250 Luminosity of Gases through Electrical Discharges. 



Dividing T by the ratio of the cross section of the wider 

 tube to that of the narrower (1232), we get the increment of 

 temperature in the former, 



T 

 T ~~ 1232' 



Of a whole series of experiments I give the following five, 

 together with the values obtained from them for f and T: — 



p> 



y. 



cub. cent. 



z. 



Z. 



t. 



T. 



r. 



33 



0-09774 



350 



9 



3-93 



84340 



68-0 



3-3 





342 



8 



3-24 



80130 



65-2 



3-3 





348 



8 



3-52 



85560 



69-5 



2-66 





348 



10 



3-51 



86560 



70-4 



2-66 



>> 



338 



14 



4-35 



77250 



620 



As the mean temperature of the gas, before the passing of 

 the discharge, amounted to about 20°, the maximum tempera- 

 ture generated in the first tube was about 80-90°; and there- 

 with the gas was brightly luminous. 



It is necessary to remark that if alternating partial dis- 

 charges take place, the above temperature is still too high ; 

 and so it is when the discharges do not take place momentarily, 

 but last a certain time. Farther, since the gas constantly 

 becomes quite dark again between every two discharges, and 

 shines as brightly after the first as after the later ones, the 

 luminous appearances cannot be conditioned by heatings being 

 accumulated by the successive discharges. The temperature 

 62-70° is at all events not the lowest at which the gas appears 

 luminous ; for when the discharges of a Holtz machine were 

 conducted through a discharge-tube precisely similar to that 

 above described, the wider part of it appeared completely filled 

 with light, while the light in the narrower part was much 

 fainter than when the inductorium was employed. Exact calori- 

 metric measurements are, in consequence of the inconsiderable 

 production of heat, much more difficult to make with the 

 former than with the latter. 



The luminousness of the gas at so low a temperature during 

 the passage of electricity proves, when viewed in connexion 

 with the mechanical theory of gases, that the electric discharge, 

 independently of an augmentation of the vis viva of the pro- 

 gressive motion of the molecules by temperature, calls forth a 

 considerable heightening of the vis viva of the oscillatory 

 motion of the aether envelopes. 



To make use of the result here found for explaining what 

 goes on in the discharges in gases, and the nature of the elec- 



