A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM 59
KoIl. Zeit., 1. 162, 1907 • 2. 144, 1909 ; T. Svedberg and K. Inouye, ib., 9. 154, 1911 ; O. Teague
and B. H. Buxton, Zeit. phys. Chem., 62. 292, 1908 ; C. Thomas, KoIl. Zeit., 9. 19, 1911 ;
P. C. L. Thorne, A. R. Kennedy and A. H. Holloway, ib., 44. 190, 1928 ; A. Voet, Trans. Faraday
Soc, 81. 1488, 1935 ; Journ. Phys. Chem., 4O. 307, 1936 ; H. P. Walmsley, Phil. Mag., (7), 7.
3097, 1929 ; W. R. Whitney and J. C. Blake, Journ. Amer. Chem. Soc, 26. 1339, 1904 ;
A. T. Williams, Nature, 180. 963, 1932 ; Compt. Mend., 201. 665, 1935 ; L. Wohler, Verh. deut.
Naturf. Aerzte, ii, 105, 1907 ; L. Wohler and A. S pen gel, KoIl. Ze^t., 7. 245, 1910 ; R. Zsigmondy,
Zur Erkenntnis der Kolloide, Jena, 146, 1905.
§ 9. The Structure of Platinum
R. J. Haiiy x first suggested that the crystals belong to the cubic system. He
said : la forme de petits cristaux de platine m'a paru Stre celle du cube ; A. Breithaupt
confirmed this with crystals of platinum from Russia ; and F. Mohs said that the
crystals are hexahedral. G. B. Sowerby found native platinum with a laminated
structure. Platinum usually occurs in grains or scales, occasionally in lumps or
nuggets -weighing up to 21 lbs.—vide supra. The structure of these grains was
discussed by R. Beck, H. O. H. Carpenter and S. Tamura, B. von Cotta, A. Daubree,
M. Ginsburg, E. Hussak, A. Inostranzeff, B. O. Karpoff, A. Liversidge, S. Meunier,
J. Orcel, V. Poschl, J. W. Retgers, F. Rinne, S. F. Schemtschuschny, and
G. H. Stanley and P. A. Wagner. Well-formed crystals are comparatively rare.
Cubes or distorted cubes are the most common crystalline forms. P. V. Jeremejeff
described some crystals which he said were usually hexahedral, rarely octahedral.
No cleavage was observed, but there is some twinning about the (lll)-plane.
Octahedral forms were also observed by E. Hussak, G. B. Sowerby, and F. Limmer.
J. Orcel obtained octahedral and tetrahedral crystals by volatilization. The colour
and streak of platinum are whitish steel-grey. F. Mylius and R. Dietz noted that
the fracture of platinum is crystalline ; native platinum has a hackly fracture.
A. Jedele studied the corrosion figures. R. Gans and R. Calatroni discussed the
nature of the ultra-microscopic particles of platinum. M. Berek discussed the microdetection
of platinum in ores.
J. J.Ebelmen obtained, by chance, during the fusion of some silicates, octahedral,
and cubo-octahedral crystals of platinum ; and J. JoIy obtained small octahedral
or cubo-octahedral crystals by heating platinum in contact with quartz, or topaz.
G. T. Beilby observed that the polished metal has a transparent, glass-like skin
which may pass into minute scales or granules. A. Guntz and H. Bassett observed
that in high temp, electric furnaces, where platinum is near its m.p., the metal
may be sublimed to form small crystals 00085 to 0-014 mm. in size. These crystals
may be cubic or octahedral, or a combination of these forms, or a combination of
cubic and tetrahedral forms. G. T. Beilby, and H. Zahn and J. Kramer noted
that amorphous layers are converted into the crystalline metal at a definite temp.
G. D. Preston studied the twinning of the crystals. G. A. Hulett and H. W. Berger,
and H. Moissan observed that small crystals are formed as a dusty sublimate when
platinum is heated in the electric furnace ; G. P. Thomson and co-workers, the
crystalline structure of thin films ; and W. Crookes, that platinum sublimed at
1300° furnishes hexagonal plates with a metallic lustre. F. W. Constant observed
mosaic crystals.
W. Campbell found that by suitably cooling platinum, a dendritic structure
could be developed in the metal. Dendrites, represented by the so-called platinum
tree, were obtained by G. F. Wach by the action of zinc on a dil. soln. of platinic
chloride ; and W. Holtz wrapped a zinc-rod (1 mm. thick and 1*5 mm. in width
at the bottom, and 3 mm. in width at the top) in paper, and when this was
immersed in a soln. of platinic chloride, a platinum tree with many branches was
developed. The tree had a metallic lustre and was hard enough to permit of filing.
J. W. Mallet observed that the etching with aqua regia of platinum which has
been fused showed up the crystalline structure ; and T. L.. Phipson observed that
the metal etched by aqua regia exhibits octahedral and tetrahedral forms , and