40 



Prof. E. Wiedemann on the 



Whole quantity of heat evolved. — The discharge-tube con- 

 sisted of two small bulbs of 12 millim. diameter, connected 

 by a capillary tube of 40 millim. length. 



^=9-75. 



p=V9. 



p=x. 





4- 



- 







+ 



- 







+ 



- 







mW ... 







2-92 



3-11 



3-08 





7-33 



6-59 





oW ... 







3-27 



3-52 



3-23 



343 



8-36 



6-86 



6-54 



F 







10-10 



5-0 



5-08 





12-31 







From these numbers we see that the total heating does not 

 alter much, although a small increase is perceptible when the 

 same electricity is transmitted in a decreasing number of dis- 

 charges. The removal of resistances corresponds to the 

 including of an air-spark, but the heating is certainly not 

 greater in proportion to the smaller number of discharges. 

 The same considerations which I have already stated* there- 

 fore hold good. 



Heat evolved in the capillary connecting tube. 

 (1) Heating in a capillary of 1 millim. diameter : — 



p 



= 12-9. 





p=2. 



p = x. 



p=xx. 





4- 



- 



+ 



— 



+ 



- 



+ 



— 



mW ,.. 



10-8 



13-0 



4-5 



5-35 



2-52 



1-90 



20 



1-46 



oW ... 



11-5 



9-7 



5-13 



6-10 



1-73 



2-64 



1-8 



1-95 



F 











3-85 



4-20 



3-36 



4-0 



Here also the heating with and without resistances is nearly 

 the same, and again the heating increases somewhat as the 

 number of discharges decreases. This is pretty regularly the 

 case when we consider only the negative discharges ; with the 

 positive on the other hand, the minimum heating is at low 

 pressures without a resistance. The positive discharge ex- 

 hibits therefore here, as in many other cases, a less regular 

 behaviour. 



(2) Heating in a tube of 4 millim. diameter : — 



p = 12'7. 



^=6-4, 5-9. 



^ = 6-4,5-9. 



mW ... 

 oW ... 

 F 



-r 

 8-3 



111 



H 

 35 

 4-5 



h 

 6-8 



6-4 

 6-4 



6-3 

 9-0 



* Wied. Ann, xi. p. 218 (1883). 



