~--Titrating a solution (with 20 c.c. of
hydrochloric acid) measuring 50 c.c., and kept boiling, the quantity of
stannous chloride solution required is practically proportional to the
iron present.
Ferric chloride
added 1 c.c. 10 c.c. 20 c.c. 50 c.c. 100 c.c.
Stannous chloride
required 1.1 " 10.5 " 20.6 " 51.4 " 102.6 "
The student, having practised some of the above experiments, may proceed
to the assay of an iron ore.
~Determination of Iron in Brown Iron Ore.~--Weigh up 1 gram of the dried
and powdered ore, calcine in the cover of a platinum crucible, and
dissolve up in an evaporating dish[69] with 20 c.c. of strong
hydrochloric acid. When solution is complete, dilute to 50 c.c. after
replacing any acid that may have been evaporated. Boil, and run in the
stannous chloride solution until the colour is faintly yellow; boil
again, and continue the addition of the stannous chloride solution,
stirring continuously until the solution appears colourless. Note the
quantity of the stannous chloride solution required. Suppose this to be
59 c.c. Take 60 c.c. of the standard ferric chloride solution, add 20
c.c. of hydrochloric acid, boil and titrate in the same way as before.
Suppose this to require 61 c.c. Then as 61 is equivalent to 60 of the
iron solution, 59 is equivalent to 58.
Pages:
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466