The Students' Guide in Quantitative Analysis - Free Ebooks Library

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a Bunsen burner ;
QUANTITATIVE ANALYSIS.
add the mixed coal and sodium carbonate
little by little, replacing the cover of the crucible quickly
each time. Do not expect to effect a perfect fusion. Place
the crucible and contents in a casserole, add water, and
digest until the mass is disintegrated, and the crucible can
be removed. Add cautiously an excess of HCl, heat to
boiling, and throw down the ILSO^ with BaCl^ as usual.
If flocks of SiO, remain insoluble in HCl, evaporate to
dryness on water-bath, heat until HCl is expelled, add
water, filter, and proceed as above. If the BaSO.^ is red-
dish after ignition, wash with solution NH^CJijO, and
then with pure water, dry, ignite, and weigh again. The
BaSO^ may also be purified by solution in cone. H.SO^ and
rcprccipitation with water.
Second Method for Determining SiUphur. — VviX two to
five grms. powdered coal in a flask holding a litre; add
]00 c.c. HNO, and five grms. powdered KCIO^, heat to
boiling, adding more reagents as needed; continue until all
the carbon is oxidised. Transfer to a dish, evaporate to
dryness, add HCl and water, throw down li^SO^ with
BaCl,, and proceed as usual. Con.-^ult Hayes's article in
Am. Chem., Feb., 1875, also Wittstein's article in Am.
Ckem., April, 1S76.
P- — Calculations.
Theoretically we should deduct half S from the volatile
combustible matter (because iron pyrites loses one-half its
sulphur at a red heat), one-eighth S from the fixed car-
bon and three-eighths from the ash. (2FeS become Fe^O^,
or 8 X 4 = 32 reduces to 8 X 3 = 24.)
Tractically half the amount of sulphur is deducted from
the volatile combustible, and half from the fixed carbon;
reports should be made out accordingly