1897J MICROSCOPICAL JOURNAL 353 



results of experiments, improvements were made in 

 nearly all the apparatus that was necessary, and quite 

 recently Dr. Macintyre of Glasgow, Scotland, has suc- 

 cessfully radiographed a calculus of the kidney en situ 

 which was subsequently found to have been precisely 

 delineated on the operating table. The same gentleman 

 has also successfully radiographed the ribs and vertebras 

 of adult men, obtaining at the same time faint outlines 

 of important organs, particularly the heart, in one case 

 of which an enlargement was distinctly portrayed, but 

 we are to have further developments yet. 



An interesting feature in connection with the Roent- 

 gen rays is its usefulness in detecting imitation gems 

 both diamonds and rubies being transparent to the Roent- 

 gen rays, while imitations in glass or paste are opaque to 

 them. Already a considerable use has been made of 

 this aspect. The process is also exceedingly useful for 

 examining the contents of postal packets, anything of a 

 metallic nature being at once detected if contained in a 

 wooden box. The only protection against such a revela- 

 tion is of course to pack goods in a metal box through 

 which the rays will not penetrate. It is rumoured that 

 instruments are already in use in the General Post Office, 

 London, for examing packets and the English War 

 Department has invested in a considerable number of sets 

 with a view to locating bullets on the battle field and so 

 saving the painful and tedious operation of probing. 



The Fluorescent Screen : — It was remarked that 

 under the iuliuence of the X rays certain chemical salts 

 have the power of becoming brilliantly illuminated and 

 of rendering visible objects which are opaque to the rays 

 that are interposed between the vacuum tube and the 

 fluorescent screen. For instance, if the hand be placed 

 between the fluorescent screen and the vacuum tube the 

 bones will be distinctly shadowed on the screen while the 

 flesh will be almost transparent, if the body be interposed 



