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CRUCIBLES |
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Platinum
is a noble metal, most abundantly and widely used in form
of Laboratory ware like Crucibles and Dishes. It is soft,
ductile, white metal which is almost inert in normal atmosphere
and resists oxidation at a high tempreture remaining bright
at all temperatures upto its high melting point of 1769 oC.
It resists the action of almost all single acids, alkalies,
solutions of simple salts and organic materials. Platinum
can be heated in oxidising condition without change of weight.
These excellent properties make platinum indespensible metal
to be used for fabrication of laboratory apparatus like crucibles,
dishes and other accessories for accurate chemical analysis.
It
is possible to make these apparatus in Platinum/Rhodium or
Platinum/Iridium alloys, we can fabricate special shapes and
sizes of crucibles, dishes or any other type of vessel to
customer's requirements.

Due
to its extremely inert characterstics, platinum rarely undergoes
chemical attack. However, there are exceptional circumstances
which would damage laboratory apparatus made of platinum and
reduce its otherwise long life. Simple precautions and systamic
handling of the apparatus can lead to substantial saving on
the long run.
Aqua
regia, hydrochloric acid plus oxidising agents will attack
platinum, as will free halogens to some degree at elevated
temperatures. A few low melting metals including lead, tin,
antimony, zinc and arsenic will readily alloy with and attack
platinum at their melting temperatures. Low melting point
phases are formed with silicon, pohsphorus, bismuth and boron
salts or compounds of these metals which could be detrimental
at high temperatures under reducing conditions. Fuse alkali
oxides, hydroxides and peroxides attack platinum readily,
so also does fused cyanides and their use should be avoided.
Cleaning
of platinum vessels is best achieved by treating them in fused
potassium bisulphate followed by boiling water. Boiling in
dilute hydrochloric acid also sometimes serve the purpose.
The dullness of surface of platinum vessels during use in
no way harmful for the apparatus and polishing should be avoided
since this would only mean loss of precious metal.
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