M. BuflF 071 the Law of Electrolytic Conduction. 395 



Last winter I was able, through friendly assibtance, to ex- 

 amine the electric deportment of a number of compound bodies. 

 In your ' Experimental Researches ' you had stated that higher 

 compounds, such as sulphuric acid, when they enter into further 

 combinations, do not suffer a primary decomposition by the 

 electric cmTcnt. I have satisfied myself in the first place that 

 the few exceptions to this rule which it was believed had been 

 discovered, do not exist. My mode of operation consisted in 

 decomposing the fluid, in a V-shaped tube, under circumstances 

 which permitted me to recognize the direction in which the ions 

 move towards the electrodes. In this way it was found that 

 chloric, iodic, chromic, and manganesic acids and salts are decom- 

 posed exactly in the manner which Daniell proved regarding 

 nitric and sulphuric acid. 



Of pure specimens of the higher degrees of combination we 

 have unfortunately but a limited choice. Many of them are too 

 refractory, or suffer decomposition at high temperatures ; others, 

 which are easily obtained in a liquid state, ax'e not conductors. 

 Nevertheless some sufficiently fused Cu^ CI was found to con- 

 duct well, and according to the results of several analyses, spht 

 itself into Cu^ and CI. In like manner, basic pi'otonitrate of 

 mercury contains for 2Hg one 0. The alcoholic solution of sub- 

 limate, when free of hydrochloric acid, conducts very badly, but 

 is decomposed into Hg^ CI and CI; in which case, however, I 

 will not venture to decide whether or not the Hg^ CI be formed 

 by secondary combination, or by the action of Hg upon the sur- 

 rounding HgCl. In all these cases, whether a simple or com- 

 pound atom was liberated, the amount of decomposition agreed 

 very well with the indications of the voltameter. As voltametric 

 medium, I soon chose the precipitate of silver from nitrate of 

 silver. The latter serves best when only feeble currents are to 

 be obtained. 



Anhydrous chloride of aluminium, easily fusible, and a good 

 conductor, was decomposed into chlorine and pure aluminium. 

 Molybdenic acid and vanadic acid were decomposed, so that for 

 one atom of MO'^ or VO^ we had one of 0. Not a trace of metal 

 was obtained at the same time. 



Acid chromatc of potash is known to contain the second atom 

 ofacid free from water. Fused, it conducts very well. In this case, 

 according to several analyses conducted with care, the current 

 divides itself between the free acid and the salt. The first was 

 decomposed into Cr^ O^ and 0^, and the last into K and CrO"*. 

 The sum of both decompositions agrees in the most exact manner 

 with the electrolytic law, when we assume that in the decomposi- 

 tions and compositions proceeding in different directions, an atom 

 of Cr'O^ carries the same quantity of electricity as three atoms 



