A Comprehensive Treatise on Inorganic and Theoretical Chemistry

218 INORGANIC AND THEORETICAL, CHEMISTRY
The results are summarized in Fig. 57. In the quenched samples two solid, soln.
are indicated with 0 to 40 at. per cent, of platinum, and 35 to 1OO at. per cent,
with the annealed samples, the first maximum corresponds with the formation of
a platinum ferride, PtFe. G. H. Billings said that platinum makes iron harder,
but less so than does the same proportion of carbon. E. Jiinecke observed that the
lowest m.p., 1500°, occurs with alloys having 7 at. per cent, of platinum. W. Wien
0 20 40 GO 80 Job ° 20 40 60 80 70 °
Atom per cent. Pt Atom per cent. Pt
Fro. 57. The Hardness of the Iron- Fia. 58. The Temperature Coefficient of the
Platinum Alloys. Electrical !Resistance of the Fe-Pt Alloys.
studied the optical properties of an alloy of iron and platinum. C. Barus measured
the electrical resistance and its temp, coeff. L. AV. Haase studied the
oxygen depolarization current ; and J. Wiirschmidt, the thermoelectric force.
H. St. C. Devillc and H. Debray said that alloys with 17 and 20 per cent, of iron
are magnetic. A. Daubree found that an alloy with 16-87 per cent, of iron
exhibits magnetic polarity, but an alloy with 11 per cent, of iron is only feebly
magnetic. F. Aallot studied the Curie point, and the magnetic moment.
W. Jellinghaus studied the coercive force.
C. F. Schonbein observed that an alloy with 1 per cent, of platinum is not
attacked by nitric acid, and this was confirmed by JP. Monnartz. The alloys are
soluble in aqua regia. According to J. B. J. D. Boussingault, if the pyrophoric
alloy, just mentioned, be placed in hydrochloric acid, without coming in contact
with air, part of the iron dissolves with, the evolution of hydrogen. The heavy,
black powder which remains as a residue after washing contains about 20 per cent,
of iron which may be dissolved out with nitric acid, and it also contains a trace of
moisture but no hydrogen. The residue takes fire in air below a red-heat, and
burns with the emission of sparks. Sometimes the combustion begins at the
hottest part, and spreads throughout the mass with a red light, as in the burning
of tinder. The powder, after combustion, gains 1 per cent, in weight.
J. Murray did not obtain alloys of platinum and steel at the temp, of an alcohol
flame. W. Lewis said that platinum forms with cast iron a dark, malleable, very
hard alloy ; G. H. Billings prepared an alloy with 4 per cent, platinum with cast
iron containing 2 per cent, of carbon, and found that it could be hammered and
rolled though showing signs of red-shortness. J. Stodart and M. Faraday described
the following platinum-steel alloys : 9 : 2-alloy : perfect alloy, sp. gr. 15-88, does
not tarnish in air ; 1 : 1-alloy : crystalline structure, sp. gr. 9-862, takes high
polish, does not tarnish in air ; 1 : 8-alloy : finely damasced alloy ; 1 : 10-alloy :
sp. gr. 8-1 ; 1 : 67-alloy : best adapted for cutting instruments ; and 1 : 100-alloy :
uniform surface, fine fracture, not so hard as silver-steel, but is much tougher.
J. R. Breant, and H. Bush found that the 1 : 200 alloy can be damasced very well
and is adapted for razors. H. Remy and H. Gonnington studied the catalytic effect
in the hydrogen-oxygen reaction. J. Stodart and M. Faraday found that steel