Trivial name for example, hydrogen ("water-producing"), oxygen ("acid-producing"), nitrogen ("soda-producing"), bromine ("stink"), and argon ("no reaction") were based on Greek roots, while the names of iodine and chlorine were derived from the Greek words for their characteristic colors. Indium, rubidium, and thallium were similarly named for the colors of particular lines in their emission spectra. Iridium, which forms compounds of many different colors, takes its name from "iris", the Latin for "rainbow". The noble gases have all been named for their origin or properties. Helium comes from the Greek "helios", meaning "sun" because it was first detected as a line in the
Green Cross (chemical warfare) Green Cross (chemical warfare) Green Cross (Grünkreuz) is a World War I chemical warfare pulmonary agent consisting of chloropicrin (PS, Aquinite, Klop), phosgene (CG, Collongite) and/or trichloromethyl chloroformate (Surpalite, Perstoff). Green Cross is also a generic World War I German marking for artillery shells with pulmonary agents (chemical payload affecting the lungs). The tip of the projectile with the fuse end painted green and a green cross at the bottom of the cartridge. Other Green Cross mixtures were based on phosgene and/or diphosgene. The first use of Green Cross was on May 31 1915 in a German offensive in Ypres.