He was the first to discover uranium, zirconium and titanium, and to characterize them as distinct elements, though he did not obtain any of them in the pure metallic state; and he elucidated the composition of numerous substances till then imperfectly known, including compounds of the then newly recognized elements: tellurium, strontium, cerium and chromium.
The so-called alkaline earth-metals are the elements beryllium, magnesium, calcium, strontium and barium.
The metals comprising this group are never found in the uncombined condition, but occur most often in the form of carbonates and sulphates; they form oxides of the type RO, and in the case of calcium, strontium and barium, of the type R02.
Beryllium and magnesium are permanent in dry air; calcium, strontium and barium, however, oxidize rapidly on exposure.
The mineral is usually found in a state of considerable chemical purity, though small amounts of strontium and calcium sulphates may isomorphously replace the barium sulphate: ammonium sulphate is also sometimes present, whilst clay, silica, bituminous matter, &c., may be enclosed as impurities.
Crystals of barytes are orthorhombic and isomorphous with the strontium and lead sulphates (celestite and anglesite); they are usually very perfectly developed and present great variety of form.
In 1808 Davy isolated sodium and potassium; he then turned his attention to the preparation of metallic calcium, barium, strontium and magnesium.
(() An infusible white residue may be obtained,which may denote barium, strontium, calcium, magnesium, aluminium or zinc. The first three give characteristic flame colorations (see below); the last three, when moistened with cobalt nitrate and re-ignited, give coloured masses; aluminium (or silica) gives a brilliant blue; zinc gives a green; whilst magnesium phosphates or arsenate (and to a less degree the phosphates of the alkaline earths) give a violet mass.
Ammonium carbonate is added to the filtrate; this precipitates calcium, strontium and barium.
The next group may contain the white calcium, barium and strontium carbonates.
The solution free from barium is treated with ammonia and ammonium sulphate, which precipitates strontium, and the calcium in the solution may be identified by the white precipitate with ammonium oxalate.
Calcium carbonate separates as hexagonal calcite from cold solutions (below 30°), and as rhombic aragonite from solutions at higher temperatures; lead and strontium carbonates, however, induce the separation of aragonite at lower temperatures.
Many are found as minerals, the more important of such naturally occurring carbonates being cerussite (lead carbonate, PbC03), malachite and azurite (both basic copper carbonates), calamine (zinc carbonate, ZnCO 3), witherite (barium carbonate, BaCO 3), strontianite (strontium carbonate, SrC03), calcite (calcium carbonate, CaC03), dolomite (calcium magnesium carbonate, CaCO 3 MgCO 3), and sodium carbonate, Na 2 CO 3.
Practically non-volatile: (copper), iron, nickel, cobalt, aluminium; also lithium, barium, strontium and calcium.
Water, at ordinary or slightly elevated temperatures, is decomposed more or less readily, with evolution of hydrogen gas and formation of a basic hydrate, by (I) potassium (formation of KHO), sodium (NaHO), lithium (LiOH), barium, strontium, calcium (BaH 2 O 2, &c.); (2) magnesium, zinc, manganese (MgO 2 H 2, &c.).
Somewhat less volatile than the last-named group are the chlorides (MC1 2) of barium, strontium and calcium.
Barium and strontium have also been produced by electrometallurgical methods, but the processes have only a laboratory interest at present.
STRONTIUM [[[Symbol]] Sr, atomic weight 87.62 (0 = 16)], a metallic chemical element belonging to the alkaline earth group. It is found in small quantities very widely distributed in various rocks and soils, and in mineral waters; its chief sources are the minerals strontianite, celestine and barytocelestine.
With dry ammonia at 60° the metal forms strontium ammonium, which slowly decomposes in a vacuum at 20° giving Sr(NH 3) 2; with carbon monoxide it gives Sr(CO) 2; with oxygen it forms the monoxide and peroxide, and with nitric oxide it gives the hyponitrite (Roederer, Bull.
The hydride, SrH 2, was obtained by Guntz on heating strontium amalgam in a current of hydrogen.
A hydrated dioxide, approximating in composition to SrO 2.8H 2 O, is formed as a crystalline precipitate when hydrogen peroxide is added to an aqueous solution of strontium hydroxide.
Strontium chloride, SrC1 2.6H 2 O, is obtained by dissolving the carbonate in hydrochloric acid, or by fusing the carbonate with calcium chloride and extracting the melt with water.
