34 (98) Society for Experimental Biology and Medicine. 



tion and are promptly removed from the same. In this process 

 the whole radium coating is covered with a very thin film of col- 

 lodion. In the course of a few days this film of collodion becomes 

 so tough that it will strongly resist destruction, even when consid- 

 erable force is used, thus affording ample protection for the under- 

 lying radium. This thin film, however, permits the alpha rays as 

 well as the emanations to penetrate freely. In the preparation of 

 these coatings both the radium and the collodion solutions are 

 colored with an anilin dye. This is done to show the part that 

 has been coated. Besides, if the radium happens to be removed 

 by accident or otherwise, as by scraping, etc., disappearance of the 

 color from the damaged places makes such removal evident. 



The great difference between radium used in containers, com- 

 posed even of exceedingly thin aluminium, and radium used in the 

 form of the coatings here described, was demonstrated. Thus, in 

 their relative influences on the electroscope, it was seen that a 

 delicate rod coated at its tip with radium bromid of 10,000 activity 

 and, holding, therefore, very little radium, compared very favorably 

 in its effects with a gram of radium bromid of 10,000 activity in a 

 glass tube, or with 10 mg. of radium bromid of 1,000,000 activity 

 in a very thin aluminium tube. 



As is well known, when we observe the effect of uncovered 

 radium upon a zinc sulfid screen, such as is shown in the spinthari- 

 scope of Crookes, we see a large number of brilliant scintillations. 

 It has been proved conclusively that these scintillations are pro- 

 duced solely by the impact of the alpha rays upon the zinc sulfid. 

 If what has just been said is correct, that is, that the alpha rays 

 can penetrate the collodion coating of the author's celluloid rods, 

 discs, etc., then the latter should yield evidence of these scintilla- 

 tions when placed upon a zinc sulfid screen. Such scintillations 

 were abundantly demonstrated with various forms of the coatings. 



The radium coatings make it possible to apply radium directly 

 to practically any part of the body. The radium thus applied 

 would be practically equivalent in radioactive effects to the same 

 amount of uncovered radium in the same thin layer. Any instru- 

 ment could be conveniently coated with radium at a proper place, 

 by the method indicated, and the radiations could be brought into 

 action wherever desired. 



