A Comprehensive Treatise on Inorganic and Theoretical Chemistry

no INORGANIC AND THEORETICAL, CHEMISTRY
traces of ruthenium, rhodium, palladium, and iridium on the hydrogen overvoltage
of platinum; and A. Gorodetzkaya and B. Kabanoff, the contact angle of the hydrogen
bubbles. N. Thon electrolyzed soln. of platinum salts with an electrode of rare
gas. N. Koboseff and N. I. Nekrassoff studied the emission of electrons during the
cathode polarization of platinum ; M. O. Charmandarian and B. I. Pervuschin,
the electrokinetic potential ; and R. Kohler, the effect of occluded hydrogen on the
reduction potential. C. O. Henke and O. W. Brown observed no relationship
between the catalytic activity of metals and their over voltages ; A. Sie verts and
P. Luegg, no effect of a-naphthoquinoline on the potential of hydrogen separation
on platinum ; and J. M. Ort and M. H. Roepke, the effect on soln. of sugar.
A. Coehn and Y. Osaka observed that the oxygen overvoltage of a plain
platinum anode is very high, for it is 1*67 volts, and that of a platinized platinum
anode is 1-47 volts. G. Tammann and F. Runge, P. S. Tutundzic, J. A. V. Butler and
co-workers, T. Onoda, S. Glasstone and A. Hickling, A. D. Garrison and J. F. Lilley,
II. M. Cassel and E. Krumbein, E. Tommila, and F. Glaser made observations
on the subject, and F. Haber reported the formation of some hydrogen dioxide
at the anode. F. Forster and A. Piguet found that the rate of increase of the
anode potential of platinum in 2iV-KLOH, or 2AT-H2SO4, is greater than it is with
palladium, iridium, iron, and nickel. The subject was studied by V. V. Pitscheta,
A. Rius, and F. P. Bowden. The electrolytic valve action was studied by E. Newbery.
L«. W. Haase observed that the oxygen depolarization current is favoured by
darkness. A. P. Rollet, and J. W. Shipley and C F. Goodeve studied alternating
current electrolysis with platinum, copper, and silver electrodes; and V. Cupr,
oxidation-reactions at the platinum anode.
L. Arons emphasized the fact that with platinum electrodes it requires a very
feeble e.m.f. to develop hydrogen and oxygen in the electrolysis of suitable aq.
soln. D. Reichinstein observed that the formation of hydrogen on a platinum
cathode proceeds more rapidly than is the case with oxygen on a platinum anode
under quite similar conditions. A. Coehn found the reversible production of
hydrogen on platinized platinum is 1-08 volt. K. Bennewitz observed that the
decomposition potential of sulphuric acid with rotating platinized electrodes is
1-46 volts. The decomposition at this potential is supposed to occur only at certain
points on the electrode, and to become general at a voltage between 1*50 and 1*63.
Previous investigators observed breaks at 1*47 and 1-95 volts in the curves representing
the variation of the voltage and the change of e.m.f. in the electrolysis of
sulphuric acid, but these breaks were not observed with the rotating electrodes.
There is a break at 2-20 volts with a soln. of alkali hydrosulphate in cone, sulphuric
acid -which is supposed to represent the formation of persulphuric acid : 2HSO4'
^H2S2O84-20. The break at 1-08 volts was observed only with stationary
electrodes, and it is connected with the passivity of the metal. There is a break
at 0*76 volt with both stationary and rotating electrodes, and it is supposed to be
connected with the formation of platinum oxides or hydroxides, and not with
passivity. G. Armstrong and co-workers studied the subject. K. Bornemann
found that platinum electrodes in A^H2SO4 with hydrogen dioxide furnish a
curve with a break at 1-20 to 1*22 volts, and with electrodes which have been
heated to redness, at 1-06 to 1-08 volts. A. Mazzucchelli and C. Barbero also investigated
the potential with soln. of hydrogen dioxide ; and O. Mumm, and F. Forster,
the potential of ozone formation. The decomposition voltage curve of hydrochloric
acid was discussed by E. Miijler, R. Luther and F. J. Brislee, and E. Bose. According
to G. Pfleiderer, when a dil. soln. of hydrochloric acid is electrolyzed with
fresh platinum anodes, and the current is kept constant, the potential rises gradually
from 1 -4 volts to about 1 -9 volts, when oxygen is given off freely. The oxidation
of the platinum may be due to the influence of hypochlorous acid formed by the
action of chlorine on the water. Both oxygen and chlorine are formed, and the
formation of oxygen can be regarded as a secondary phenomenon : 2Cl2*-f-2H20
—4ClH-J-O2 ; and D. Macaluso also studied the behaviour of platinum in a soln.