Aluminium fluoride, AlF 3, obtained by dissolving the metal in hydrofluoric acid, and subliming the residue in a current of hydrogen, forms transparent, very obtuse rhombohedra, which are insoluble in water.
A religious epic, DieGeheimnisse, and a tragedy Elpenor, did not, it is true, advance much further than plans; but in 1777, under the influence of the theatrical experiments at the Weimar court, Goethe conceived and in great measure wrote a novel of the theatre, which was to have borne the title Wilhelm Meisters theatralische Sendung; and in 1779 himself took part in a representation before the court at Ettersburg, of his drama I phigenie auf Tauris.
If a i, a 2 represent the densities of the two infinite solids, their mutual attraction at distance z is per unit of area 21ra l a fZ '(z)dz, (30) or 27ra l 02 0(z), if we write f 4,(z)dz=0(z) (31) The work required to produce the separation in question is thus 2 7ru l a o 0 (z)dz; (32) and for the tension of a liquid of density a we have T = a f o 0 (z)dz.
Strauss resumed his literary activity by the publication of Der Romantiker auf dem Thron der Ciisaren, in which he drew a satirical parallel between Julian the Apostate and Frederick William IV.
Die deutsche Philologie im Grundriss (1836) was at the time of its publication a valuable contribution to philological research, and historians of German literature still attach importance to his Geschichte des deutschen Kirchenliedes bis auf Luther (1832; 3rd ed., 1861), Unsere volkstiimlichen Lieder (3rd ed., 1869) and Die deutschen Gesellschaftslieder des 16.
