 Carl von Sickingen researched platinum extensively in 1772 . He succeeded in making malleable platinum by alloying it with gold , dissolving the alloy in hot aqua regia , precipitating the platinum with ammonium chloride , igniting the ammonium chloroplatinate , and hammering the resulting finely divided platinum to make it cohere . Franz Karl Achard made the first platinum crucible in 1784 . He worked with the platinum by fusing it with arsenic , then later <unk> the arsenic . 
