The evaporation is carried to
dryness; and the residue heated nearly to redness. The residue, which
consists of magnesia with carbonates and chlorides of the alkalies, is
extracted with water; and filtered. The filtrate is evaporated with
hydrochloric acid in a weighed platinum dish, ignited gently, and
weighed. This gives the weight of the mixed chlorides of sodium and
potassium; which are then separated and determined as described under
_Potash_.
It must be remembered when calculating the percentage that (with the
exception of the silica, tungstic acid, and tin) the determinations have
been made on 1 gram of the sample.
The following analysis will illustrate the composition of such a slag:--
Tungstic acid 1.3%
Silica 39.4
Stannous oxide 8.1
Ferrous oxide 26.2
Alumina 14.8
Oxide of manganese traces
Lime 7.9
Magnesia 0.5
Alkalies calculated as soda 1.7
-----
99.9
TITANIUM.
Titanium only occurs as a mineral in its oxidised state, or as titanic
oxide (TiO_{2}). It is a substance which has little commercial value,
and is generally recognised as one of the rare bodies; although, in
small quantities, it is widely disseminated.
Pages:
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549