396 M. BuflF on the Law of Electrolytic Cmiduction . 



of K. When Cr^ 0^ was still further electrolysed, as is the case 

 with AP Cl^, then in this new decomposition Cr^, or two atoms of 

 chromium, would have the same signification as three atoms of K. 

 Unfortunately I could not examine oxide of chromium in a fused 

 condition. I believe, however, that the deportment of chloride of 

 aluminium is sufficiently convincing. The electrolysis of higher 

 degrees of combination is as equally reconcileable with the fun- 

 damental law of electrolysis as in the case of chemical combina- 

 tion the multiple proportions are with the law of equivalents . 



Sevei'al of the bodies examined, as protochloride of copper, 

 chromate of potash, or chloride of lead, I found to be sufficiently 

 good conductors at ordinary temperatures, to be able to measure 

 this capacity by a precipitate of silver, which undoubtedly was 

 very small. By heating without fusion, the conductivity quickly 

 augmented, and certainly without any real decomposition taking 

 place. When a platinum wire surrounded by several layers of 

 solid and fused chloride of lead was dipped into a liquid chloride 

 of lead, which was not much or not at all heated above the point 

 of fusion, a new layer of the chloride naturally deposited itself 

 round the wire. If, however, by the immersion of the wire, 

 as the pole of a battery, a strong electric circuit was at the 

 same time closed, the temperature of the substance was so raised 

 by the current passing through it, that it was fused off in a few 

 seconds. If the chloride of lead could retain such a conductive 

 power in the liquid state also, in its electrolysis a great precipi- 

 tate must show itself. This, however, did not occur. Small 

 differences, which certainly occur, and which were also observed 

 in your electrolyses, stand in no relation whatever, and may be 

 referred to other causes, — for example, to the no small conduc- 

 tivity of the hot sides of the glass vessel. With chromate of pot- 

 ash and protochloride of copper, I found the same as with chlo- 

 ride of lead. The copper salt in its solid state showed itself so 

 sensitive to changes of temperature, that even by the heat of the 

 hand the conductivity was considerably increased. Still the 

 electrolysis gave a satisfactory result. From these experiments 

 we may certainly conclude as to the deportment of other electro- 

 lytes ; and it is perhaps not too bold to assume that even oxide 

 of iron and sulphide of lead, if they could be obtained in a state 

 of fusion and subjected to a current, would conduct only so far 

 as they are decomposed. 



I remain, dear Sir, 



With high esteem. 



Your obedient Servant, 



H. Buff. 



