LliSSO.NS IN' CH1..MI 



T t? ^ i \ v vj iv i 1 1 I. 1 \l I < T I V V I V *>''"" (SrCO.) in called Ntrvntianite, since it 



LESSONS IN < 11 L.MlblKY.- A I , Argyleshire, and hence the name of 



CLASS 11. METALS OJTHJ i:I(M, ,). , ;,. II)( .,.t. 



Thu nitrate and chloride are both soluble in water, and are 

 used by pyrotechnists to impart to their fire* the splendid 

 crimson colour. The favourite red fire is a mixture of forty 

 part* of Btrontium nitrate, seven of potassium chlorate, thirteen 



i.' ii M. A.M> MALM 



BAKIUM. 

 SYMBOL, B COMBIMINO WEIUUT, 



187. 



OK thin metal in a free state but little is known. It may be 

 got by tho action of electricity on fused barytio chloride, tho 

 negative wire dipping into a globule of mercury, which in in tho 

 fused salt, and with which tho lilM-rutcd barium forma an 



.'.n. Tho mercury being driven off by hoat, barium is 

 n.l as a powder. Thin process must bo conducted in an 

 atmosphere not containing oxygen. 



;ln (BaO) is best obtained by decomposing barium nitrate 

 by hoat. It is a grey, porous ma, which combines energeti- 

 cally with water, forming tho hydrate BaO,H.,O. This com- 

 pound is to some extent soluble in water, which then forms 

 barytio water, and offers a delicate test for carbonic and sul- 

 phuric acids, barium carbonate and sulphate being white in- 

 soluble powders, which fall as precipitates. When barytic 

 water is evaporated, crystals of this composition are deposited 



BaO.U.O + 8H 3 0. 



Barytic Peroxide (BaO a ) has twice been alluded 

 to. It ia produced when baryta is heated to a red 

 heat in an atmosphere containing oxygen. 



Barium Chloride (BaCl a ) is obtained by dis- 

 solving barium carbonate in hydrochloric acid. 

 It may be obtained in crystals containing two 

 atoms of water of crystallisation. A solution of 

 this salt is a usual test for sulphuric acid, with 

 which it forms a white precipitate insoluble in 

 nitric acid. 



Barium Sulphate (BaS0 4 ), or Heavy Spar, is 

 the principal native mineral of baryta. From 

 its high specific gravity, 4'59, the element has 

 taken ita name (fiapvs, heavy). It occurs in 

 veins in mountain limestone. It is utterly in- 

 soluble in water and all acids except boiling sul- 

 phuric acid. It is used as a permanent white by 

 water-colour artists, and is the chief adulterate 

 of white lead. 



Barium Carbonate (BaCO,), or Witlierile, is 

 abundantly found in the lead mines in tho north 

 of England. At a high heat it will part with 

 its carbonic acid, leaving barytes (BaO). 



of sulphur, and four of sulphide of antimony ; but the greatest 

 caution inunt be used in ita preparation. 



CALCIUM. 



SYMBOL, Ca COXBIXIVO WKIOHT, 40 SPECIXIC GRAVITY. I'M. 

 This metal may be got by the decomposition of its chloride by 

 the galvanic current. It is of a light-yellowish colour, rather 

 softer than lead, melts at a red heat, and is malleable. The 

 salts of this metal occupy a prominent place in the composition 

 of the earth's crust. 



Calcium Oxide (Lime), CaO. This, the only oxide, is obtained 

 by heating to redness any carbonate of lime. This process 

 is usually carried on in a lime-kiln, which is an egg-shaped 

 cavity, with a fire-grate at the bottom. Chalk or limestone is 

 flung into the kiln, and the fire kept burning for three days and 

 nights. The carbonic acid is driven off, and lime 

 left. In this condition it is said to be quicklime. 

 \V hen water is added to it, the two chemically 

 combine, forming 



Slaked Lime, or the Hydrate of Lime (CaO,H,O). 

 During this process great heat is evolved, which 

 has often proved sufficient to set fire to carts or 

 ships laden with quicklime. Quicklime is soluble 

 in 700 parts of cold water, forming lime water. 

 When the hydrate of lime is mechanically diffused 

 through water, milk of lime is produced. 



