178 



THE POPULAR EDUCATOR. 



unstable. When their solutions are boiled, the corresponding 

 manganous salt is formed. 



Binoxide, Deutoxide, or Peroxide (Mn0 2 ), ia the pyrolusite of 

 the mineralogist, the "manganese" of commerce. It is used 

 in the laboratory in the preparation of oxygen and chlorine. 

 When heated, it gives off one-third of its oxygen, and becomes 

 the red oxide 



3MuO 2 = (Mu 2 3 ,MnO) + O a . 



When heated with strong sulphuric acid, half its oxygen comes 

 off, thus 



MnO 3 + H.,80* = MnSO 4 + H a O + O. 



The commercial value of this black oxide depends upon the pro- 

 portion of chlorine which it will liberate from hydrochloric acid, 

 and this again is dependent on the quantity of oxygen pre- 

 sent, which is over and above that requisite to make the ore a 

 protoxide, for pyrolusite and psilomelane are never pure deut- 

 oxide. This is estimated on the principle that black oxide 

 of manganese is decomposed in the presence of free sulphuric 

 and oxalic acids. The oxygen which is liberated as the salt 

 becomes a protosulphate (MnO,SO.,), attacks the oxalic acid, 

 causing it to become carbonic acid, thus 



C a O 3 + O = 2CO 3 . 



By allowing this CO 2 to pass through a weighed potash tube, 

 its quantity may be estimated, and therefore that of the 

 binoxide in the sample of ore. 



Manganic (H 2 MnO + ) and Permanganic Acid (H s Mn 2 8 ). 

 When equal weights of caustic potash and manganese peroxide 

 in fine powder are fused together, a bright-green mass is formed ; 

 this is potassium manganate. It forms a dark-green solution, 

 which, when diluted, slowly passes through purple to a claret 

 uolour, and hydrated manganic dioxide is found to be deposited. 

 The cause of this is that the manganate absorbed oxygen, 

 becoming a permanganate. Owing to these changes of colour, 

 it has acquired the name of mineral chameleon. A solution 

 of potassium permanganate readily oxidises organic matter ; 

 hence it ia used as a disinfecting agent, as Candy's Fluid. The 

 presence OL manganese is easily detected by " Cram's test." Add 

 to the suspected body a little dilute nitric acid, and a little 

 peroxide of lead ; if any manganese be present, the red colour 

 of permanganic acid will be produced. A bead of borax becomes 

 violet if manganese be present in the oxidising flame of the 

 blow-pipe, but the colour is lost in the reducing flame. With 

 carbonate of soda, the salts of this metal give a bluish-green 

 opaque bead in the blow-pipe flame. 

 IRON. 



SYMBOL, Fe COMBINING WEIGHT, 56 SPECIFIC GRAVITY, 7'8. 



This, the most important of all the metals, is never found 

 native, except in " meteoric stones." Its ores are plentiful, and 

 widely diversified. The chief are 



Magnetic Iron Ore, Loadstone (Pe 2 O 3 ,FeO). It occurs in the 

 Swedish mountains, and in North America. Most of the cele- 

 brated Swedish iron is from this ore. It is found in masses in 

 the primary rocks ; and therefore, coal being absent, wood ia 

 used in its reduction, which fact contributes to the fine quality 

 of the metal it yields. The Iron Sand, found in India and New 

 Zealand, belongs to this class of ore. It is the only ore of iron 

 which occurs in any quantity capable of magnetism, and is 

 magnetised by the influence of the earth's magnetism in its 

 original state ; hence the properties of the loadstona. 



Specular Iron Ore (Fe 2 O 3 ). This is found in Elba, Eussia, 

 and Sweden, and gives iron of a fine quality. 



Red Haematite is another form of the peroxide. It is some- 

 times found massive, but generally as fibrous, crystallised 

 nodules, which, from their colour and smooth mammillary sur- 

 face, have obtained for this ore the name of the " kidney ore." 

 It is seldom smelted alone, but generally with the clay ore. 



Brown Haematite is another variety of the peroxide, which is 

 found in later deposits known as pea-iron ore. 



Spathic Iron Ore is a carbonate of the metal, and so also is 

 the great source of English iron 



The Clay Iron Ore. This is found in bands Jn the coal 

 deposits. It contains about 30 per cent, of the metal, the rest 

 of its bulk being clay, lime, and magnesia. 



The Bog Iron Ore contains phosphate of iron, and, as its name 

 indicates, is found in alluvial tracts. 



