A Comprehensive Treatise on Inorganic and Theoretical Chemistry

388 INOKGANIC AND THEORETICAL, CHEMISTRY
of platinum in iodine vapour is greater than in air due, it is suggested, to the
formation of a film of platinic iodide which is responsible for the emission. According
to E. H. Archibald and W. A. Patrick, the mol. electrical conductivity in alcohol,
in mhos at 25° increases with dilution and attains a constant value at dilutions of
about 6(X) litres. The conductivity increases rapidly with time as indicated in
Fig. 92, but constancy is attained in about 25 hrs. at 25°. The increase is attributed
yUU
f/
175
5=> 150
X
125
100
75
\l eg- 50
2b
-5*
i
r^np^
—
—
~ition
o^oT N-so Iution
to a reaction involving the formation of a
substance having a large conductivity in the
alcohol. With methyl alcohol soln. the conductivity
is rather greater than it is in soln.
with ethyl alcohol, but similar variations with
time and concentration occur. J. L. Lassaigne
observed that platinic iodide is insoluble in
water, and is not decomposed by boiling with
water. Chlorine-water forms hydrochloroplatinic
acid, and may be chlorine iodide.
Platinic iodide combines with other iodides
to form crystalline iodoplatinates ; H. Topsoe
found that the salt is soluble in soln. of alkali
iodides, but not so readily in soln. of other
iodides. W. Manchot and Gr. Lehmann ob-
0 4 Time in hours served that in carbon monoxide, the halogen
Ki«. 92.- The Kloctrical Conductivity is displaced at a lower temp, than it is in an
of Solutions of Platinic Iodide in indifferent gas, and no carbonyl iodide is
Ethyl Alcohol. formed. According to F. Field, the rose colour
of a soln. of platinic and potassium iodides is
destroyed by soln. of urine, albumin, tannic acid, gallic acid, pyrogallic acid, potassium
cyanide or thiocyanate, the liquid in which animal or vegetable substances have
been boiled, and saliva; but not by urea, uric acid, starch, dextrin, cane-sugar, grapesugar,
glycerol, gelatin, oxalic acid, tartaric acid, citric acid, acetic acid, carbon
disulphidc, and alcohol. H. Topsoe noted that sulphurous acid converts the iodide
into platinous sulphite. J. L. Lassaigne found that cold, cone, sulphuric acid does
not act on the iodide, but when heated, iodine is evolved. R. J. Kane observed
that ammonia converts the salt into the oxyiodide, PtOI2.2NH3.H2O, and H. Topsoe
showed that an ammine is formed when platinic iodide is dissolved in aq. ammonia.
I. .Bellucci found that platinic iodide forms a green soln. with alcohol, and some of
the iodide is decomposed ; the salt dissolves in 95 per cent, alcohol without decomposition
at ordinary temp., but in light the salt is slowly decomposed. A. Schleicher
and W. Schmitz prepared platinous bisethylenediaminoiodide, [Pt ^n2]I2, and
found that dil. sulphuric acid converts it into [(H2O)—Pt(en)2—(HoO)5J(H2O)5
—Pt(en)2 —(H20)JI.5H20.
P. T. Cleve prepared platinic diiodotetramminoiodide, [Pt(NHg)4I2]I2, by the
action of an excess of potassium iodide on the corresponding dichloro-nitrate ; by
the action of iodine on platinous tetramminoiodide ; and by the action of potassium
triiodide on platinous tetramminochloride. The black scales recall graphite, the
salt also occurs in dark brown, translucent plates. The salt decomposes at 130° to
140°. A. R. Klien studied the action of water, acids, and alkaline soln. According
to P. T. Cleve, the salt is soluble in water, particularly boiling water ; mercury
reduces it to platinous tetramminoiodide ; silver nitrate slowly precipitates all the
iodine from the aq. soln. and a boiling soln. of an ammonium salt partially converts it
into platinic diiodohexammino-ju-diamineiodide, [I(NH3)3Pt(NH2)2Pt(NH3)3IJI4.
The diiodotetramminoiodide also forms lemon-yellow needles of platinic diiodotetramminoiodomercurate,
[Pt(NH3)4I2](HgI8)2. P. T. Cleve prepared platinic transtetraiododiammine,
[Pt(NH3)2I4], by the action of tincture of iodine on platinous
diiododiammine. The black, amorphous powder passes into the diiodohexamminoft-diamineiodide
when it is boiled with aq. ammonia ; boiling, cone, potash lye