A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PIiATINUM 399
platinum black. The precipitated sulphide, indeed, contains some free platinum.
R. Bottger observed that if the precipitated sulphide be exposed to air, with constant
stirring, at 50° to 62°, it forms a black powder, which when heated to 100°
in a retort becomes violet-black. It is supposed to contain some oxidized plati?iic
sulphide. Its sp. gr. is 6-286 ; it has a sour taste ; forms sulphuric acid when treated
with water ; takes fire in air at 250°, burning with a hissing noise and violet flame,
with the evolution of sulphurous oxides ; and it becomes warm in a current of
hydrogen above 25° and decrepitates giving off hydrogen sulphide, and leaving a
residue of spongy platinum.
E. von Meyer doubted if the so-called " oxidized sulphide " contains platinic
oxysulphide, PtOS, but it may contain the normal platinum dihydroxysulphide,
Pt(OH)2S, or else (PtS)2O(OH)2. The former is said to be the first stage
in the oxidation of platinic sulphide ; and the platinic oxydihydroxydisulphide,
(PtS)2O(OH)2, or PtOS.\H2O, is produced when the dark brown precipitate
formed by hydrogen sulphide in hot soln. of potassium chloroplatinate, or
nearly neutral soln. of platinic chloride, and washing free from chlorides, is dried
on a water-bath, and heated, with frequent stirring, for about K) days at 70° to 100°.
The product is washed with hot water, and the treatment repeated. The product
is finally dried at 100° to 110° in a current of carbon dioxide. If the temp, of desiccation
is higher than this, oxidation occurs. When the powder is warmed in air,
sulphurous oxides are evolved, and platinum is formed. Hydrogen forms platinous
sulphide and water ; nascent hydrogen slowly forms hydrogen sulphide ; chlorine
in the presence of moisture forms sulphuric and hydrochloric acids ; cone, hydrochloric
acid reacts slowly without the evolution of chlorine, and after some time
the soln. contains a little sulphuric acid ; hydrogen sulphide forms water and
sulphur ; sulphur dioxide forms sulphur trioxide with the evolution of heat ;
sulphurous acid is slowly oxidized ; ammonia is rapidly absorbed with the evolution
of heat and the formation of water ; nitrous and nitric oxides do not react with the
oxysulphidc ; carbon monoxide forms platinous sulphide and carbon dioxide ;
oxalic acid slowly decomposes with the evolution of carbon dioxide ; methyl
alcohol is oxidized to formaldehyde ; ethyl alcohol becomes warm and forms aldehyde
and acetic acid ; toluene is partially converted into benzaldehyde ;
potassium permanganate is slowly reduced; and ferrous salts arc slowly converted
into ferric salts.
REFERENCES.
1 H. K. Adam, Trans. Qeol. Soc. South Africa, 33. 103, 1931 ; 34. 35, 152, 1031 ; B. Aulenkamp,
Zeit. Physik, 18. 7O, 1923 ; F. A. Bannister, Min. Mag., 23. 188, 1932 ; J. J. BcrzelniH,
Lehrbuch der Chemie, Dresden, 2. i, 180, 1826 ; Schweigger's Journ., 34. 22, 1822 ; W. BiHx. and
R. Juza, Zeit. anorg. Chem., 190. 161, 1930 ; R. Bottger, Journ. prakt. Chem., (1), 3. 274, 1834 ;
R. A. Cooper, Journ. Met. Min. Soc. South Africa, 28. 281, 1928 ; 29. 230, 1929 ; E. Davy,
Phil. Mag., (1), 40. 27, 209, 35O, 1812; H. St. C. Deville and H. Debray, Cotnpt. Rend., 89.
590, 1879 ; J. N. Frers, Zeit. Elektrochem., 40. 612, 1934 ; C. Himley, lAebig's Ann., 43. 152,
1842; V. N. Ivanoff, Chem. Ztg., 47. 209, 1923; W. Knop, Chem. Centr., (2), 4. 17, 1859;
H. G. Krall, Beitrage zur Kenntnis der Sulfide der JPlatin metalle, Darmstadt, 1933 ; H. .Londahl,
Lunds Arsskr., 27. 3, 1891 ; A. Mailfert, Compt. Mend., 94. 1186, 1882 ; F. Mylius and F. FSrster,
Ber., 24. 2441, 1891 ; L,. Pauling and M. L.. Huggins, Zeit. Kriet., 87. 205, 1934 ; G. Preiiner,
Zeit. anorg. Chem., 55. 82, 1907 ; J. Ribau, Compt. Rend., 85. 283, 1877 ; Bull. Soc. Chirn.,
(2), 28. 244, 1877 ; C. Ridolfi, Oiorn. Scienza Arti, 1. 24, 125, 1815 ; Quart. Journ. Science, 1.
259, 1816 ; Ann. JPhU., 7. 29, 1817 ; 13. 70, 1819 ; Phil. Mag., (1), 48. 72, 1816 ; (1), 53. 68,
1819 ; Schtoeigger's Journ., 24. 439, 1818 ; F. Rossler, Synthese einiger Erzmineralien und
analoger Metallverbindungen durch Aufiosen und Kristallisierenlassen derselben in gexchmolzenen
Metallen, Berlin, 1895 ; Zeit. anorg. Chem., 9. 59, 1895 ; R. Schneider, Journ. prakt. Chem.,
(2), 2. 164, 1870; (2), 7. 227, 1873 ; (2), 8. 29, 1874;