The effect of the two processes on the purity of the market lead is clearly shown by the two following analyses by Hampe, which represent lead from Lautenthal in the Harz Mountains, where the Parkes process replaced that of Pattinson, the ores and smelting process remaining practically the same: - It is absolutely necessary for the success of the Parkes process that the zinc and lead should contain only a small amount of impurity.
Hampe, Geschichte Konradins von Hohenstaufen (Berlin, 1893); del Giudice, Il Giudizio e la condanna di Corradirlb (Naples, 1876); E.
Hampe prepared chemically pure bismuth by fusing the metal with sodium carbonate and sulphur, dissolving the bismuth sulphide so formed in nitric acid, precipitating the bismuth as the basic nitrate, redissolving this salt in nitric acid, and then precipitating with ammonia.
Hampe, Geschichte Konradins von Hohenstaufen (Innsbruck, 1894).
Hampe gives 8.945 (V) for perfectly pure and compact copper.