LKSSONS IX CIIK.UISTKY. 



79 



the principle, time " He who in not vubmiiwivo to hi* king U uutruo to 

 lua fathurlumi r- " 19. I ahull uevor tor**t h.,w wu. h ; 



- '. Not every ouo who U rulutod to me is aUo wuU-plasinff to 

 u i ml oouoenui me, I consider ako M a matter of importance. 



KXKRCISB 93 (Vol. II., page 63). 



1. 2Btr fann tincm Jlinte fttnb ftiit ? 2. 3(1 rt 3l)ii(n gcacOm, ctntn 

 pajietsjamj $u inactieu Y 3. 3>icft ifl 3l>m (Scfodtu i^atli^. 4. 

 3fCfri!Mini u\u- thin ,ica>wen. 5. tttne <ju% X&at if* ott au: 

 0. * n i: 0>ewel;itl;nun fcfjr tyndd), tern cr ac 



abjjtnciijt ttm 9tauc$eu unb abfyolb tcm !trinn. 7. 28a mic anae^ctt, 

 lap iit> mir uuc$ anjclegtn fcin. 8. 3rtcm fcenftnttn OHanne jft tS banni* 

 Kir, t.iji f fur finen Siirftcn nit^t Itittyt ifl, fin 35otf fid) enif&ftt 511 niacfttn. 

 !>. Wit 'iu-v.imivjcn will i$ 30fn befjiilflul; fein, eine MiiflcMuna ju crl)aU 

 ten. 10. 3ci ttincn <5ltmt gef.Uliq, il;rcin 'JSUUit gcfjorfam. Mint wcr 

 tfn ftc m gcntuit nut tciiirm (Wliicfc giinfH.j Km. 11. Malted ilC.iffcr 

 ttiiifcn ift ciiicni crl'ttjtcu^orpcrfitAtlicf). 12. a qSfcrt ifl tin gdebrigtJ 

 liner unt fancm 'rcivu gdiovfani. 13. UDenn c* 30ntn an encbin ifl, 

 fonimcn ito morjtn fflJitMg ju mir. 1 t. T.cr 4?un& ifl fcincm J&mnt 

 felgfam unt trcu. 15. (Sc u>ar cjciitiijt ft.i; fcincit greuiilcu 

 ju ma$cn. 



EXERCISE 94 (Vol. II., page 94). 



1. In oldeu times, when a mighty man was hostile to another, he de- 

 I'liin . ! war against him. 2. From all places which belonged to him, this 

 mighty man collected those men who adhered to him. 3. After they had 

 assented to his purpose, they engaged to assist him, and to follow him to 

 the war. 4. Such a mighty lord was Henry the Lion, Duke of Bavaria, 

 to whom belonged large territories, and whom thousands of warriors 

 obeyed. 5. Yet the crown of an omperor always floated before his eyes. 

 6. The ducal coronet was not sufficient for him. 7. He trusted to his 

 own power, uutl defied the emperor. 8. The emperor summoned him 

 to submit to his orders, and threatened him with outlawry. 9. Yet the 

 duke, who resembled a lion, valued neither reason nor advice. 10. As he 

 till then had overcome all his enemies, he believed himself to be a match 

 for everybody. 11. He resisted the demand to render an honourtothe 

 emperor, which was due to him. 12. The emperor, who for some time 

 wished the duke ill, and on account of his pride was angry with him, 

 anticipated him, and waged war against him. 13. The warlike expedi- 

 tion was not unsuccessful for the emperor. 14. The duke could not 

 withstand the hostile power, and was defeated by the emperor in the 

 battle. 15. He was obliged to flee to England, and only his family and 

 a few of his friends followed him. 16. Here he resigned all hope, and 

 execrated pride as the cause of his misery. 17. According to your 

 wish, I will help you in looking for the horse which you have lost. 

 18. One very easily obeys a noble master, who convinces while he 

 commands us. 19. I do not relish this roast meat. 



LESSONS IN CHEMISTRY. XVI. 



SELENIUM- TELLURIUM-PHOSPHORUS. 

 SELENIUM : SYMBOL, SK COMBINING WEIGHT, 79'5 DENSITY, 79'5. 

 THIS rare element was discovered by Berzelius in the refuse of 

 a sulphuric acid manufactory, at Fahlun, in Sweden. It is not 

 found free in nature, and the source from which it is usually 

 obtained is the mineral clausthalite, in which it is combined 

 with lead although the selenidos of iron, copper, and silver are 

 the most abundant. 



Preparation. Some clausthalite is reduced to a fine powder 

 and fused with three times its weight of saltpetre, by this means 

 tho .inide (PbSe) becomes sclenate (PbSeO 4 ). The mass is 

 now digested in water, acidulated with a little hydrochloric acid 

 to neutralise any of the alkali of the nitre which may remain, 

 and the liquid evaporated down to a small bulk. A current of 

 sulphurous acid throws down the reduced selenium as a red, 

 flocculent, amorphous powder, the sulphurous acid becoming 

 sulphuric. 



