Earth barium

In 1783 he published an annotated translation of Torbem Bergman s Sciagraphia regni mineralis, and in the following year he communicated to the Philosophical Transactions his Experiments and observations on terra ponderosa (barium carbonate, or witherite) (96). He stated that the specimen he examined came from a lead mine at Alston Moor, on the Pennines of Cumberland. Although he at first mistook it for heavy spar (barite) he soon found it to be a compound of heavy earth (barium oxide) and fixed air (carbon dioxide) (97). 

The agreement between these two tests indicated no significant change in leach rate with time on this short time scale, for the particular elements studied ( i.e.j barium, strontium, cerium, and rare earths). It was not possible to determine the cesium content in these granules because, for economy reasons, cesium was not included in the calcine production. The results of these measurements are given in Table III. Significant differences in the leach rates of the alkaline earths (barium, strontium) the RE (europium), and cerium are observable. 

Strontium, element number 38, has a density of 2.63 g/cm3 and is the 16th most abundant element on Earth. Barium, element number 56, has a density of 3.51 g/cm3 and ranks 14th in abundance. Both elements are silvery-colored metals. Because alkaline earths react so readily with any water in the environment to form ions and compounds, neither element would ever be found as the native metal. In all of their ores, they occur as +2 ions. The principal sources of the two elements are the minerals celestite (SrS04), strontianite (SrC03), and barite (BaS04). 

DICHLOROETHANE or 1,1-DICHLOROETHANE (75-34-3) C2H4CI2 Forms explosive mixture with air [explosion limits in air (vol %) 5.6 to 11.4 flash point 10°F/-12°C autoignition temp 856°F/458°C Fire Rating 3]. Violent reaction with strong oxidizers, potassium powdered metals alkaline earth (barium, calcium, strontium sometime magnesium is included) and alkali metals (lifliium, sodium. 

Catalytic reductions have been carried out under an extremely wide range of reaction conditions. Temperatures of 20 C to over 300 C have been described. Pressures from atmospheric to several thousand pounds have been used. Catal3rsts have included nickel, copper, cobalt, chromium, iron, tin, silver, platinum, palladium, rhodium, molybdenum, tungsten, titanium and many others. They have been used as free metals, in finely divided form for enhanced activity, or as compounds (such as oxides or sulfides). Catalysts have been used singly and in combination, also on carriers, such as alumina, magnesia, carbon, silica, pumice, clays, earths, barium sulfate, etc., or in unsupported form. Reactions have been carried out with organic solvents, without solvents, and in water dispersion. Finally, various additives, such as sodium acetate, sodium hydroxide, sulfuric acid, ammonia, carbon monoxide, and others, have been used for special purposes. It is obvious that conditions must be varied from case to case to obtain optimum economics, yield, and quality. 

In a few days, Davy successfully isolated sodium. His voltaic pile also gave him the alkaline earths barium, strontium, calcium, and magnesium. (Lavoisier correctly identified their oxides as compounds but could not isolate the metals.)... 

Antimony trioxide Zinc oxide Magnesium oxide Quartz Diatomaceous earth Tripoli Hydrogel Aerogel Magnesium silicate Clay Talc Mica Asbestos Feldspar Wollastonite Pumice Vermiculite Slate flour Fuller s earth Barium sulfate Graphite Copper Bronze Lead Steel Zinc ferrite Magnetite Molybdenum disulphide... 

Light-colored fillers do play an important role in NBR compounding, especially in the roller business. The main types of non-black fillers used with nitrile rubber are silica, silicate, clay, talc, and calcium carbonate. In addition there are many specialty light-colored fillers such as diatomaceous earth, barium sulfate, titanium dioxide, aluminum trioxide, antimony trioxide, magnesium hydroxide, and zinc oxide to name a few. 

The alkaline earths, barium and strontium, also show a negative temperature coefficient, but not so strongly as do the rare earths almost no ( ffect can l>e seen when the temperature of precipitating solutions is in-... 

The manufacture of rare earth barium copper oxide high-temperature superconductor ceramics is carried out by sintering at 930-1000°C in ozone atmosphere containing oxygen. Y Oj, BaC03 and CuO are mixed, calcinated, pulverized, pressed and sintered at 950°C in the presence of ozone-oxygen mixture after which they are gradually cooled to the critical superconductive temperature 94K [155]. 

It can be seen from Fig. 14 that this tetragonal oxide, bears a relation to the cubic perovskite (BaTiOj, [11]) structure-type which lies in the cubic space group Im-3m, not shown here, in which, by removal of an axial pair of oxygen vertices, one ean generate the Kentuckia structure-type from the perovskite stmcture-t5 e. However, it should be pointed out that the perovskite structure-t5 e is a 6-,12-connected network, in which the transition metal titanium and chalcogenide oxygen centers, attain octahedral 6-coordination, while the alkaline earth barium cation bears a closest packed coordination sphere of 12. Whereas in the Kentuckia structure-t5 e, the lattice, by great contrast as can be seen in Fig. 14, bears an... 

---