The sounds of crackling and the din of falling walls and ceilings, the whistle and hiss of the flames, the excited shouts of the people, and the sight of the swaying smoke, now gathering into thick black clouds and now soaring up with glittering sparks, with here and there dense sheaves of flame (now red and now like golden fish scales creeping along the walls), and the heat and smoke and rapidity of motion, produced on Pierre the usual animating effects of a conflagration.
It fuses easily in the electric arc. It oxidizes superficially when heated, but fairly rapidly when ignited in an oxidizing blowpipe flame, forming a black smoke of the oxide.
Its crimson flame-coloration was observed by C. G.
The methods of chemical analysis may be classified according to the type of reaction: (I) dry or blowpipe analysis, which consists in an examination of the substance in the dry condition; this includes such tests as ignition in a tube, ignition on charcoal in the blowpipe flame, fusion with borax, microcosmic salt or fluxes, and flame colorations (in quantitative work the dry methods are sometimes termed " dry assaying "); (2) wet analysis, in which a solution of the substance is treated with reagents which produce specific reactions when certain elements or groups of elements are present.
Of the principal workers in this field we may notice Friedrich Hoffmann, Andreas Sigismund Marggraf (who detected iron by its reaction with potassium ferrocyanide, and potassium and sodium by their flame colorations), and especially Carl Scheele and Torbern Olof Bergman.