- Frederick the Great Playing the Flute at Sanssouci (Wikipedia)
Frederick the Great Playing the Flute at Sanssouci or The Flute Concert is an 1852 oil on canvas history painting by the German painter Adolph Menzel. It depicts Frederick the Great, King of Prussia playing the flute at an evening concert at Sanssouci and is now in the Alte Nationalgalerie in Berlin.
- Silicon dioxide (Wikipedia)
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored.