A Comprehensive Treatise on Inorganic and Theoretical Chemistry

328 INORGANIC AND THEORETICAL, CHEMISTRY
The (0Ol)-cleavage is perfect; the sp. gr. is 2-868, and the mol. vol. is 216-0.
W. Kwasnik obtained the octohydrate, BaPtCl6.8H20, by the action of hydrochloroplatinic
acid on barium oxide, concentrating the filtered soln. on a waterbath,
precipitating with absolute alcohol, washing the product, and recrystalhzmg
from aq. soln. The hexahydrate forms the monohydrate at 70°, and the anhydrous
salt is formed at 100° in a current of dry air. W. Peters said that all the water is
lost at 150° to 160°. When heated to a higher temp., platinum and barium chloride
are formed. According to G. Gire, the vap. press., p, in ram. of mercury, is :
428° 458° 514° 556° 607° 655° 721°
p . . . 4 - 6 9-8 31-2 80-3 21O 531 16OO
The heat of formation is 40-9 CaIs. H. Precht, and H. Topsoe observed that the
salt is partially decomposed in aq. soln., and H. Precht, and P. Rohland, that the
salt is almost completely decomposed by methyl alcohol, and by ethyl alcohol.
W. Peters observed that the anhydrous salt takes up dry ammonia to form barium
hexamminochloroplatinate, BaPtCl6.6NH3, which, in vacuo, forms barium
pentamminochloroplatinate, BaPtCl6.5NH3.
J. Thomsen 2 ? prepared beryllium chloroplatinate, BePtCl6.8H2O, by dissolving
beryllium hydroxide, freed from adsorbed ammonium salts by digestion with
bromine water, in hydrochloroplatinic acid, and evaporating the soln. for crystallization.
A. Wclkow evaporated a mixture of cone. soln. of beryllium and platinic
chlorides slowly over cone, sulphuric acid. The crystals are dark yellow, being fouror
six-sided prisms, or six- or eight-sided plates. According to J. C. G. de Marignac,
the crystals belong to the tetragonal system ; and they were examined by K. Haushofer.
A. WeIkow, and J. Thomsen said that the crystals of the octohydrate are
stable in dry air, but deliquesce in moist air ; they lose 4 mols. of water at 100°
to 120°, and above 150° water and hydrogen chloride are given off. The salt is
freely soluble in water, and alcohol, but insoluble in ether.
H. Topsoe,2« and A. von Mussin-Puschkin prepared magnesium chloroplatinate,
MgPtCl6.12H2O, by evaporating a soln. of the component salts, at a low temp.
H. Topsoe, and H. Topsoe and C. Christiansen observed that the dark reddishyellow
crystals of the dodecahydrate are trigonal with the axial ratio a : c=l : 0-7057,
and a—106 0 39' ; the crystals arc birefringent. The sp. gr. is 2-060, and the mol.
vol. 315-3. The crystals are stable in air, but pass into the hexahydrate at 100°.
JJ. Pauling studied the crystals. P. A. von Bonsdorff obtained the hexahydrate
by the spontaneous evaporation of an aq. soln. of the component salts, .and
H. Topsoe added, at a temp, higher than that needed for the dodecahydrate ; it
is also obtained by slowly cooling a sat. soln. down to about 20°. H. Precht found
that the salt cannot be purified by recrystallization. H. Topsoe observed that the
pale yellow crystals arc trigonal, with the axial ratio a : c==l : 0-5169, and
ct-=ll2° 10' ; the sp. gr. is 2-437, and the mol. vol. 222-5. P. Gaubert found the
refractive indices vary with the moisture content ; and for the heptahydrate, for
sodium light, OJ = 1-561, and e=-l-91. P. A. von Bonsdorff said that the crystals
are stable in air, but H: Topsoe found that the crystals rapidly absorb moisture
to form a pale yellow powder. According to P. A. von Bonsdorff, the crystals lose
4 mols. of water when heated. H. Precht found that the hexahydrate dissolves
in absolute alcohol forming a sat. soln. with 43-2 per cent, of MgPtCl6, but with
the salt dried at 150°, the soln. contains only 37-8 per cent. P. Rohland added
that the salt is soluble in 8O per cent, alcohol of sp. gr. 0-8055 at 15° ; and in
methyl alcohol of sp. gr. 0-790 at 17°, but it is insoluble in ether. The alcoholic
soln. suffers some dissociation, forming magnesium chloride.
IJ. Htinefeld prepared zinc chloroplatinate, ZnPtCl6.6H2O, by treating a soln.
of platinum in aqua regia with zinc until the soln. acquires a pale yellow colour,
and evaporating the filtrate ; the first crop of crystals is the chloroplatinite, and
the later crop, chloroplatinate. A. Eberhard said that the crystals are red.
P. A. von Bonsdorff obtained the salt by crystallization from a mixed soln. of the