A System of Instruction in the Practical Use of the Blowpipe: Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic CombinationsAnonymous
Science
A System of Instruction in the Practical Use of the Blowpipe: Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations
Anonymous
Blowpipe
Borax dissolves a considerable quantity of cadmium oxide upon a
platinum wire to a clear yellow bead, which, when cold, is almost
colorless. If the bead is nearly saturated with the cadmium oxide, it
appears milk-white when intermittingly heated. If the bead is
completely saturated, it retains its opalescent appearance. Upon
charcoal, and in the flame of reduction, the bead intumesces, the
cadmium oxide becomes reduced to metal; this becomes volatilized and
re-oxidized, and sublimes upon the charcoal as the yellow cadmium
oxide.
In the oxidation flame, microcosmic salt dissolves a large quantity of
it to a clear bead, which, when highly saturated and while hot, is
yellowish colored, but colorless when cold. By complete saturation,
the bead is enamel-white when cold.
Upon charcoal, in the flame of reduction, the bead is slowly and only
partially reduced, a scanty sublimate being produced on the charcoal.
The addition of tin promotes the reduction.
Carbonate of soda does not dissolve cadmium oxide in the oxidation
flame. In the reduction flame, upon charcoal, it is reduced to metal,
and is volatilized to a red-brown or dark, red sublimate of cadmium
oxide upon the charcoal, at a little distance from the assay the
charcoal presenting the characteristic iridescent appearance. This
reaction is still more sensitive if the cadmium oxide is heated _per
se_ in the reduction flame.
_Antimony_ (Sb).--This metal is found in almost every country. It
principally occurs as the tersulphide (SbS^{3}), either pure or
combined with other sulphides, particularly with basic sulphides.
Sometimes it occurs as the pure metal, and rarer in a state of
oxidation as an antimonious acid and as the oxysulphide.
In the pure state, antimony has a silver-white color, with much
lustre, and presents a crystalline structure. The commercial and
impure metal is of a tin-white color, and may frequently be split in
parallel strata. It is brittle and easily pulverized. It melts at a
low red heat (810°), is volatilized at a white heat, and can be
distilled. At common temperatures it is not affected by the air. At a
glowing heat it takes fire, and burns with a white flame, and with
white fumes, forming volatile antimonious acid. Common acids oxidize
antimony, but dissolve it slightly. It is soluble in aqua regia
(nitro-hydrochloric acid).
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