MOLECULAR CONDUCTIVITY OF AMIDOSULPHOXIC ACID. 267 



9 181 [1892]) that sulphurous acid, in point of electric conductivity, 

 behaves as a monobasic acid, its ions being H and S0 3 H. It is, 

 therefore, possible to obtain a knowledge of the influence of the 

 replacement of if by NH. 2 upon the strength of the acid, by com- 

 paring together the values of 100 m of sulphurous and amido- 

 sulphonic acids. Determinations of the electric conductivity of sul- 

 phurous acid, as well as of metallic sulphites, are, however, attended 

 with considerable inaccuracy, owing to the unavoidable and rapid 

 oxidation occuring during the determination. The following are the 

 numbers obtained by Barth (loc. at.) at 25°: — 



v= 32 64 128 250 512 1024 

 Sulphurous acid H,S0 3 H ... 177.5 214.9 248.5 279.0 303.3 324.7 

 Hyd. sod. sulphite Na,SO^H 80.9 84.7 88.7 92.5 95.8 98.8. 



The difference /hm—faa for the sodium salt, instead of being 

 tbout 10, is as high as 17.9, this error arising from the partial oxida- 

 aion of the sulphite into sulphate. The numbers obtained by Barth 

 are, therefore, admittedly too high, the higher as the solution is the 

 more dilute. AVe have, therefore, no means of calculating exactly 

 the velocity of migration of the anion, SO à H, but it may be approxi- 

 mately taken to be (80.9+ 14)-49.2 = 45.7, SO. 9 being the value of 

 /% for the sodium salt, 14, Bredig's constant for this dilation, and 

 49.2, the velocity of migration of the kation, Xn. The approximate 

 molecular conductivity of sulphurous acid at infinite dilution is, 

 therefore, /^ = 32o + 45.7 = 370.7, and the values of 100 /4,//* x for this 

 acid at the respective dilutions are — 



17=32 04 128 250 512 1024 



100 wi=47.88 57.97 07.04 75.20 81.82 87.59. 



The increase of dissociation with dilution, as thus calculated, is 

 admittedly too great, inasmuch as the oxidation of sulphurous acid 



