1902.] TROWBRIDGE — GASES AT HIGH TEMPERATURES. 139 



bored, so to speak, in the air, tlirough which, by means of water 

 vapor, what we call electricity passes with a loud explosion. I wish 

 to emphasize this fact in speaking of the scientific results which I 

 have reached with this large electrical plant. I believe that I have 

 proved that water vapor is essential for the passage of electricity 

 through the air or gases. Just as a certain degree of moisture is 

 necessary for chemical reactions, so is water vapor essential for the 

 discharge of electricity through gases. I believe that we have never 

 been able to obtain a perfectly dry gas ; and if we should succeed 

 in the future, such a gas would be a perfect electrical insulator. 



Since the time of Franklin, the subject of spectrum analysis has 

 been developed. He could study electricity only by means of his 

 eyes. With the spectroscope, however, we now see instead of a 

 blinding flash of white light, lights of many colors — in other 

 words, a spectrum extending from red light to violet light, traversed 

 by many bright lines which are due to the vibrations of the mole- 

 cules of the components of the air. These molecules are invisible to 

 us until revealed by electricity. The large storage battery I have 

 had constructed enables us to explore a new field in electrochem- 

 istry, revealed by the motions of the smallest particles of matter in 

 the world ; particles which are everywhere about us, but are only 

 evident when agitated by a discharge of electricity. I can surely 

 claim to have subjected gases to the highest temperature that has 

 been hitherto reached with this interesting result, that the spectra 

 of oxygen, hydrogen, nitrogen, the main components of the air, 

 contain the same spectrum, which is that of water vapor. By 

 modification of the strengtli of the discharges, one can pass from 

 the blue spectrum of argon to the red spectrum of this gas, which 

 was discovered by Lord Rayleigh, even in tubes filled with hydro- 

 gen. This result is accomplished by a powerful dissociation of 

 the small amount of air which is always present in glass tubes, 

 even when great care is taken in preparing the hydrogen. I have 

 obtained many such singular dissociations in hydrogen tubes which 

 have been unsuspected. 



Another important fact has been revealed by the passage of pow- 

 erful discharges through glass tubes filled with rarified gases. I 

 have discovered a rate of molecular vibration to which the photo- 

 graphic plate is apparently inactive. All gases give bright lines in 

 their spectra, and consequently these bright lines are dark lines on 

 the photographic negative. I have discovered dark lines in the 



