268 J SAKURAI; 



gives increasingly too high values of /-*„. Taking this fact into con- 

 sideration and comparing the above numbers with those obtained for 

 amidosulphonic acid — 



u = 32 64 128 256 512 1024 



100m = 79.09 86.87 91.42 96.04 96.79 97.99, 



it becomes evident that amidosulphonic acid is much stronger than sul- 

 phurous acid. This conclusion, drawn from the study of the electric 

 conductivity of amidosulphonic acid, is interesting, from the fact that 

 the influence of the NH 2 group upon the strength of organic acids 

 generally is quite of the opposite character. Thus, from the data 

 given by Ostwald (Zeit, physih. Chan., 1, 74 [1887]), I have 

 calculated the following values of 100 m for benzene-sulphonic acid : — 



v = 32 64 128 256 512 1024 



100m=90.91 93.95 96.15 98.15 99.61 100.00. 



Benzene-sulphonic acid is thus one of the strongest acids, whilst 

 its amido-derivatives are far below it in strength, as may be seen 

 from the following numbers (Ostwald : Zeit, physik. Chem., 3, 406 



100 m. 



v o. Amidobenz. m. Amidobenz. ^>. Amidobenz. 



sulphon. acid. sulphon. acid. sulphon. acid. 



32 — — 12.79 



64 36.6 10.25 17.52 



128 47.1 14.26 23.80 



256 58.5 19.70 31.80 



512 69.8 26.55 41.60 



1024 80.0 34.70 53.00. 



Again, benzoic acid is stronger than its amido-derivatives, and 

 acetic acid, though itself a very weak acid, is yet incomparably 



