322 



THE POPULAE EDUCATOE. 



hydrated oxide in " malachite," " chessylite," and other copper 

 ores- 

 Copper forma with chlorine two compounds, Cuprous Chloride 

 (Cii 2 Cl 2 ) and Cupric Chloride (CuCl 2 ). A solution of the former 

 salt possesses the property of absorbing carbonic oxide gas. The 

 latter salt is formed when copper-leaf is burnt in chlorine, and 

 with two molecules of water crystallises in acicular prisms. 



Sulphides of Copper. The Cuprous Sulphide, or Subsulphide 

 (Cu 2 S), is the result of the last process but one in the reduc- 

 tion of copper from its ore. Native cuprous sulphide is occa- 

 sionally found. 



Cupric Sulphide (CuS) may be prepared artificially either by 

 heating copper and suiphur together, or by precipitation from 

 a salt of copper in solution. With iron it appears native as 

 copper pyrites. Peacock ore contains less iron. Tennantite, dark 

 ffi-ey copper ore, and silver fahlerz all contain cupric sulphide. 

 There are other cupric salts of less interest. 



The salts of copper are poisonous ; their antidote is albumen, 

 the white of eggs, with which they form insoluble compounds. 

 With potash and soda a pale blue precipitate is given. This 

 is the case also with ammonia, but with this alkali the charac- 

 teristic blue appears when it is added in excess. If iron be 

 dipped into a cupric solution it becomes covered with copper. 

 Since iron deprives the cupric salt of its acid, its surface being 

 covered with a layer of the corresponding ferric salt, and a coat 

 of metallic copper overlaying it, on account of the presence of 

 the salt between the two metals, the coat of copper shells off. 



Zinc precipitates copper as a fine black powder, which exhi- 

 bits metallic lustre when burnished. 



LEAD. 



STMBOL, Pb COMBINING WEIGHT, 207 SPECIFIC GRAVITY, 11-36. 



Galena, the chief ore of lead, is a sulphide of the metal. It 

 occurs in a cubic crystallisation, and possesses a marked metallic 

 lustre. In Cornwall it is found in the clay slates, and in Derby- 

 shire in the mountain limestone. There are mines also at Laxey, 

 in the Isle of Man. It is usually associated with more or less 

 sulphide of silver. The more imperfect the crystallisation of the 

 galena, the more sulphide of silver is present. 



The extraction of lead from galena is not difficult ; the ore is 

 separated from the gangue (the earthy matters in which it is 

 embedded) by washing, and then spread on the bed of a rever- 

 beratory furnace. Some of the sulphur burns off, the lead be- 

 coming an oxide ; some of the sulphide imbibes oxygen and 

 becomes sulphate, whilst the large portion of the ore remains 

 unchanged. When this process is sufficiently advanced, the 

 furnace doors are closed, and the heat raised to determine in a 

 manner the fusion of the ore. The lead oxide and sulphate 

 react on the galena, as shown in these equations 



2PbO + PbS = 3Pb + SO 2 

 PbSO 4 + PbS =2Pb + 2SO 2 . 



In each case the metal is liberated, and the sulphur escapes 

 as sulphurous acid gas. 



If there be much quartz present, which is generally the 

 matrix of the galena, lime is added to facilitate the liberation of 

 the metal, by causing the silica to form with the lime a fusible 

 slag. 



Extraction of Silver from Lead by Pattinson's Process. This 

 operation is based upon the fact that pure lead solidifies sooner 

 than the argentiferous compound. The lead is melted in an 

 iron pan set in brickwork, on each side of which are four or five 

 similar pans in a row. When the metal is fused the fire is 

 withdrawn, and as it cools the crystals of lead which form first 

 are removed by a perforated iron ladle, and placed in the right- 

 hand pan, the argentiferous lead being ladled into the next 

 pan to the left. The same process is repeated in all the pans, 

 the pure lead being ladled to the right, the silver lead to the left. 

 The contents of the last pan to the left are then submitted to 

 cupellation that is, the metal at a high temperature is exposed 

 to a current of air ; the lead rapidly oxidises, and the film of 

 oxide is constantly removed, until the pure silver only remains. 

