The reasons were not understood until the researches of Wailer demonstrated the difference between the effects of merely dead loads and of live loads, and between repetitions of stress of one kind only, and the vastly more destructive effects of both kinds alternating.
Matters being thus settled with Rome, Pippin again took up his wars against the Saxons, against the Arabs (whom he drove from Narbonne in 758), and above all against Wailer, duke of Aquitaine, and his ally, duke Tassilo of Bavaria.
In 1855, ignorant of what Wailer had done ten years previously, he succeeded in obtaining metallic aluminium, and ultimately he devised a method by which the metal could be prepared on a large scale by the aid of sodium, the manufacture of which he also developed.
The mother liquor includes generally more or less of nickel, cobalt, zinc and other heavy metals, which, as Wailer showed, can be removed as insoluble sulphides by the addition of ammonium sulphide; uranium, under the circumstances, is not precipitated by this reagent.
In 1832 he founded the Annalen der Pharmazie, which became the Annalen der Chemie and Pharmazie in 1840 when Wailer became joint-editor with himself, and in 1837 with W6hler and Poggendorff he established the Handworterbuch der reinen and angewandten Chemie.