CHEMISTRY. 



47 



Klemenrt converted into barytes. It undergoes the same change 



of when exposed to the open air. 

 Chenuitry. 



SECT. IV. Of Slrontian. 



StrontUn, 



howob- 



lained. 



Iti proper 

 u.e. 



Strontian was first discovered in the lead mine at 

 Stroutian in Argyleshire. It was suspected to be a 

 peculiar earth by Dr Crawford in 1790, and its pro- 

 perties were soon after investigated by Dr Hope. 

 Klaproth and Kirwan also ascertained its peculiarity. 

 It is found sometimes combined with carbonic acid, 

 sometimes with sulphuric acid. From the first com- 

 pound, it may be obtained by making the mineral in- 

 to a ball with charcoal powder, and exposing it to a 

 violent heat ; and from the second, by treating it pre- 

 cisely in the way described in the last Section for ob- 

 taining barytes. 



Strontian thus obtained, is a porous mass of a 

 greyish white colour. Its taste is acrid and alkaline, 

 and it changes vegetable blues to green. Its speci- 

 fic gravity is 1.647. It is not poisonous. 



When water is thrown upon it, the Strontian be- 

 comes hot, combines with water, and is slacked like 

 quick-lime. It is soluble in water, 162 parts of that 

 liquid taking up one part of Strontian. Hot water 

 dissolves a much larger quantity, and the Strontian 

 crystallizes as the solution cools. 



Strontian does not combine with oxygen. The 

 only simple combustibles that unite with it are sul- 

 phur and phosphorus. The tulphuret and phos- 

 phuret of Strontian may be formed precisely as the 

 same compounds of lime, and possess nearly similar 

 properties. 



Strontian does not combine with azote. 



It has no action on the metals, but it combines 

 with some of the metallic oxides. It does not unite 

 with the alkalies, nor with the other alkaline earths. 



It tinges flame of a beautiful red colour. The 

 experiment may be made by setting fire to paper 

 dipt in an alcoholic solution of muriate of Strontian. 

 Strontium. Mr Davy ha* ascertained, that Strontian, like the 

 other alkaline earths, is composed of oxygen and a 

 peculiar metal, to which he has given the name of 

 tlroiitium. This metal bear* a close resemblance to 

 barium in its properties. 



CHAP. III. 



Of the Earlh* Proper. 



Of the THE earths proper neither neutralize acids, nor 



earthi pro- produce any change on vegetable blues. They are 

 per. five in number ; namely, alumina, yttria, glucina, >- 



coma, tilica. 



SECT. I. Of Alumina. 



Alumina, Alumina may be obtained from the salt called 

 alum, by the following process. Dissolve alum in 



iatoed. b " water P ur ammonia into the solution, a precipitate 

 appears ; separate this precipitate and wash it j 'then 

 boil it in liquid potash till the whole is dissolved ; 

 pour a solution of sal ammoniac into this liquid, a 



Elements 



of 

 Chemistry. 



white matter precipitates, which, when washed and 

 dried, is pure alumina. 



Alumina is a white matter in powder. It has no 

 taste, and when pure no smell. Its specific gravity i,s proper- 

 is 2.000. tic*. 



When heat is applied to alumina, it gradually loses 

 weight, in consequence of the evaporation of mois- 

 ture ; at the same time its bulk is diminished. Alu- 

 mina undergoes a diminution ot bulk proportional to 

 the heat to which it is exposed. Mr Wedgewood Wedge- 

 took advantage of this property, to contrive an in- wood's py- 

 strument for measuring high temperatures. It con- rometer - 

 sisti of pieces of clay of a determinate size, and an 

 apparatus for measuring their bulk with accuracy. 

 One of these pieces is exposed to the heat, and the 

 temperature is judged of by the contraction. This 

 contraction is measured by means of two brass rules 

 fixed to a plate. The distance between them at one 

 extremity is 0.5 inch, and at the other extremity 0.3 

 inch. These rules are 24 inches long, and divided 

 into 240 equal parti, called degrees. These degrees 

 commence at the wide end of the scale. The first 

 corresponds with 947 of Fahrenheit, or a red heat. 



Alumina is not soluble in water, though it has a 

 strong affinity for that liquid. It may be kncdded 

 with it into a very ductile paste, possessed of a good 

 deal of tenacity. Clay owe* its ductility to the alu- 

 mina which it contains. It retains water with more 

 obstinacy than any of the other earths. 



Alumina has no effect upon vegetable blues. It 

 cannot be crystallized artificially, but it is found na- 

 tive in beautiful crystals, constituting the precious 

 stone called sapphyr. 



It neither combines with oxygen, nor with any of 

 the simple combustibles. Azote has no action on it. 



It does not unite with the metals, but it has an 

 affinity for several metallic peroxides. 



The fixed alkalies dissolve it readily when they are 

 in a state of solution in water ; but they do not melt 

 with it when heated in a crucible. Barytes and 

 Strontian combine with alumina, both when heated 

 with it in a crucible, and when boiled with it in wa- 

 ter. It has a strong affinity for lime, and easily melt* 

 with it when it exceeds the lime in quantity ; but 

 when the lime exceeds, fusion doe* not take place. 

 Magnesia and alumina have no action on each other. 



It is probable that alumina, like the alkaline salts, Alumium. 

 it a metallic oxide. This notion was entertained 

 long ago by chemists. Davy endeavoured to obtain 

 the metallic basis by means of galvanism, but did not 

 succeed, though he has rendered it probable that a 

 metal exists in it. To this metal he proposes to give 

 the name ofalumium. 



SECT. II. Of Yttria. 



Thi* earth was discovered by Gadoline in a Swe- Yttria, 

 dish mineral of a black colour, to which the name 

 Gadolinite has been given. To obtain it, the miner llow b * 

 al is reduced to powder, dissolved in nitro-muriatic '* 

 acid, filtered, evaporated to dryness, redissolved, fil- 

 tered, evaporated to dryness, the residual salt is heat- 

 ed to redness, redissolved in water, and ammonia pour* 

 ed into the solution. A white powder falls, which 

 i* yttria. 



2 