Iron Pyrites (FeS 2 ), though very abundant, is never worked 

 for iron, but for sulphur. 



REDUCTION OF IRON FROM THE CLAY IKON ORE. We 

 may conveniently divide this operation into four stages . 



1. Roasting. The ore, mixed with coal, is piled in large 

 heaps, and a fire is kindled to the windward, which gradually 

 extends through the mass. This heat expels all moisture and 

 carbonic acid gas. The " calcined ore " is left in a porous state, 

 containing iron as an oxide. This process requires montha 

 for its completion. 



2. Smelting. The blast furnace is a structure, as in Fig. 50 r 

 about fifty feet high. It is built of solid masonry, and lined 

 with fire-bricks. The lower part of the cone contracts into the 

 crucible, E F. Below the tuyeres, or blast-pipes, the furnace 

 terminates in the hearth G, where the melted metal collects pre- 

 viously to being drawn off ; M is the tymp stone, over which the 

 slag runs down, and thus leaves the furnace ; T and F are the 

 tuyeres. At the lowest point of the furnace is the tap-hole by 

 >vhich the metal is drawn off. The calcined ore contains chiefly 

 o,vidc of iron, silica, and clay. No amount of heat will separate 

 these infusible bodies from the iron ; hence it is necessary to add 

 lime in order that a fusible slag may be found. Thus the fur- 

 nace is charged with alternate layers of coal, limestone, and ore. 

 The air which forms the blast is driven by fans, and caused to- 

 pass through heated tubes, so that when it issues from the tuyeres 

 its temperature is about 350 Cent. If cold air were used, it 

 would seriously detract from the heat of the furnace, for as 

 much as sie tons of air pass through in an hour. The oxygen of 

 tho blast at once combines with the carbon of the fuel in that 

 part of the furnace called the "boshes," i>, and becomes car- 

 bonic acid gas ; ascending a little higher in the furnace this gas 

 as in an ordinary fire takes an atom of carbon, becoming- 

 carbonic oxide, which, mixed with nitrogen and carburetted 

 hydrogen, rises through the furnace. In the presence of these- 

 gases, tho iron in the ore becomes reduced, but the tempe- 

 rature at that part of the furnace is not sufficient to melt the 

 iron, or make the silica and lime fuse together. But when the 

 charge sinks down into tho crucible, the fusion of the slag is 

 determined, and the iron, which is in a finely-divided state, com- 

 bines with the carbon, and fusee into the ciniiide of iron, known 

 as cast-iron. This falls to the bottom of the crucible, and the 

 slag, which is five or six times the bulk of the iron, swims 

 upon it, and preserves it from the action of the air of the 

 blasts. Aa the slag accumulates, it rises to the level of the 

 tyuip stone, over which it flows to N, where it is received into an 

 iron box, and is thus removed. The iron is drawn from the 

 furnace once in twelve hours, and run into sand-moulds, and 

 finds its way to the market as pig-irmi. A blast-furnace- 

 continues in action for six or eight years uninterruptedly. 



LESSONS IN GERMAN. XL. 



SECT. LXXXI. VARIOUS IDIOMATIC PHRASES (continued). 

 9?UI)t?, or irictyt tnfur fonnen, signifies " not to be in fault, or to- 

 blame," as : 3d) fann nirfjtS t-afiiv, it is not my fault, or I cannot 

 help it (literally, I cannot, or can nothing therefore). @t faim 

 nictytS fcafut, tap ft fo arm tft, he cannot help it that is, he is not 

 to blame that he is so poor. So also interrogatively ; as : Jlaim 

 tic SBclt etn?a tafur, taji fid; fin griper @cift in ein fd;lcd;tcS JUcit 

 uftffcrft ? (3JaOencr) is the world to blame, that a great soul con- 

 ceals itself in a plain dress ? that is, >ie 28ctt fann nid;t tafiiv. 



Jln'gcbcn, to give, spe- 

 cify. 



Sln'firciujung, /. exer- 

 tion, effort, labour. 



S3ctett', ready. 



3ctuf, in. calling, vo- 

 cation. 



SBcvu'fiigen, to quiet. 



SBcfttm'mcn, to fix, de- 

 termine. 



3? a fur', therefore, for 

 it. 



3)anf, m. thanks, ac- 

 kno wl edgment. 



Qrrtet'tcn, to save, res- 

 cue, deliver. 



Surest, /. fear, dread. : 