The anhydrous chloride is formed by heating strontium or its monoxide in chlorine, or by heating the hydrated chloride in a current of hydrochloric acid gas.
Strontium sulphide, SrS, is formed when the carbonate is heated to redness in a stream of sulphuretted hydrogen.
Strontium sulphate, SrSO 4, found in the mineral kingdom as celestine, is formed when sulphuric acid or a soluble sulphate is added to a solution of a strontium salt.
When boiled with alkaline carbonates it is converted into strontium carbonate.
Strontium nitride, Sr 3 N 2, is formed when strontium amalgam is heated to redness in a stream of nitrogen or by igniting the oxide with magnesium (H.
Strontium nitrate, Sr(N03)2, is obtained by dissolving the carbonate in dilute nitric acid.
A strontium boride, SrB6, was obtained as a black crystalline powder by H.
Strontium carbide, SrC2, is obtained by heating strontium carbonate with carbon in the electric furnace.
Strontium carbonate, SrCO 3, found in the mineral kingdom as strontianite, is formed when a solution of a carbonate is added to one of a strontium salt.
Strontium salts may be recognized by the characteristic crimson colour they impart to the flame of the Bunsen burner and by the precipitation of the insoluble sulphate.
On the preparation of pure strontium salts, see Adrian and Bougarel, Journ.
Recent determinations of the atomic weight of strontium are due to T.
Chem-., 1905, 47, p. 1 45), who, by estimating the ratios of strontium bromide and chloride to silver, obtained the values 87.663 and 87.661.
At the same time any lead, calcium, barium and strontium present are precipitated as sulphates; it is therefore advantageous to remove these metals by the preliminary addition of sulphuric acid, which also serves to keep any basic iron salts in solution.
In a smaller degree these alkaline properties are shared by the less soluble hydrates of the "metals of the alkaline earths," calcium, barium and strontium, and by thallium hydrate.
In its chemical properties it closely resembles barium and strontium, and to some degree magnesium; these four elements comprise the so-called metals of the "alkaline earths."
Detection and Estimation.-Most calcium compounds, especially when moistened with hydrochloric acid, impart an orange-red colour to a Bunsen flame, which when viewed through green glass appears to be finch-green; this distinguishes it in the presence of strontium, whose crimson coloration is apt to mask the orange-red calcium flame (when viewed through green glass the strontium flame appears to be a very faint yellow).
Ammonium chlorate, NH 4 C10 3, is obtained by neutralizing chloric acid with either ammonia or ammonium carbonate, or by precipitating barium, strontium or calcium chlorates with ammonium carbonate.
Sodium, potassium and strontium chlorides for sodium extraction), as these melt at a lower temperature than the pure chloride.
The most commonly used salt is the iodide of potassium; the iodides of sodium and ammonium are almost as frequently employed, and those of calcium and strontium are in occasional use.
Strontium also gives triplets, but only the side branch series has been observed.
Calcium, barium and strontium; the most stable acidic hydroxides are those of the elements placed in groups VB, VIB and Viib of the periodic table.
Strontium hydride behaves similarly.
Soc. chim., 1902, 27, p. 1141); calcium and strontium similarly form hydrides CaH 2, SrH 2 at a dull red heat (A.
The figures for the more important minerals are as follows: Gold ore, manganese ore and uranium ore are produced in small quantities, and the list of minerals worked in the United Kingdom also includes chalk, lead, alum, phosphate of lime, chert and flint, gravel and sand, zinc ore, gypsum, arsenic, copper, barytes, wolfram and strontium sulphate.
It combines with chlorides of the alkali metals to form double salts, and also with barium, calcium, strontium, and magnesium chlorides.
Excepting strontium, those which are low upon the list are represented also by lines of small intensity.
Dyson has measured some eight hundred lines in the lower chromosphere and identified them with emission spectra of the following elements: hydrogen, helium, carbon with the cyanogen band, sodium, magnesium, aluminium, silicon, calcium, scandium, titanium, vanadium, chromium, manganese, iron, zinc, strontium, yttrium, zirconium, barium, lanthanum, cerium, neodymium, ytterbium, lead, europium, besides a few doubtful identifications; it is a curious fact that the agreement is with the spark spectra of these elements, where the photosphere shows exclusively or more definitely the arc lines, which are generally attributed to a lower temperature.