1.32 THE ALUMNI JOURNAL 



RADIUM MORE VALUABLE THAN DIAMONDS. 



Nothing which exists in such minute quantities as radium has 

 ever before been talked about so much. It was announced the 

 other day that a second gram of the mineral has been produced at 

 the Austrian government laboratory at Joachimsthal. It takes 

 more than four hundred grams to make a pound. After the Curies 

 had discovered radium, the Austrian government sent to them in 

 Paris by a special messenger two milligrams, or two-thousandths 

 of a gram. The mineral is so precious and so rare, and when not 

 properly protected can work such havoc, that none of it has ever 

 been sent through the mails or in any other way than by messenger. 

 It has to b.e combined with various other chemicals before it can 

 be conveniently used. Each radium preparation that is sent out 

 is incased in a small nickeled brass cartridge about one-third of 

 an inch in diameter. The bottom of the cartridge is filled with 

 lead, a square hole is made in the lead, and the radium preparation 

 is inserted. Then the cartridge is sealed with a mica cap, through 

 which the radium rays may operate. Every cartridge sent out is 

 registered and numbered, and none is sold save to learned men of 

 established reputation or to scientific institutions. Although 

 there is but a small fraction of a pound in existence, a pound at 

 the present prices would bring thirty-six million five hundred 

 thousand dollars. — Youth's Companion. 



THUNDER— WHAT IT IS. 



It used to be supposed that thunder is caused by the collapse of 

 the atmosphere upon itself in a partial vacuum created by the 

 electric spark of the lightning. This theory has no foundation, 

 according to Dr. Elihu Thomson, an authority on electricity. Doc- 

 tor Thomson's explanation is that the electric spark heats the at- 

 mosphere and causes its sudden expansion. This expansion sets 

 in motion atmospheric or etheric waves that produce sound when 

 they strike the tympanum of the ear. Doctor Thomson says also 

 that the rolling of thunder is not due to reverberation or echoes, but 

 to the length and the erratic course of the lightning spark, causing 

 the sound-waves to reach the ear as a continuous sound of vary- 

 ing intensity. — Exchange. 



