278 Dr. 0, R. A. Wright on the Determination of 



whence acid of 27*0 grammes per 100 cub. centims. would 

 have a specific resistance of 1*47 x 10 9 at 18°. 



The value obtained by Paalzow for acid represented by 

 H 2 S0 4 , 14 aq. (Pogg. Ann. cxxxvi. p. 489, 1869), was 14157 

 times the resistance of mercury at 19°. This acid contains 

 28*0 per cent, of H 2 S0 4 , representing 33*7 grammes per 100 

 cub. centims., possessing the specific resistance 1*34 x 10 9 , or 

 about 8 per cent, higher than that found by Kohlrausch and 

 Nippoldt. 



On the whole the specific resistance of acid of the strength 

 used, viz. 27 grammes per 100 cub. centims., may be taken 

 as 1*4 ohm at 18°, whence the values of R for the four vol- 

 tameters, calculated from the dimensions of the columns of 

 fluid between the electrodes (§ 80), are : — 



13x1-4 



Voltameter No. 1 



No. 2. 



No. 3. 



No. 4. 



1-5 

 8x1-4 



1-0 

 6 x 1-4 



1-1 



17x1-4 



0-08 



ohms = 12*1 ohms. 



= 11-2 



= 7-6 



= 298-0 



Inasmuch as the value of the term OR is always small com- 

 pared with E, in the expression e = E — OR, a much greater 

 error in the determination of R than that included in the above 

 estimates will produce no material effect on the accuracy of 

 the determination of e. 







Voltameter No. 1 



, 





Surface of each electrode = 27*5 square centimetres. 



Mean Cur- 

 rent, inmi- 

 crowebers. 



Microwebers per 

 square centim. 

 of electrode 

 surface. 



Average 



value of E, 



in volts. 



CE, 

 in volts. 



e=E-CR, 



in volts. 



Eeinarks. 



1-6 



0-06 



1-480 





1-480 



No visible evolution 

 of gas. 



31 



0-11 



1-622 





1-622 





8-5 



0-31 



1-878 





1-878 



Distinct evolution of 



11-2 



0-41 



1-897 





1-897 



gas. 



25-1 



0-91 



1-971 





1-971 





62-8 



2-28 



2062 



•001 



2-061 





119-4 



4-34 



2-129 



•001 



2-128 





2167 



7-88 



2-218 



•003 



2215 



., 



310-0 



11-3 



2-274 



•004 



2-270 





543-7 



19-8 



2-333 



•007 



2-326 



„ 



