378 Prof. E. Wiedemann on the Behaviour of Gases 



the water was 9*4 centiins., its diameter 0'58 millim. The 

 water-equivalent of the calorimeter and water was 16'2. 

 The elevations of temperature (reduced, as usual, to a gal- 

 vanometer-deflection of 100 millims. and one minute) were: — 



p 



+ 



15*5 



1-09 

 050 



1-01 

 0-37 



The mean number of discharges was 60,000 per minute 

 when j?= 15*5 millims., and 144,000 when p = 5*5 millims. 



Next, the deflection of the galvanometer must be reduced 

 to definite units. With a thermo-current produced by a 

 copper-silver element whose points of junction were main- 

 tained at 13° and 29°*2, and resistances introduced of the 

 values in Siemens's units 0, 1, 2, and 3 respectively, the galva- 

 nometer gave deflections of 122, 37, 21, and 15 millims. From 

 these numbers, and from the distance of scale and mirror, viz. 

 189 centims., the resistance of the element and of the galvano- 

 meter is found to be 0*43 Siemens. 



[The intensity of the current corresponding to a deflection 

 of 100 millims. is 1*000336 Siemens-Daniell unit. The num- 

 bers given in the original paper are erroneous through a mistake 

 in the determination of the galvanometer-constant. Accord- 

 ingly the numbers in the foregoing part have been corrected. 

 — E. W.] 



If now we denote by t the rise in temperature of the calori- 

 meter, W its water-equivalent, I the length of the portion of 

 the capillary tube included, then the quantity of heat evolved 



Wt 

 per unit length B = -y-; and if we assume that this is pro- 

 portional to the quantity of electricity transmitted e, we obtain 

 for the quantity of heat X produced by unit quantity of elec- 

 tricity in unit time per unit length, 



„ Wt 

 The values of X in our experiments are as follows : — 



p 



+ 



- 



155 

 5-1 



3200 

 2636 



2966 

 1962 



in which the centimetre is the unit of length, the gramme the 

 unit of weight, the minute the unit of time, and the unit quan- 



