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Index (R)
RA - RC
RD - RF
RG - RJ
RK - RN
RO - RR
RS - RV
RW - RZ
Moment of truth
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More than 25 million people died in Europe from the bubonic plague (the black death) in five years, from 1347 to 1352. |
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RO - RR
roasting Min. Ext.
A process in mineral extraction by heating an ore, usually a sulfide, in air to convert it to an oxide. For example, galena (lead sulfide) is heated in air to convert it to lead oxide:
which is then reduced by coke (carbon) in a blast furnace to give lead. The corrosive byproduct, sulfur dioxide (SO2), can be safely removed by allowing it to react with calcium carbonate.
rock salt Min.
Common name for the naturally occurring mineral sodium chloride. See halite.
Rose's metal Eng.
An alloy of bismuth (50%) that contains 25-28% lead snd 22-25% tin. It is a low-melting point, fusible alloy at 100°C. It is used in castings and mouldings.
RO - RR
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