These particles, ‘‘emznations,”’ as they are /nown, are spoken 
of as “rays,” notwit cutendiag that they are in reality matter, 
or substance.* They are so light that, even after long periods, 
losing them. se emanations will accumulate in substances 
into sees they ical ees water, and wy ee Be gives 
off are from the radium, t 
still contains them and is giving them off, it is said to be radio- 
active, and it possesses, for the time, the valuable properties of 
the radium itself. This is especially true of water, as applied in 
medicine or to plants. It is to be noted that such rua 
n 
the substance ir in which oe areheld. On theo ee radium 
enters into with acids a: aH de compounds 
may be dis solved in water and other liquids. Such solutions 
e 
actually contain the radium metal. The bromide an e 
chloride of radium are the soluble compounds most used, the 
sulphate the principal insoluble 
e of different kinds, exhibiting different 
phenomena, having different velocities, penetrating different 
substances and for different distances and producing different 
effects on the bodies which they attack. They are distinguished 
as alpha, beta and gamma rays. 
On striking various substances in their flight, the ae a 
become lu w. 
mi. 
The rays also produce photographs in perfect darkness an 
trictly speaking, the term ‘‘emanations" appli nl 
aly ' 
the first rays (alpha rays) h the radium atoms. 
