Glass is in widespread use in optical systems due to its ability to refract, reflect, and transmit light following geometrical optics. The most common and oldest applications of glass in optics are as lenses, windows, mirrors, and prisms. [56] The key optical properties refractive index, dispersion, and transmission, of glass are strongly dependent on chemical composition and, to a lesser degree, its thermal history. [56] Optical glass typically has a refractive index of 1.4 to 2.4, and an Abbe number (which characterises dispersion) of 15 to 100. [56] Refractive index may be modified by high-density (refractive index increases) or low-density (refractive index decreases) additives. [57] Glass helped to tie ancient empires together, says Thilo Rehren, an archaeological materials scientist at the Cyprus Institute in Nicosia who has examined the craftsmanship behind objects from Tut’s tomb, among others. Kings shipped materials to other rulers, expecting goods or loyalty in return, he says. Ancient inventories from the Late Bronze Age reveal an exchange of ivory, gems, wood, animals, people and more, and while the role of glass in this convention of gifting and tribute isn’t fully understood, the composition of artifacts supports glass swaps too. It’s still not as flexible a system as Sky Q, where you can record any programme, watch it whenever you like and keep it on your hard disk in perpetuity. a b c Gibbs, Philip. "Is glass liquid or solid?". Archived from the original on 29 March 2007 . Retrieved 21 March 2007.

a b c d Elliot, S.R. (1984). Physics of Amorphous Materials. Longman group ltd. pp.1–52. ISBN 0-582-44636-8. a b Gardner, Irvine Clifton; Hahner, Clarence H. (1949). Research and Development in Applied Optics and Optical Glass at the National Bureau of Standards: A Review and Bibliography. U.S. Government Printing Office. p.13. ISBN 9780598682413. Today, glass is ordinary, on-the-kitchen-shelf stuff. But early in its history, glass was bling for kings. During the 13th century, the island of Murano, Venice, became a centre for glass making, building on medieval techniques to produce colourful ornamental pieces in large quantities. [39] Murano glass makers developed the exceptionally clear colourless glass cristallo, so called for its resemblance to natural crystal, which was extensively used for windows, mirrors, ships' lanterns, and lenses. [21] In the 13th, 14th, and 15th centuries, enamelling and gilding on glass vessels was perfected in Egypt and Syria. [44] Towards the end of the 17th century, Bohemia became an important region for glass production, remaining so until the start of the 20th century. By the 17th century, glass in the Venetian tradition was also being produced in England. In about 1675, George Ravenscroft invented lead crystal glass, with cut glass becoming fashionable in the 18th century. [39] Ornamental glass objects became an important art medium during the Art Nouveau period in the late 19th century. [39] a b c Werner Vogel: "Glass Chemistry"; Springer-Verlag Berlin and Heidelberg GmbH & Co. K; 2nd revised edition (November 1994), ISBN 3-540-57572-3The Extra-white flint glass offered by Saverglass is an exceptional glass characterized by its transparency, its unique brilliance and luster.

Rivera, V. A. G.; Manzani, Danilo (30 March 2017). Technological Advances in Tellurite Glasses: Properties, Processing, and Applications. Springer. p.214. ISBN 978-3-319-53038-3. Sodium carbonate (Na 2CO 3, "soda") is a common additive and acts to lower the glass-transition temperature. However, sodium silicate is water-soluble, so lime (CaO, calcium oxide, generally obtained from limestone), along with magnesium oxide (MgO), and aluminium oxide (Al 2O 3), are commonly added to improve chemical durability. Soda–lime glasses (Na 2O) + lime (CaO) + magnesia (MgO) + alumina (Al 2O 3) account for over 75% of manufactured glass, containing about 70 to 74% silica by weight. [68] [76] Soda–lime–silicate glass is transparent, easily formed, and most suitable for window glass and tableware. [77] However, it has a high thermal expansion and poor resistance to heat. [77] Soda–lime glass is typically used for windows, bottles, light bulbs, and jars. [75] Borosilicate A Pyrex borosilicate glass measuring cupIt’s important to note that Sky Glass does not record TV to local storage like Sky Q. Instead, users add the content they want to watch later to their “Playlist”, where it becomes accessible depending on the restrictions of the streaming/catchup service it first appeared on. I eventually managed to connect it to my home Wi-Fi using the TV’s WPS button and the same on my Devolo Magic Powerline adapter. If you come across the same issue, you’ll have to (rather counterintuitively) select the “I have Sky Broadband” option, as the “third-party broadband” connection option doesn’t give you the choice of using WPS. Richerson, David W. (1992). Modern ceramic engineering: properties, processing and use in design (2nded.). New York: Dekker. pp.577–578. ISBN 978-0-8247-8634-2. Thousands of years ago, the pharaohs of ancient Egypt surrounded themselves with the stuff, even in death, leaving stunning specimens for archaeologists to uncover. King Tutankhamen’s tomb housed a decorative writing palette and two blue-hued headrests made of solid glass that may once have supported the head of sleeping royals. His funerary mask sports blue glass inlays that alternate with gold to frame the king’s face. Whitehouse, David (2003). Roman Glass in the Corning Museum of Glass, Volume 3. Hudson Hills. p.45. ISBN 978-0-87290-155-1.