1886.] 



Conduction and Molecular Composition, fyc. 



277 



worthy that the maximum never exceeds that of the monobasic acids* 

 even in the case of phosphoric acid, which is universally regarded as a 

 tribasic acid, and that the monobasic hypophosphorus acid is the 

 strongest and the tribasic phosphoric acid is the weakest. In very 

 dilute solution phosphoric acid has less influence than even acetic 

 acid, according to Kohlrausch. 



It may be well also to quote Ostwald's numbers for sulphurous, 

 selenious, sulphuric and selenic acids. 



Table IV. 



V. 



Sulphurous 

 acid. 



Selenious 

 acid. 



Sulphuric 

 acid. 



Selenic 

 acid. 



2 





7-63 



92-7 



97 3 



4 



19-19 



9 73 



96-4 



103-2 



8 



25 43 



12 -70 



100-6 



109 -9 



16 



32 -79 



16-60 



107-4 



117-7 



32 



41-60 



21-73 



116-3 



127 -0 



64 



50-1 



28 -24 



127-3 



138 3 



128 



58 -9 



36 15 



139-2 



148-7 



256 



66-5 



45 11 



150-6 



157 9 



512 



72-5 



54 -27 



160 -9 



164-4 



1024 



77-1 



62-79 



169-1 



169-7 



2048 



80-4 



69-40 



174-4 



173-4 



4096 



83-6 



73-58 



177-1 



174-4 



8192 







176-9 



173 -4 



It will be observed that sulphuric and selenic acids are nearly alike 

 in behaviour, the latter being somewhat more active in concentrated 

 solutions ; it is noteworthy that of all the polybasic acids studied by 

 Ostwald, these are the only two containing a single negative radicle 

 (S0 4 ,Se0 4 ) which exhibit a conductivity in excess of that which cha- 

 racterises the monobasic acids. t 



The numbers obtained for sulphurous and selenious acids are 

 deserving of study. Sulphur dioxide is far from being a perfect gas 

 under ordinary conditions ; in the liquid state it is probably rich in 



* Ostwald appears to be of the opinion that if the dilution could be carried far 

 enough, a maximum conductivity = n -90 would eventually be attained in the case of 

 every »-basic acid. It appears to me that neither do his numbers warrant this — and 

 those here under discussion are an especially good illustration — nor is it likely to be 

 the case on my hypothesis. 



f Ostwald infers from the great increase in molecular conductivity that the 

 manner in which the acid is electrolysed varies with the strength of the solution ; 

 he supposes that in more concentrated solutions sulphuric acid is resolved into H and 

 HS0 4 , and that both atoms of hydrogen are split off only as the solution becomes 

 more diluted. This appears to me to be altogether improbable. 



VOL. XL. U 



