impurity atmosphere
21environmental works — ▪ civil engineering Introduction infrastructure that provides cities and towns with water supply, waste disposal, and pollution control services. They include extensive networks of reservoirs, pipelines, treatment systems, pumping stations …
22Helium — otherusesHelium (He) is a colorless, odorless, tasteless, non toxic, inert monatomic chemical element that heads the noble gas group in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the… …
23Power ring (weapon) — This article is about the Green Lantern Corps weapon. For the comic book characters, see Power Ring (character). A power ring is a weapon in the DC Universe, most notably used by the Green Lantern Corps. These rings are considered to be the most… …
24Sapphire — For other uses, see Sapphire (disambiguation). Sapphire The 423 carat (85 g) blue Logan sapphire General Category Oxide mineral …
25List of Green Lanterns — The Green Lantern Corps that appear in fictional stories published by DC Comics has at least 7200 members, two per sector (originally 3600 with one per sector), in addition to assorted other members who fulfill roles other than patrolling.… …
26metallurgy — metallurgic, metallurgical, adj. metallurgically, adv. metallurgist /met l err jist/ or, esp. Brit., /meuh tal euhr jist/, n. /met l err jee/ or, esp. Brit., /meuh tal euhr jee/, n. 1. the technique or science of working or heating metals so as… …
27English literature — Introduction the body of written works produced in the English language by inhabitants of the British Isles (including Ireland) from the 7th century to the present day. The major literatures written in English outside the British Isles are… …
28Ice — This article is about water ice. For the broader concept of ices as used in the planetary sciences, see volatiles. For other uses, see Ice (disambiguation) …
29chemistry — /kem euh stree/, n., pl. chemistries. 1. the science that deals with the composition and properties of substances and various elementary forms of matter. Cf. element (def. 2). 2. chemical properties, reactions, phenomena, etc.: the chemistry of… …
30Properties of water — H2O and HOH redirect here. For other uses, see H2O (disambiguation) and HOH (disambiguation). This article is about the physical and chemical properties of pure water. For general discussion and its distribution and importance in life, see Water …
