Argon
2 of the 7 encyclopedias on this shelf carry an entry for Argon. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
ar'gon, an element in the air discovered in 1894 by Professors Strutt (Lord Rayleigh) and Ramsay of England. A hundred years earlier Cavendish suggested the existence of such a gas. The discoverers of argon were led to the new element-by noticing that nitrogen obtained from air was always heavier by one-half of one per cent than that prepared from compounds. Investigation proved that atmospheric nitrogen had mixed with it an element new to science. On further investigation of argon obtained from liquid air , it has been found that argon is associated with minute quantities of yet other unsuspected elements. Under ordinary conditions, argon is an odorless, tasteless, colorless gas. Argon liquefies under a pressure of 40 atmospheres at a temperature of -184 degree F., and freezes at -310 degree F. As a liquid it is denser than water. Little is known of argon's chemical properties save that it is inert and does not combine with any other element. The name is Greek and signifies inactive. See Air 2026 Editor's Note: Argon was the first of the ' noble gases ' found — its discovery forced chemists to add a whole new column to the periodic table, soon filled by neon, helium and the rest. Inert and abundant (nearly one percent of the air), it now fills incandescent bulbs and double-glazed windows and shields metal during welding. (Ed: BR 2026-07-16)
Collier's New Encyclopedia (1921)
a constituent gaseous element discovered in our atmosphere by Lord Rayleigh and Prof. Ramsay, in 1894. Argon has a characteristic spectrum. Its specific gravity (H=l) is between 19 and 21. It is about 2½ times as soluble in water as nitrogen. Its critical temperature (-121°C.) and boiling point (-187°C.) are lower than those of oxygen. It seems to be incapable of combining with anything. It has been found in cleveite and in a meteorite. There is still much doubt concerning its true status. It is separated by acting on air with red-hot copper filings to separate the oxygen. The residual gas is dried and passed over white-hot magnesium filings. The magnesium combines with the nitrogen, producing a solid nitride and leaving argon as a gas.