METALS METALLURGY. 



frequently welded to iron, so that only the actual 

 cutting portion is formed of the former. There 

 is, however, a difficulty in welding steel to wrought- 

 iron owing to the difference in their melting-points, 

 which produces an inequality in their plasticity 

 at the welding heat, and therefore the hammer 

 has a greater effect on the one than on the other. 

 From its superior strength and hardness, there is 

 little doubt that steel will yet be much more 

 largely substituted for wrought-iron as the pro- 

 cesses for manufacturing it on the large scale be- 

 come simplified and improved. Looking back for 

 but a single decade, the progress made in this direc- 

 tion is perfectly wonderful, and cannot be matched 

 by the achievements of any former period. 



In 1740, the entire quantity of iron made in 

 Great Britain is believed not to have exceeded 

 25,000 tons ; in 1802, the annual make was esti- 

 mated at 170,000; in 1828, at 702,584; and in 

 1839, at 1,512,000 tons. In 1854, the first year 

 of the carefully collected statistics now published 

 annually by the Mining Record Office, the pro- 

 duce was 3,069,838, and from that time to the 

 present it has gradually risen to nearly 8,000,000 

 tons. A very large amount of this pig-iron is 

 converted into malleable iron, as there are now 

 nearly 7000 puddling furnaces in the country. Of 

 sheet-iron for tin plates, which are principally 

 manufactured in Wales, no less a quantity than 

 130,000 tons is now annually made. On the con- 

 tinent, the iron manufacture is rapidly extending 

 in France, Prussia, Austria, Belgium, Sweden, 

 and Russia. In Sweden especially, much steel 

 is now made by the Bessemer process ; and in 

 Prussia, where spiegeleisen is produced, one single 

 maker namely, Krupp, of Essen, made in the 

 year 1882 as many as 300,000 tons of cast-steel, 

 converted in the first instance by the puddling 

 process. The great iron-smelting districts of 

 England are situated in Yorkshire, especially 

 North Riding, Staffordshire, Durham, Cumber- 

 land, Lancashire, and Derbyshire ; Glamorgan- 

 shire and Monmouthshire, in Wales; and Lanark- 

 shire and Ayrshire, in Scotland. There are no 

 iron-smelting works in Ireland. South Stafford- 

 shire is the chief seat of the malleable-iron 

 manufacture, and Sheffield of steel ; although 

 there are signs that before long Bessemer steel 

 will be most largely made in the haematite 

 districts of Lancashire and Cumberland. 



Lead. 



The use of this metal is said to be mentioned 

 in the earliest writings, and indeed the bright 

 metallic look of ordinary lead ore (galena) could 

 scarcely fail to attract the attention of the first 

 workers in metal, although native lead itself is of 

 very rare occurrence. Various minerals contain- 

 ing the metal in the state of carbonate, sulphate, 

 phosphate, or arsenate, are occasionally smelted 

 as ores of lead. The quantity of metallic lead 

 obtained from these is, however, quite insignificant, 

 compared with what is derived from galena or 

 sulphide of lead. This ore is pretty generally 

 distributed, but by far the largest supply is 

 obtained in Great Britain and Spain. In the 

 British Islands, it is found in the Silurian and 

 Devonian rocks ; most largely, however, in those 

 of the carboniferous limestone formation. About 

 one-third of the whole British produce is obtained 



from a cluster of mining districts situated near 

 the centre of that narrow portion of our island 

 which is formed by the four most northern English 

 counties. Cornwall, Derbyshire, Shropshire, and 

 Yorkshire also yield large supplies. Wales is 

 peculiarly rich in lead ore; so likewise is the 

 Isle of Man ; and the galena found there and in 

 Cornwall contains a very high percentage of silver. 

 Neither Scotland nor Ireland produces much lead. 



When pure, galena consists of 86-57 of lead 

 and 13-43 of sulphur. Several kinds of fur- 

 naces are used in lead-smelting. The Flintshire 

 one is reverberatory, and somewhat resembles 

 that shewn in fig. i. The charge, which consists 

 of about 20 cwt. of galena, is first calcined at a 

 comparatively low temperature for about two 

 hours. This converts by oxidation much of the 

 sulphide into the sulphate of lead. These react 

 upon each other on the temperature being raised 

 in the next stage, when a large quantity of lead is 

 reduced, and sulphurous acid formed. In the last 

 stage, lime is thrown in to form a stiff mixture 

 with the slag and any unreduced ore, which is 

 then drawn up the sloping sides of the furnace, 

 and remelted. In five or six hours, the charge is 

 worked off, the lead being run into a large pot, 

 and afterwards into ingot-moulds to form pigs. 



Freshly cut lead has a bright metallic lustre, 

 but, except in perfectly dry air, it soon tarnishes, 

 and turns gray by taking on a superficial coating 

 of oxide. When exposed to the atmosphere for 

 a few years, the surface becomes coated with 

 carbonate of lead. On account of its softness, lead 

 will make a gray streak on paper, and for the same 

 reason, two freshly cut pieces will adhere firmly, 

 if pressed together with some force, somewhat in 

 the same way as two pieces of iron, when pre- 

 viously softened by heat, adhere after they are 

 hammered. Lead has an extremely dull sound 

 when struck with a hard substance ; and this 

 property, as also that of a high specific gravity, 

 may be taken as rough tests of the purity of com- 

 mercial lead. It is very malleable, so that it can 

 be rolled out into thin sheets ; but it is somewhat 

 deficient in ductility, and therefore cannot be 

 drawn into fine wire. 



A very large quantity of lead is made into 

 sheets for covering the flat portions and gutters 

 of roofs, and also for lining cisterns. The lead is 

 first cast into rectangular slabs, several inches 

 thick, one of which is taken and rolled backward 

 and forward between a pair of heavy iron rollers, 

 fitted with reversing gear, until the thickness is 

 considerably reduced ; it is then divided into 

 pieces, each of which is passed again through the 

 rollers till it is brought to the required thickness. 

 Lead is also largely manufactured into pipes, and 

 this is done by using a hydraulic press to force 

 it, when melted, through an iron mould, in the 

 centre of which an iron mandrel or core is fixed. 

 Shot is made from lead alloyed with a small 

 quantity rather more than one part to a thousand 

 of arsenic, which has the curious effect of ren- 

 dering the globules more spherical. 



Lead is not acted on by dilute sulphuric acid, and 

 consequently immense chambers for the manufac- 

 ture of vitriol are now constructed of it Hydro- 

 chloric acid acts very slowly on lead, but nitric 

 acid dissolves it readily, especially when diluted. 

 Although ordinary hard water scarcely acts on 

 this metal at all, yet pure soft water to a slight 



