22 



(Mil: MIS TRY. 



Iron. 



Blemn) imill stream of it melted into mercury, heated nearly 

 to the boiling point ; or by keeping platei of copper 

 in a solution of mercury in mine acid. It is white, 

 and at tirst toft, but gradually hardens when exposed 

 to the air. 



SECT. X. Of Iran. 



Iron wai not known at so early a period as gold, 

 silver, and copper. The art <;f working it was dis- 

 covered in the- East, and first communicated to the 

 Greeks by the Phrygians, from whom It gradually 

 made its way through the rest of Europe. 



Properties. 1. Iron has a bluish white colour, a styptic taste, 

 and emits a tin-, li when rubbed. It is one of the 

 hardest of the metal*. Its (specific gravity varies from 

 7.6 to 7-8. It is attracted by the magnet or load- 

 stone, and is itself the substance which constitutes 

 the loadstone. When iron is perfectly pure, it re- 

 tains the magnetic virtue but a short time. 



It is malleable in every temperature, and its mal- 

 leability increases with the temperature. It cannot 

 be hammered into so thin plates as gold or silver. 

 But it may be drawn out into very tine wire. An 

 iron wire of 078 inch in diameter is capable of sup- 

 porting 549.25 Ibs. avoirdupois without breaking. 

 When heated to 158 Wedgewood, it melts ; a tem- 

 perature so high, that it is difficult to go much be- 

 yond it. 



Oxides. 2. It is much more easily converted into oxide than 



any of the metals described in the preceding Sections. 

 When left exposed to the air, especially in a moist 

 place, it is soon converted to a red or yellow powder, 

 called rutt, which is nothing else than an oxide of 

 iron usually combined with carbonic acid. When 

 kept under water, especially in warm weather, it is 

 gradually converted into a black brittle matter, which 

 is also an oxide, while some hydrogen gas is discn- 



faged, owing to the decomposition of the water, 

 f vapour of water be passed through red hot iron, 

 the iron is rapidly oxidized and much hydrogen gas 

 is obtained. If an iron wire, having a small bit of 

 lighted cotton at its extremity, be plunged into a jar 

 of oxygen gas, it burns with great brilliancy, arid is 

 converted into the ,-ame black oxide, which falls to 

 the bottom of the jar in melted drops. 



There are two oxides of iron, which have been as- 

 certained in a satistactory manner. The black oxide 

 may be obtained, by kevping iron filings a sufficient 

 time in water, by nuking steam pass through iron 

 filings at a red heat, by burning iron wire in oxygen 

 gas, IT by dissolving iron in diluted sulphuric acid, 

 and dropping potash into the solution. It is a black 

 powdrr, insoluble in water, is attracted by the mag- 

 net, and has a good deal of metallic lustre. It is a 

 compound of 78.5 parts iron and 21.5 oxygen. 



The red 01 /</<. i >r i>rro.ridr, may be obtained, by 

 keeping iron tilings red hot in an open vessel, and agi- 

 tating them constantly till they are converted into a 

 red powder ; or by exposing a solution of iron in 

 sulphuric acid for a long time to the atmosphere, and 

 then precipitating by means of potash. It is a red 

 powder, insoluble in water, and constitutes the base 

 f cvet al of the common red paints. Clay and bricks 



owe to it their yellow and red colours. It is com- 

 posed of 6!) iron and SI oxygen. 



,'t. Ir. n seems capable of combining with all the 

 simple combustibles. Hydrogen, indeed, has never 

 been united to it in a solid state, but hydrogen gas 

 dissolves a little iron, which it gradually deposits 

 when kept over water. 



Carburet of iron is found native, and is the sub- Carburet, 

 stance mentioned in a preceding Section under the 

 name of ])lnnit>tigo, or black Icail. It is a soft sub- 

 etanc", ft .1 il.irk blue colour, a granular texture, and 

 the metallic lustre. It does not burn with a flame, 

 but gradually wastes away when kept red hot. 

 When thrown into melted nitre, a very splendid 

 combustion is produced. Its tnture was first deve- 

 loped by Dr Lewis, and afterwards more fully ex- 

 plained by Scheele and the French chemists. It 

 seems to consist of about 19 parts of carbon, and one 

 of iron. 



Phosphurct of iron may be formed by dropping Photphu- 

 bits of phosphorus upon red hot iron. Its colour is reti 

 dark steel grey, it is very brittle, and does not easily 

 dissolve in acids. It exists in different ores of iron, 

 and is considered as giving to the variety of iron call- 

 ed cold short iron, the property of being brittle while 

 cold, though it be malleable while hot. Phosphuret 

 of iron was at first considered by Bergman as a pecu- 

 liar metal, and called itdenim. 



Sulphuret of iron may be formed, by melting to- Sulphurets. 

 gethrr in a crucible equal parts of iron filings and 

 flowers of sulphur. It is of a black or very deep 

 grey colour, brittle, and very hard. When the two 

 constituents of it combine, a great quantity of heat 

 is evolved, which makes the whole strongly red hot. 

 This sulphuret is composed of 63 iron and 37 sul- 

 phur. It exists native, and is known by the name of 

 magnrlir pi/rites. Its colour is that of bronze: it has 

 the metallic lustre, but its powder is blackish grey. 

 Its specific gravity is 4.518. It strikes fire with 

 steel, and easily melts when heated. It is not only 

 magnetic, but is itself capable of being converted in- 

 to a permanent magnet, as Mr Hatchett discovered. 



Iron is capable of combining with a still greater 

 proportion of sulphur, and of forming a compound 

 which may be called super-sulphuret of iron. It oc- 

 curs native in great abundance, and is known by the 

 name of pyrites, or iron pyrites. It is yellow, has the 

 metallic lustre, is brittle, strikes fire with steel, and is 

 often crystallized in cubes. Its specific gravity is 4.5. 

 When distilled, it loses its excess of sulphur, and is 

 converted into common sulphuret of iron. By this 

 process, sulphur is sometimes obtained for the purpo- 

 ses of manufactures. Pyrites is composed of 80 com- 

 mon sulphuret of iron and 20 sulphur, or more exact- 

 ly of about 47 iron and 53 sulphur. The super- 

 sulphuret is not magnetic, nor susceptible of becom- 

 ing a magnet. Mr Hatchett found, that phosphuret 

 ofiron is also capable of magnetic impregnation ; and 

 it is well known that iron containing a portion of 

 carbon, or ittcel, possesses the same property in per- 

 fection. Hence Mr Hatchett concludes, that per- 

 manent magnets consist of iron, combined with a cer- 

 tain proportion of a simple combustible. But, when 

 saturated with simple combustibles, it loses its mag- 