Mortars and Cements. Slaked lime, when 

 mixed with water, becomes a solid as it dries, 

 but in this state it cracks and falls to pieces. 

 Tho addition of sand is found to remedy this ; 

 hence ordinary mortar is prepared by mixing 

 into a paste one part of lime and three parts of 

 tolerably fine sand. The hardening of mortar is 

 scarcely understood. However, it is mainly due 

 to the absorption of carbonic acid from the air, 

 tho lime thus returning into its original state of 

 carbonate. There is also some action between 

 the sand and tho lime, in which a silicate of 

 lime is formed. 



When lime contains from 20 to 30 per cent, of 



Barium Nitrate (Ba2NO 3 ) may bo prepared by J?IG. 40. a, QUARTZ CRYSTALS; finely-divided silica or clay, it possesses the pro- 

 dissolving the carbonate in nitric acid. b, FLUOR SPAR ; c, CALC 

 Barium Sulphide (BaS) is obtained by heating SPAR. 



finely-ground coal mixed with barium sulphate. 

 A solution of this salt dissolves sulphur, forming BaS s (barium 

 penta-sulphide). If cuprio oxide be added to a solution of the 

 sulphide, tho copper takes the sulphur, leaving the hydrate of 

 baryta in solution. 



There are some other salts of less moment. All the salts 

 of barium are colourless, and those which are soluble are 

 powerful poisons. They are all recognised by giving tho heavy 

 white precipitate with sulphuric acid. They tinge the alcohol 

 Same yellow, and the spectrum of barium is characterised by 

 green lines. Barium is distinguished from strontium by yield- 

 ing no immediate precipitate with oxalic acid. After some 

 time, however, tufts of acicular crystals of barium oxalato are 

 deposited. 



STRONTIUM. 



SYMBOL, Sr COMBINING WEIGHT, 87'5. 



Strontium closely resembles barium, but is found in much 

 loss quantity. The metal may be procured in tho same way 

 as barium, and is found to be malleable, possessing a pale- 

 yellow colour. Its chief sources are tho sulphate (celcsline) and 

 the carbonate (strontianite). 



Strontia (SrO) is obtained by heating tho nitrate. It slakes 

 with water like baryta. There is no peroxide of strontia. 



Strontium Sulphate (SrSOJ owes its mineralogical name of 

 celestine to the delicate blue tint which many of its specimens 

 possess. It is frequently found with heavy spar. It is slightly 

 soluble in water, which solution is capable of precipitating 

 barytic salts. 



61-N.E. 



perty of hardening under water. The cause of 

 the solidification of this, an hydraulic mortar, 

 appears to be the formation of a compound with 

 silica and alumina, which is insoluble in water. 



Roman Cement is one of these hydraulic mortars, and is a 

 porous, volcanic material, originally obtained at Puzzuoli, near 

 Naples. It is now chiefly prepared from nodules of septaria, 

 which are dug out of beds of clay in the valley of the Thames, 

 on the coast of Yorkshire, and in other localities. 



Portland Cement is made from clay obtained in the valley of 

 the Medway, four parta of which are mixed with one part of 

 chalk, and these thoroughly ground together with water ; the 

 mixture ia then dried and burnt, the mass ia again ground, 

 and when mixed with water, forma a cement of great hardness. 

 It derives its name from the fact that when dried it resembles 

 Portland stone. 



Calcium Carbonate (CaCO s ) appears aa chalk, limestone, 

 marble, and coral. It also composes the shells of animals, 

 eggs, etc. When crystalline, it is known as calc spar, and, if 

 transparent, aa Iceland spar. The crystals are rhombohedrons 

 of the hexagonal system, by which it ia readily distinguished 

 from quartz and from fluor-spar. In Fig. 49, a represents a 

 cluster of quartz crystals, which are six-sided pyramids termi- 

 nating in prisms ; b are crystals of fluor-spar, which are cubes, 

 all the angles being right angles ; c represents a crystal of calo 

 spar, which ia a rhombohedron. 



Iceland Spar possesses the property of double refraction 

 that is, when a ray of light traverses it in any save one direc- 

 tion, the ray is divided into two. The phenomenon is exhibited 

 by the parallel horizontal linos in Fig. 49c. 



