A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM 305
redaction proceeds very slowly except in the presence of carbonate. Platinum
black prepared by reduction with an excess of sodium formate retains sodium
formate very tenaciously. If the ratio HCOONa : H2PtCl6 is less than 2:1, the
black is mixed with hydroxide and gives off oxygen when heated ; gas-free platinum
black is produced when the ratio is just 2 : l,and the product is grey,and not finelydivided.
An excess of formate is required for finely-divided metal. F. Pace prepared
a double salt with cocaine and hydrochloroplatinic acid ; and R. Fricke and
!F. Ruschhaupt, double salts with benzamide, and with acetamide.
The salts of hydrochloroplatinic acid, with PtCl6 as a bivalent radicle, are
chloroplatinates. L. F. Nilson arranged the chloroplatinates in groups typified
by : 2R 7 CLPtCl4, R"Cl2.PtCl4, R'"Cl3.PtCl4, and R""Cl4.PtCl4. F. Morges, and
P. Walden showed that they are simple salts with the PtCl6 as a bivalent radicle,
and are not double salts. The general properties were studied by P. Rohland ;
and the relation stabilities of the halogenoplatinates, by H. I. Schlesinger and
R. E. Palmateer. O. Stelling studied the electrolytic reduction of the hydrochloric
acid soln. M. Delepine and P. Boussi studied the dehydration of the
chloroplatinates, but obtained no evidence of the presence of polymerized water
molecules.
According to W. Peters, 2 when anhydrous platinic chloride is exposed to the action
of dry ammonia, it takes up 6 mols. to form platinic hexam mi no tetrachloride,
fPt(NH3)6]Cl4. This compound loses a mol. of ammonia in vacuo, but takes it
up again in an atm. of ammonia. B. Gerdes obtained this hexammine by adding
hydrochloric acid to a soln of the carbonate in dil. soda-lye. The nature of the
salt was discussed by S. H. C. Briggs, P. Klason, and J. A. N. Friend. According
to B. Gerdes, the white acicular crystals gradually pass into amber-yellow rhombohedra.
They are stable at 110°, and readily soluble in water. A. Werner and
A. Miolati found the mol. conductivities of soln. with a mol of the salt in 25O, 500,
IOOO, and 2000 litres to be, respectively, 432-5, 483-9, 522-9, and 553-5. G. Beck, and
I. I. TscherniaefT and S. I. Chorunshenkofx studied the ionization constants ; and
A. A. Griinberg and G. P. Faermann, the acidity of the salts. A. A. Griinberg, and
G. Schwarzenbach gave for the effects of acidifying the platinum hexammines :
[Pt(NH3)614 + -^[Pt(NH3)5.(NH2) 13++H^ = —0-55 volt; and [Pt(NH3J5(H2O)]^
^lPt(NH3)5(OH)P+ +II+-== -—0-23 volt. B. Gerdes observed that platinic and
auric chlorides gave sparingly soluble precipitates. That produced by the former
is the dihydrate, [Pt(NH3)6 |04.2H20, which furnishes yellow octahedra which
lose their water at 120°, and become paler in colour.
O. Carlgren and P. T. CIeve prepared platinic dihydroxytetramminochloride,
[Pt(NH3)4(OH)2]Cl2, by the action of 3 per cent, hydrogen dioxide on p latino us
tetramminochloride ; and by the action of barium chloride on the corresponding
sulphate. Li. A. Tschugaeff and W. Chlopin found that this compound is formed by
the action of hydrogen dioxide on platinous cis-dichlorodiammine. O. Carlgren
and P. T. Cleve said that the aq. soln. furnishes colourless, monociinic plates which
K. Johansson found to have the axial ratios a : b i c—1-5310 : 1 : 0-6702, and
and /?=100° 34' ; the (HO)-cleavage is incomplete. A. Werner, and A. Werner
and A. Miolati found the mol. conductivity of soln. with a mol of the salt in 125,
25O, and 5OO litres at 20° to be, respectively, 204-9, 218-8, and 225-7. O. Carlgren
and P. T. Cleve found that 100 parts of cold water dissolve 0-485 part of the salt,
and boiling water, 2*04 parts. Hydrochloric acid precipitates platinic dichlorotetramminochloride
from the soln.
The product obtained by W. Peters by keeping the hexammine in vacuo is
possibly platinic cHoropentamnunochloride, [Pt(NH3)6ClJCl3; and L.. A. Tschugaeff
and N. VladimirofE, and L.. A. Tschugaeff and W. Chlopin obtained it by the
action of ammonia and ammonium carbonate on platinous 2raws-dichlorodiammine.
A. A. Griinberg and G. P. Faermann discussed the acidity of the salt. L.. A. Tschugaeff,
and L.. A. TschugaefE and W. Chlopin also prepared platinic chloropentamminocMoroplatinate,[Pt(NH3)BClJCl.PtCl6.2H20;
platinic hydroxsrpentamminocnloride,^
VOI*. XVI. x ^ r^= 3