Barium is a chemical element with the symbol Ba and atomic number 56. It is a soft, silvery alkaline earth metal; because of its high chemical reactivity, barium is never found in nature as a free element. Its hydroxide, known in pre-modern times as baryta, does not occur as a mineral, but can be prepared by heating barium carbonate; the most common occurring minerals of barium are barite and witherite, both insoluble in water. The name barium originates from the alchemical derivative "baryta", from Greek βαρύς, meaning "heavy". Baric is the adjectival form of barium. Barium was identified as a new element in 1774, but not reduced to a metal until 1808 with the advent of electrolysis. Barium has few industrial applications, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO and electroceramics, is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds are added to fireworks to impart a green color.

Barium sulfate is used as an insoluble additive to oil well drilling fluid, as well as in a purer form, as X-ray radiocontrast agents for imaging the human gastrointestinal tract. The soluble barium ion and soluble compounds are poisonous, have been used as rodenticides. Barium is a silvery-white metal, with a slight golden shade when ultrapure; the silvery-white color of barium metal vanishes upon oxidation in air yielding a dark gray oxide layer. Barium has good electrical conductivity. Ultrapure barium is difficult to prepare, therefore many properties of barium have not been measured yet. At room temperature and pressure, barium has a body-centered cubic structure, with a barium–barium distance of 503 picometers, expanding with heating at a rate of 1.8×10−5/°C. It is a soft metal with a Mohs hardness of 1.25. Its melting temperature of 1,000 K is intermediate between those of the lighter strontium and heavier radium; the density is again intermediate between those of radium. Barium is chemically similar to magnesium and strontium, but more reactive.

It always exhibits the oxidation state of +2. Most exceptions are in a few rare and unstable molecular species that are only characterised in the gas phase such as BaF, but a barium species has been reported in a graphite intercalation compound. Reactions with chalcogens are exothermic. Reactions with other nonmetals, such as carbon, phosphorus and hydrogen, are exothermic and proceed upon heating. Reactions with water and alcohols are exothermic and release hydrogen gas: Ba + 2 ROH → Ba2 + H2↑ Barium reacts with ammonia to form complexes such as Ba6; the metal is attacked by most acids. Sulfuric acid is a notable exception because passivation stops the reaction by forming the insoluble barium sulfate on the surface. Barium combines with several metals, including aluminium, zinc and tin, forming intermetallic phases and alloys. Barium salts are white when solid and colorless when dissolved, barium ions provide no specific coloring, they are denser than the calcium analogs, except for the halides.

Barium hydroxide was known to alchemists. Unlike calcium hydroxide, it absorbs little CO2 in aqueous solutions and is therefore insensitive to atmospheric fluctuations; this property is used in calibrating pH equipment. Volatile barium compounds burn with a green to pale green flame, an efficient test to detect a barium compound; the color results from spectral lines at 455.4, 493.4, 553.6, 611.1 nm. Organobarium compounds are a growing field of knowledge: discovered are dialkylbariums and alkylhalobariums. Barium found in the Earth's crust is a mixture of seven primordial nuclides, barium-130, 132, 134 through 138. Barium-130 undergoes slow radioactive decay to xenon-130 by double beta plus decay, with a half-life of ×1021 years, its abundance is ≈ 0.1 %. Theoretically, barium-132 can undergo double beta decay to xenon-132; the radioactivity of these isotopes are so weak. Of the stable isotopes, barium-138 composes 71.7% of all barium. In total, barium has about 40 known isotopes, ranging in mass between 114 and 153.

The most stable artificial radioisotope is barium-133 with a half-life of 10.51 years. Five other isotopes have half-lives longer than a day. Barium has 10 meta states, of which barium-133m1 is the most stable with a half-life of about 39 hours. Alchemists in the early Middle Ages knew about some barium minerals. Smooth pebble-like stones of mineral baryte were found in volcanic rock near Bologna, so were called "Bologna stones". Alchemists were attracted to them; the phosphorescent properties of baryte heated with organics were described by V. Casciorolus in 16

Edward Sullivan was a Canadian Anglican priest. Sullivan was the son of a Wesleyan minister and was born in Lurgan, County Armagh, Northern Ireland in 1832, he attended grammar school at Clonmel in County Tipperary and went on to be educated at Trinity College, Dublin. He emigrated to Upper Canada in 1858 at which point he was ordered to the diaconate by Diocese of Huron Bishop Benjamin Cronyn, he was ordained as a priest in 1859. He married a family friend from Ireland. Following Hutchison's death he remarried Frances Renaud, his first appointment was a curate near, Ontario in 1859. In 1863 he was appointed to St. George's Church in Montreal. In 1868 he left Montreal to become the rector of Holy Trinity, Chicago from 1868 to 1879. Sullivan was at Holy Trinity during the Great Chicago Fire of 1871, during which the church burned to the ground. Sullivan and his congregation raised funds to rebuild Holy Trinity in mere months. In 1979 Sullivan returned of St George, Montreal as rector. Following the death of Fredrick Dawson Fauquier, the Diocese of Algoma's first bishop in 1882, Sullivan was elected in May 1882 to the Episcopate as the second Bishop of Algoma.

At age 49 he was consecrated as Bishop at St. George's Church, Montreal on June 29, 1882; when Sullivan took charge of the Algoma Diocese the diocese was still much a missionary diocese that spanned a huge physical area and was under considerable financial strain. Sullivan was responsible for the expansion of the Diocese Mission Fund and proactively seeking support from the Missionary Society of England which resulted in many churches in the diocese becoming debt free, he started a Widows' and Orphans' Fund to help financially with the dependents of deceased clergy. In 1896 this fund had reached $18,000; the fund was renamed as the Bishop Sullivan Memorial Sustentation Fund. By the 1970, the fund has reached a value of $168,000. Sullivan was responsible for the division of the Algoma Diocese into rural Deaneries, he appointed priests with regional oversight to four deaneries: Muskoka, Parry Sound and Thunder Bay. In 1895 Nipissing and Manitoulin were added as deaneries. Sullivan's health began to decline in 1893 and he began spending winters in France to recover.

He resigned as bishop in 1896 and became the rector of St James Cathedral, until his death in June 1899. Bishop Edward Sullivan fonds

Admiral Sir Edmund Percy Fenwick George Grant, was a Royal Navy officer who served as First Naval Member and Chief of the Australian Naval Staff from 1919 to 1921. Grant saw service in the Egyptian War of 1882 as well as the Brazilian Naval Mutiny in 1893, he was promoted to lieutenant on 1 October 1890, posted as a lieutenant for navigation on the battleship HMS Mars, promoted to commander on 26 June 1902. In September 1902 he was posted to HMS President for study at the Royal Naval College, he went on to serve during the First World War as flag captain to Vice Admiral Sir Lewis Bayly in HMS Marlborough and as flag captain and chief of staff to Admiral Sir Cecil Burney, second-in-command of the Grand Fleet. In that capacity he saw his ship torpedoed and crippled at the Battle of Jutland in 1916. After the war he was appointed First Naval Chief of the Australian Naval Staff. In this role, he served as defence advisor to Billy Hughes, Prime Minister of Australia at the Empire Conference in London in 1921.

He was appointed Admiral Superintendent at Portsmouth Dockyard in 1922 and retired in 1928. He was recalled during the Second World War to serve as Captain at the Port of Holyhead; the Dreadnought Project: Percy Grant