Hydrogen (), is the chemical element represented by the symbol H and an atomic number of 1. At standard temperature and pressure it is a colourless, odorless, nonmetal lic, tasteless, highly flammable diatomic gas (H2).
With an atomic mass of 1.00794 amu, hydrogen is th more
Speed of light :"Lightspeed" redirects here. For other uses, see Lightspeed (disambiguation) .
:For other uses of "speed of light", see speed of light (disambiguation)
The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celerit more
Cochineal is the name of both crimson or carmine dye and the cochineal insect (Dactylopius coccus), a scale insect in the suborder Sternorrhyncha , from which the dye is derived. There are other species in the genus Dactylopius which can be used to produce cochineal extract, but t more
Verbascum thapsus (; Great Mullein or Common Mullein) is a species of mullein native to Europe , northern Africa and Asia , and introduced in the Americas and Australia .
It is a hairy biennial plant that can grow to 2 m or more tall. Its small yellow flowers are dens more
Slate industry in Wales
, Wales, about 1910.
The slate industry in Wales began during the Roman period when slate was used to roof the fort at Segontium , now Caernarfon . The slate industry grew slowly until the early 18th century, then expanded rapidly until the late 19th century, at which t more