 By this process it is found profitable to extract silver when 

 there is even as little as four ounces of the precious metal in a 

 con of lead. 



Properties. Lead is a bluish-white metal, very soft. It may 

 be rolled into sheets, or drawn into pipes or wire, but its tena- 

 city is low. It melts at 334 Cent. 



LESSONS IN ENGLISH. XXXIV. 



LATIN STEMS (continued). 



IT is curious to observe what a controlling influence the subject- 

 matter has in the metaphors employed and the derivations that 

 are brought into play. We lay down railways ; we set up an inn ; 

 so we set up a carriage after we have made our fortune in that 

 shop which we set up when we were poor. As we may set up 

 a shop, so may we open a shop ; but we must begin business, or 

 we may set up in business. Having built or rented, we may open 

 a warehouse, as we may open a shop. So in professions parsons 

 occupy a pulpit, and solicitors take to the desk, while barristers 

 hold briefs, and judges Jill the bench. We draw with a pencil 

 and paint with a brush. Pictures as well as books are composed, 

 and both must be sketched before they are begur ; but the 

 one ends in a painting, the other in a treatise ; the one is the 

 canvas, the other is the volume. If we are charitably inclined 

 and abound in wealth, we build a church, or found a hospital; 

 but if we expend our money for our own pleasure or convenience, 

 we erect a mansion and lay out pleasure-grounds. Probably we 

 may begin to travel, and then we make a voyage by sea and tribe 

 a journey by land. A young man entering one of the univer- 

 sities reads for honour, and studies for the church. If your eon 

 is a clergyman, he (Zoes duty on a Sunday ; but if he is a dissent- 

 ing minister, he preaches. A Methodist minister travels, a 

 minister of the Establishment is an incumbent ; the latter has a 

 living, the former is on a circuit. Lawyers advise, physicians 

 prescribe, clergymen admonish, and confessors direct. A ship 

 impelled by a steam-engine sails, a train drawn by a steam- 

 engine runs. Handicraftsmen receive their remuneration in 

 wages, clerks in salaries, lawyers in fees, and ministers of religion 

 in stipends. 



Emolument, a term always applied to the receipts of the 

 higher classes, reminds one of the time when there was in each 

 manor or vicinity one mill, the lord or owner of which received 

 as his pay either a portion of the flour there ground or its 

 equivalent in money. Hence emolument, properly that which 

 comes out of the mill-stone, came to denote gain from office or 

 high employment. 



This fact leads to the observation that words to a full mind 

 are singularly suggestive ; they are also singularly conservative, 

 keeping and tacitly transmitting from age to age facts and 

 history which relate to their origin, and have something to teach 

 respecting ancient manners and customs. Gray has said 



" The curfew tolls the knell of parting day." 

 It is equally true that the word curfew (French, couvrefeu, put 

 out the fire, or fire-extinguisher) preserves a recollection of a 

 day long since passed and gone, when the Norman, being sove- 

 reign lord of England, published his behest that at a fixed mo- 

 ment the fires of the Saxon peasantry should be extinguished. 



Stipulation (Latin, stipula, a straw) preserves an indirect 

 record of the legal custom once prevalent of presenting a straw 

 as a token of the delivery of possession to one who had pur- 

 chased an estate ; and who keeping that straw as a token of 

 his proprietorship, regarded it as the condition on which he 

 held the land. 



In the phrase "signing a deed," you have a trace of the tunes 

 when men unable to write their name, made instead the sign 

 of the cross in attestation of the part which they took in the 

 matter. 



Calculation (Latin, calculus, a little stone) recalls the old 

 custom of employing pebbles (like the little balls in the abacus) 

 by which to perform questions of arithmetic (Greek, opi0juos. 

 a-rith'-mos, a number), or the science of number. 



His library may remind the student of tho primitive period 

 when the rind or bark (Latin, liber) of trees served instead of 

 the then unknown parchment and paper. 



LATIN STEMS. 



