DISCOVERY AND INVENTION 



653 



What is an odor? Is it an emanation 

 of material particles into the air, or is it 

 a form of vibration like sound? If you 

 can decide that, it might be the starting 

 point for a new investigation. If it is an 

 emanation, you might be able to weigh it ; 

 and if it is a vibration, you should be able 

 to reflect it from a mirror. You can re- 

 flect sound and light and heat, and I have 

 even warmed my hands at the reflection 

 of a fire in a mirror. Not a glass mirror, 

 for glass is opaque to radiant heat. A 

 sheet of transparent glass makes a fine 

 fire-screen. You can see the fire through 

 it, but it cuts off the heat. When you try 

 to reflect it from an ordinary looking- 

 glass, the heat has to go through the glass 

 in order to reach the reflecting surface 

 behind and then pass through the glass a 

 second time in order to get out. Take a 

 sheet of polished metal — tin-foil will 

 do — or any metal with a bright and shiny 

 surface and you can reflect heat from it 

 with ease. 



Can you reflect a smell or measure its 

 velocity of transmission? If you can do 

 those things you will be well advanced 

 on the road to the discovery of a new 

 science. 



THE SMEXL OF TEXLURIUM 



Well, that reminds me of a discovery 

 that started with a smell. We have a 

 very rare elementary substance known as 

 tellurium, and when you melt it with a 

 blow-pipe it gives off a smell. We can't 

 measure it, nor even describe it ; but if 

 you have ever smelled it you will know 

 it ever after. There is nothing in heaven 

 or on earth that smells like that. 



Now, you know it is the object of 

 many chemists and scientific men to turn 

 their discoveries to some practical use. 

 They try, through chemical and other 

 means, to convert waste products, for ex- 

 ample, into useful things. Indeed, the 

 utilization of waste products is a charac- 

 teristic of the age in which we live. 



Just think what they have done. Here 

 is a gas manufactory consuming coal. 

 After the gas has been produced we have 

 left upon our hands ashes and clinkers 

 and a lot of evil-smelling tar. Well, the 

 chemists go to work and out of that tar 

 they make the most delightful perfumes 



for scenting handkerchiefs, and nice 

 sweet essences for flavoring puddings, 

 and the most beautifully colored dyes, all 

 made from coal-tar. 



Now, there was a distinguished chem- 

 ist who thought he saw a chance of mak- 

 ing something valuable out of the waste 

 products obtained in the manufacture of 

 sulphuric acid. Some of the powder he 

 obtained he heated with a blow-pipe, and 

 at once perceived the characteristic smell 

 of tellurium. Here, he thought, was a 

 rare and valuable element contained in a 

 common and cheap by-product and it 

 might pay to extract it. He then applied 

 various chemical tests, but could get no 

 other indication of the presence of tel- 

 lurium excepting the smell. All the re- 

 actions declared there was no tellurium 

 there. 



He did not stop with this observation, 

 but followed it up and began reasoning 

 about it. If, he thought, there is no tel- 

 lurium here, there is certainly something 

 that has a smell very like it, and I know 

 of no other substance on earth that has a 

 smell like that. Perhaps there may be a 

 new substance here, not yet discovered, 

 which resembles tellurium, at least in the 

 smell. 



He knew that he was working with a 

 regular conglomerate or mixture of all 

 sorts of materials, many of which he 

 could identify. He then extracted from 

 the mass all the materials he knew were 

 there to see if there was anything left ; 

 and, sure enough, a residue appeared 

 which turned out to be, as he had sus- 

 pected, a new elementary substance not 

 heretofore known to man. 



SELENIUM FOUND 



He termed this substance selenium be- 

 cause it resembled tellurium. The word 

 selenium, you know, is derived from a 

 Greek word meaning the moon, and tel- 

 lurium comes from the Latin — tellus, the 

 earth. The two substances were not iden- 

 tical, but were related to one another as 

 the moon is to the earth. 



Selenium was found to resemble black 

 sealing-wax in appearance. It had a 

 beautiful, black, glossy surface, and in 

 thin films was transparent, showing ruby 

 red by transmitted light. In this, its vit- 



