370; Haupt, Opusc. i.
Marggraf showed that alumina is one of the constituents of alum, but that this earth possesses peculiar properties, and is one of the ingredients in common clay (Experiences faites sur la terre de l'alun, Marggraf's Opusc. ii.
He also showed that crystals of alum cannot be obtained by dissolving alumina in sulphuric acid and evaporating the solutions, but when a solution of potash or ammonia is dropped into this liquid, it immediately deposits perfect crystals of alum (Sur la regeneration de l'alun, Marggraf's Opusc. ii.
Bergman also observed that the addition of potash or ammonia made the solution of alumina in sulphuric acid crystallize, but that the same effect was not produced by the addition of soda or of lime (De confectione aluminus, Bergman's Opusc. i.
Bergman in 1775 (De niccolo,opusc. 2, p. 231; 3, P. 459; 4, P. 374).
And Urban II., at the councils of Rome and Amalfi (1051, 1089), s Opusc. xvii.
Early in the 6th century Ennodius, bishop of Pavia, pointed out the three-fold elements of a waxcandle (Opusc. ix.
Venerandis compactam elementis facem tibi, Domine, mancipamus: in qua trium copula munerum primum de impari numero complacebit: quae quod gratis Deo veniat auctoribus, non habetur incertum: unum quod de fetibus fluminum accedunt nutrimenta flammarum: aliud quod apum tribuit intemerata fecunditas, in quarum partibus nulla partitur damna virginitas: ignis etiam coelo infusus adhibetur " (Opusc. x.