310 SCIENCE PROGRESS. 



formation of sodium tetrathionate and sodium iodide, the 

 action being expressed by the equation — 



NaO'SO.-SjN'a + I 2 + NaS-S0 2 -0Na = 

 NaO-S0 2 -S-S-S0 2 -ONa + 2 Nal. 



An apparently very similar synthesis by means of electro- 

 lysis has been performed by H. Marshall, who found that 

 a concentrated aqueous solution of potassium hydrogen 

 sulphate KHS0 4 when electrolysed yielded at the anode 

 a new compound, potassium persulphate K 2 S 2 O g . In all 

 probability the ions in a strong solution of potassium 



hydrogen sulphate are K and H0'S0 2 *0*, so that at the 

 anode we have on the discharge of the negative ion the 

 following synthetic action : — 



HOS0 2 0+-OS0 2 OH = HOS0 2 OOS0 2 OH. 



The persulphuric acid thus formed falls out of the solu- 

 tion as potassium persulphate, which is only slightly soluble 

 under the conditions of experiment. We cannot state with 

 certainty that the scheme given above represents the pro- 

 cess of formation of persulphuric acid, as we are as yet too 

 little familiar with the reaction, but in any event the 

 electric current has here brought into existence a more 

 complex compound from a simpler one, and we are thus 

 entitled to regard the case as an interesting and novel 

 electrosynthesis. 



BIBLIOGRAPHY. 

 KOLBE. Liebig's Annalen, lxix., 257, 279. 

 Kolbe and KEMPF. Jour, fur prakt. Ckemie, iv., 46. 

 Brazier and Gossleth. Liebig's Anna/en, lxxv., 265. 

 KEKULE. Liebig's Annalen, cxxxi., 82. 

 Jahn. Wiedemann s Annalen, xxxvii., 408. 

 Crum Brown and Walker. Trans. Roy. Soc. Edin., xxxvi., 



211, and xxxvii., 361 ; also Liebig's Annalen, cclxi., 107, and 



cclxxiv., 41. 

 Marshall. Jour. Chem. Soc., lix., 771. 

 Murray. Jour. Chem. Soc., lxi., 10. 

 Mulliken. Anter. Chem. Jour., xv., 523. 

 Walker. Jour. Chem. Soc, Ixiii., 495. 



James Walker. 



