c. per hour, and collected in a beaker.
The burner is placed in a glass bell-shaped combustion chamber connected
at the top through a right-angled tube with the condenser, and closed
below by a metal base through which the burner is passed. The amount of
gas burnt for one determination is from 50 to 100 litres. When the gas is
extinguished, the volume consumed is noted, and after cooling, the
combustion chamber and condenser are washed out with the liquid collected
in the beaker and finally with distilled water, and the whole, amounting
to about 400 c.c., is neutralised with solution of caustic alkali (if
decinormal alkali is used, the total acidity of the liquid thus
ascertained may be taken as a convenient expression of the aggregate
amount of the sulphuric, phosphoric and silicic acids resulting from the
combustion of the total corresponding impurities in the gas), acidified
with hydrochloric acid, and evaporated to dryness with the addition
towards the end of a few drops of nitric acid. The residue is taken up in
dilute hydrochloric acid; and silica filtered off and estimated if
desired. To the filtrate, ammonia and magnesia mixture are added, and the
magnesium pyrophosphate separated and weighed with the usual precautions.
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