Properties. It is chiefly remarkable for its close resemblance 

 to sulphur. It may be obtained, like that element, in the three 

 forms amorphous, vitreous, and crystalline. When the powder 

 of the precipitate above alluded to is dried, and submitted to a 

 temperature a little below that of boiling water, it begins to 

 soften, and a few degrees higher it melts ; upon cooling, it forms 

 a brittle solid, with a glassy fracture. Its colour is deep brown ; 

 it possesses neither taste nor smell; is insoluble in water, and 

 refuses to conduct either heat or electricity : and yet its lustre is 

 metallic. Sulphuric acid is capable of dissolving it, and is 

 rendered green ; but when diluted the selenium falls unaltered. 

 Bisulphide of carbon, at its boiling point, can hold in solution 

 l.per cent, of this element, and upon evaporation tho selenium 



is deposited in crystals. In this form tto specific gravity u 4-5, 

 whereas in the vitreou* ntte it WM 4*7. 



A third modification, oorrenponding to tlw vucid state of 

 sulphur, U obtained by sustaining the temperature of the 

 selenium at 90C. for tome hour*: it then suddenly rises to 

 1GOC. If it now be cooled, its specific ^rarity is found to be 

 4-8, iU fracture hut become granular, like cast iron, and iU 

 colour changed to bluish-grey. When thrown upon a hot coal 

 reddiuh vapoura are given off, which are characterised by their 

 peculiar Hmell that of horseradish. It burns in the air with a 

 bright blue flame, and two well-defined oxides selenio dioxide 

 ( SeOj) and selenio trioxide (8eO a ) are known. 



BeLenic dioxide, or Heleniout Acid (8eO f ; combining weight, 

 111-5), is usually prepared by oxidising selenium by means 

 of nitric acid. Tho excess of the nitric acid is expelled by heat, 

 and the white selenioua anhydroxido remains. At a temperature 

 near low red heat it will sublime in a yellow vapour, which on 

 condensing forma beautiful white acicular (needle-like) crystals. 

 These are deliquescent that is, they absorb moisture from the 

 atmosphere becoming Bclenioua acid, which forms with bases 

 the class of salts called selenites, which are all recognised by 

 emitting the horseradish odour, when heated on charcoal in 

 the blowpipe flame. 



Selenic Add (H 2 SeO 4 /. This acid is produced if, in the pro- 

 cess which has been given for procuring selenium, sulphuretted 

 hydrogen be used, instead of sulphurous acid. Thus 



PbSeO. -h H,S = H.SeO. + PbS. 



By filtering, the lead sulphide is separated ; and by evaporating 

 tho liquid until its specific gravity is 2 '6, selemc acid u 

 obtained. When heated this acid gives off oxygen, and becomes- 

 selenious acid ; it forms with bases selenates, which are tsomor- 

 phous with their corresponding sulphates, that is, they crystal- 

 lise in tho same form. 



Seleniuretted Hydrogen (symbol, H 4 Se; combining weight, 

 81'5 ; density, 4075). This gas is obtained exactly as sul- 

 phuretted hydrogen, that is, by the action of an acid on a 

 selenide. Its odour is even more offensive than that of ita 

 sulphur correspondent. 

 TELLURIUM : SYMBOL, TE COMBINING WEIGHT, 129 DENSITY, 129. 



The classes of every natural kingdom seem to gradate into each 

 other. That is, between every great division we find individuals 

 which partake of the characteristics of each class. Tellurium 

 occupies this position between the metals and metalloids, 

 whilst, from its rather high specific gravity, 6'5, some chemists 

 are inclined to rank it with the metals; yet, from its close 

 analogy to selenium and sulphur, others prefer to consider it 

 as a metalloid. It is a rare substance, sometimes found native 

 in the mines of Hungary and Transylvania, but generally it is 

 combined with gold, silver, bismuth, or copper. It possesses a 

 high metallic lustre, and resembles bismuth in appearance. A 

 high temperature converts it into a yellow vapour, which con- 

 denses in drops and flexible needles ; it is a feeble conductor of 

 heat and electricity. When strongly heated in the air it takes 

 fire, and burns with a blue flame, edged with green, into 



Tellurous Dioxide (TeO a ), which with water forms tellurous 

 acid (H 2 Te(X). Its acid properties are feeble, and it possesses 

 a bitter metallic taste. 



Telluric Acid (H s Te0 4 ) is the combination of telluric trioxide 

 and water. This trioxido is produced when the element, or a 

 tellnrite, is heated with saltpetre. Tho process is similar to that 

 by which selenic acid was procured. 



Telluretted Hydrogen (H 4 Te) is procured by the action of 

 hydrochloric acid on an alloy of tellurium with zinc or tin. It 

 is a colourless gas, having the same smell as sulphuretted 

 hydrogen. It acts upon solutions of metallic salts similarly to 

 that gas, precipitating their tellurides. 



It is usual to group oxygen, sulphur, selenium, and tellurium 

 together, since they each unite with two atoms of hydrogen. 

 The last three elements, as in the case of the three halogens, 

 exhibit a remarkable gradation, their combining weights, their 

 specific gravities, their melting and boiling points, being almost 

 in arithmetical progression that is, in everything selenium is a 

 mean between sulphur and tellurium. 



PHOSPHORUS : SYMBOL, P COMBINING WEIGHT, 31 DENSITY, 62. 



The density of the vapour of phosphorus is an exception to 

 the rule hitherto strictly regarded, for, instead of being the 

 same as its atomic weight, it is just double, or 62, and there- 

 fore the volume occupied by an atom of phosphorus is only 



