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December, 1925
Forging - Stamping - Heat Tieating
D e t e r m i n a t i o n o f C a r b o n a n d S u l p h u r
IN Forging-Stamping-Heat Treating of December
1922, I translated a method for the determination of
sulphur by combustion in oxygen. Mr. A. Vita, the
author of this method, continued his investigation to
include the simultaneous determination of carbon.
Several difficulties had to be overcome. First, it
was found that the top of the graduated burrette was
too small. It was, therefore, enlarged to approximately
100 cc, which proved to be sufficient, if the
double wash bottle, which contains the potassium
iodide—iodate solution is chosen correspondingly
smaller. Those used in the experiment contained
approximately 65 cc. The absorption pipette -also had
to be enlarged considerably.
By RICHARD RIMBACH*
S%
Sample Gravametric
Ferro-Manganese 30% .018
Ferro-Manganese 80% .018
Basic Pig Iron, 1.5% Phosphorus .06
Basic Pig Iron, 1.5% Phosphorus .16
Open Hearth Steel, Acid 046
Open Hearth Steel, Acid 036
Open Hearth Steel, Acid 037
Open Hearth Steel, Acid 058
Onen Hearth Steel. Basic 04
The tests were started with a ferro-manganese
having a carbon content of 4.60 per cent. During the
combustion, as was the case in the determination of
carbon, the leveling bottle was set up on top of the
case. The gases, therefore, entered the potassium
iodide—iodate solution, which was used undiluted (30
gms. of potassium iodide and 3 gms of potassium
iodate per liter), under pressure. The sulphur content
in most cases came out too high and the carbon
•Metallurgist, Pittsburgh, Pa.
439
content too low. If the carbon dioxide was passed
through the potassium iodide—iodate solution under
excessive pressure, part of the carbon dioxide remained
in the solution and freed iodine. For this
reason on the one hand the carbon results were too
low—in amounts up to 0.2 per cent—on the other
hand the sulphur results were too high.
This condition was avoided in that the combustion
was carried on under vacuum by placing the leveling
bottle down low and the concentration of the potassium
iodide—iodate solution was reduced to 1/3 that
given above. In the first part of the wash bottle
20 cc. of the diluted solution was placed and in the
TABLE I Simultaneous Determination
S% C% on the same Sample
Combustion Combustion S% C%
Colorimetric Volumetric Colorimetric Volumetric
.015
.015
.06
.16
.045
.03
.04
.05
.035
4.60
6.88
3.22
3.30
0.31
0.35
0.12
0.10
0.085
.018
.018
.06
.16
.05
.03
.035
.055
.035
4.56
6.84
3.30
3.29
0.30
0.34
0.13
0.095
0.085
second part 10 cc. If after the determination is made
the shade of the solution upon diluting should not
check with the comparison solution of potassium
bichromate; this condition can be remedied by the
addition of several crystals of potassium iodide.
It should be kept in mind that the combustion
boats must be put into the combustion tube at a temperature
of 1,200-1,250 deg. C, that vacuum be created
by lowering the leveling bottle, and then only
(Concluded on page 446)
FIG. 1—Apparatus used fer the simultaneous determination of carbon and sulphur.