. Light energy, its physics, physiological action and therapeutic applications . ows that the apparatus of Strutt fordemonstrating the positive charge of radium enclosed in aglass tube, may be modified so as to demonstrate also thenegative charge of the (3 radiation which penetrates the shown in the illustration, a glass bottle which may beevacuated contains the small glass tube b, which contains aradium-barium preparation, and is suspended by means ofthe quartz rod, a. Two quartz tubes, ax and a±, hold the hol-low lead vessel c, of a thickness of 2 mm., which is com- ^hys. Zeit., Mar
. Light energy, its physics, physiological action and therapeutic applications . ows that the apparatus of Strutt fordemonstrating the positive charge of radium enclosed in aglass tube, may be modified so as to demonstrate also thenegative charge of the (3 radiation which penetrates the shown in the illustration, a glass bottle which may beevacuated contains the small glass tube b, which contains aradium-barium preparation, and is suspended by means ofthe quartz rod, a. Two quartz tubes, ax and a±, hold the hol-low lead vessel c, of a thickness of 2 mm., which is com- ^hys. Zeit., March 15, and Elec. World and Eng., April 9, 1904. KAIHUM. 705 pletely insulated from b. Through b passes in spiral form theplatinum wire, f, which is connected to the electroscope, second electroscope, c, is fixed to the lead cylinder. Assoon as a good vacuum is reached, both electroscopesdiverge, d, with positive electricity, e, with negative electric-ity. It is also possible to demonstrate the current whichflows from the interior of the glass tube to the lead cylinder,. Fig. 44.—Paschens Modification of Strutts Apparatus. if both are connected by a wire. This current was first meas-ured by Wein. The divergence of e is always smaller thanthat of d, especially on account of imperfect absorption ofthe j3 radiation in lead of 2 mm. thickness. Within an hourthe electroscopes converge and the charges of their conduct-ors are neutralized, but the neutralization is not complete,both electroscopes showing afterwards a small positivecharge. Radium Radiation Complex.—The radiation of radio-active substances is a very complex one. There are threedistinct types of rays distinguished. These are called byRutherford the a7 /J, and y rays. 706 LIGHT ENERGY. In the first instance it was pointed out by Rutherford,that uranium possessed two distinct types of rays, a and (3,the former easily absorbed even by gases, while the latter arevery penetrating, and but little absorbed by gas. (i)
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