Any one desirous Of mastering the practical determination Of any metal in its ores and in the commercial products whose value it in?uences, perhaps could do no better, if immediate results were Of no consequence, than to choose a gravi metric and a volumetric process which worked well with pure solutions Of the metal's salts, and then to set about Observing the in?uence exerted by variations in the mode Of operating and by the presence Of other metallic salts. Such a.