ELECTRICITY. 85 



weight of ice into water, or that one gramme of radium bromide will 

 raise the temperature of 80 grammes of water one degree C. per 

 hour. 



Just as sun rays are made up of heat rays, light rays, and rays of 

 actinic power, so it has been found that there is a difference in the 

 rays of a radio-active body. There are at least three kinds, of which 

 the first group, called alpha rays, possesses remarkable penetrating 

 power and great photographic energy ; they are not deviated from 

 their path under the influence of a magnetic field, and resemble the 

 Rontgen rays in their action. The beta rays produce heat, are devi- 

 able under the influence of a magnetic field, and resemble cathode 

 rays. The third group gamma rays is easily absorbed. 



Of great interest is the physiological action of radium compounds 

 on the animal system. Radium bromide, even when enclosed in a 

 wooden or metallic box, brought near the closed eye causes the sensa- 

 tion of light. While nothing is felt when radium salts are brought 

 close to our body, yet a strong influence, similar to that of Rontgen 

 rays, is exerted upon the tissues. This is shown by the fact that days 

 or weeks after the body had been exposed to radium rays the skin 

 reddens and, if the exposure was of sufficient duration, sores and 

 ulcerations will form which require a long time for healing. A sealed 

 glass tube, containing a little radium bromide, when placed in a bowl 

 of water with small fishes will cause their death in a few hours. 

 Attempts are now being made to use radium rays like Rontgen rays 

 in the treatment of skin diseases, lupus, etc. 



When the apparently never-diminishing power of radium to give 

 out continuously light and heat was discovered, it appeared as if our 

 views regarding matter and energy were completely upset. A closer 

 investigation, however, has shown that this apparently unlimited 

 source of energy may be explained in a way conforming to our pre- 

 vious views. 



What is supposed to take place is this : All radio-active substances 

 send out with enormous velocity particles, called corpuscles, which are 

 a thousand times smaller than a hydrogen atom. This substance 

 which is thrown off, and which Crookes designates the fourth state of 

 matter, or radiant matte)*, is called emanation. The phenomena of 

 radio-activity, previously described, are due to these emanations 

 which cause a bombardment of everything lying in their paths. 



The discovery of radiant matter has modified our views regarding 

 atoms. It is now believed that the atom, as revealed in chemistry, is 

 a mass of a great number of small corpuscles which have come to a 



