grounds for extending the conception 

 rays to include rays formed of all positive atoms that are ejected with such velocity as to give rise 



the properties of a-rays. 



(') I.e., C. R., March 17, 1913. 



