Ixxxii. PRESIDENT'S ADDRESS. 



of half-an-hour at present required to send a half-plate photo- 

 graph 500 miles is too great for practical use. This is effected 

 by a ray of light passing through the photographic film and 

 impinging on a selenium cell, in which the resistance varies 

 according to the light intensity. Wireless telegraphy has been 

 much used in the Russo-Japanese War, and messages have been 

 conveyed over a distance of 2,500 miles. A very important 

 modification has lately been discovered by which the message 

 can be sent in one direction only, thus greatly diminishing the 

 danger of its being read in unwished-for quarters. Wireless 

 telegraphy is now under Government control in this country. 



CHEMISTRY. 



In chemistry the progress of organic synthesis continues, so 

 that we now have 200 or 300 organic products, which can be 

 built up synthetically by the chemist, though nothing approach- 

 ing a living cell has yet been made. That wonderful substance, 

 radium, with its emanation and various rays, occupies much 

 attention, and perplexes scientific men, some of whom incline 

 to the idea that the elementary substances themselves are 

 unstable, and may verify the dream of the alchemist by mutual 

 change ; and that the ultimate atoms of matter, so long 

 considered indivisible and indestructible, are merely various 

 forms of electric energy. After this it seems feeble to speak 

 of the discovery of three new elements in the past year, 

 berzelium, carolinium, and "new" thorium. Who could have 

 thought that the twentieth century would have begun by 

 upsetting so many long-established fundamental ideas ? A 

 metal, suitably named Tantalum, which has been known to 

 exist for more than 100 years, has only recently been prepared 

 in a pure form, and bids fair to become of great importance, 

 both for electric lighting and in other ways. Though extremely 

 ductile, it is so hard as to be scarcely affected even by the 

 diamond, which opens out a vista of immense possibilities. 



