- Gettysburg Address (Wikipedia)
The Gettysburg Address is a speech that U.S. President Abraham Lincoln delivered during the American Civil War at the dedication of the Soldiers’ National Cemetery, now known as Gettysburg National Cemetery, in Gettysburg, Pennsylvania on the afternoon of November 19, 1863, four and a half months after the Union armies defeated Confederate forces in the Battle of Gettysburg, the Civil War’s deadliest battle. It remains one of the best known speeches in American history.
- 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.