( 616 ) 
Efforts to obtain this compound, prepared from BaS and S, in a 
measurable form, and thus to obtain an argument in favour of the 
said view, in the event of an isomorphism between the two sub¬ 
stances, have been found so far unsuccessful. 
$ 11. In the electrolysis of a dilute solution of the potassium 
salt, in which the platinum-dish acted as the cathode and a disc¬ 
shaped platinum-electrode as anode, it looked as if tellurium was 
precipitated at both electrodes. The liberation of the black substance 
at the anode is nothing else than an oxidationphenomenon. 
The tension at the electrodes was 2.6 Volt, the current 0.05 Am¬ 
pere; the oxygen formed at the anode oxidises the liquid, so sensitive 
to oxygen, with separation of tellurium-sulphur complexes which 
partly stick to the anode and partly collect above the same on the 
liquid; if the current passes for some time the precipitate redissolves 
and the anode again turns bright. I have ascertained that the adhering 
precipitate contains tellurium as well as sulphur. 
On the other hand, the precipitation of a black substance at the 
cathode takes place continuously but very slowly; after twelve hours 
only a small portion of the salt, about one gram and a half in 50 cc 
of distilled water, had been decomposed by the current. This black 
precipitate has now proved to be pure tellurium and this observation 
would, therefore, go against the assumption that tellurium forms a 
constituent of the anion. This experiment, however, cannot be used 
as evidence against that view, since we know an analogous case in 
the electrolysis of sodium-sulphantimonate 1 ), where the antimony 
also proceeds, apparently, to the cathode, although it acts, in the 
salt, as a constituent of the anion. 
It has also transpired in these experiments that the metal does 
not wholly take part in the electric conductivity, but that in the 
electrolysis of the solution, the sodium sulphide is decomposed, and either 
the sodium liberated at the cathode, or the hydrogen which it causes 
to be evolved, precipitates the antimony by a secondary reaction. 
Only when a very little alkalisulphide is present, the anion "'SbS 4 
also moves towards the anode. Obviously, the explanation in our 
case is the same; the tellurium is formed secondarily at the cathode, 
whilst at the anode, as in the experiments cited, fairly complicated 
and somewhat obscure oxidationphenomena occur. In each case, 
this apparent contradiction does by no means prove the incorrectness 
of the view, that the said salts may be considered as derivatives of 
i) Ost und Klappboth, Zeitschr. f. angew. Ghemie (1900). p. 827. 
