LESSONS IN CHEMISTRY. 



EXBBCUB 80 (Vol. I., page 315). 



1. Avez vous ru me* MUU ? 3. Je ne le ai pas encore TOM. a. 

 -rTavez-voun apporW CMC litres ? 4. Je M ! ai pM oublUs ; je le a! 

 blue's obes mon frire. 5. Vote* mere a-t-ell appW vos scBurs ? 6. 

 Kilo ne Ion a pa* encore appeliies. 7. La domestiqua voui a-t-elle dit 

 oette nourelle ? 8. Ello m'a dit oette nouTelle. 0. Kilo me 1'a diU. 



10. Avoz-rous oublid ma coimuissiou? 11. Nous ne 1'avons pnn 

 oublit'e ; nous avons oublid yotre argent. 12. Ou avez-voua laiw>< 

 votro bourne? M. Nous 1'avons laissle chez le marcliand. 14. Avez- 

 vous acheW lea belle* gravures quo j'ai TUOS chez votre libraire? 15. 

 Je ue lea ai paa roes. 16. Votre mere lea a-t-elle achett'oa ? 17. Ello 

 uehoM dea livres, maia olio n'a pu acbete de gravures. 18. CetU 

 petite fllle u-t-ello oasse 1 mea taaaea ? 19. Elle lea a castles exprea. 

 20. Cotto dame recoit-elle aea revenus tous lea moia? 21. Elle lea 

 revolt tous lea aix mois. 22. La maison que vous avez achetee eat- 



uilo? 23. Je n'ai paa acheM de malaon. 24. Avez-vous refu 

 uuo lettre de M. votre pore bier? 25. J'ai recu une lettre de lui, il y 

 a <|tiutre jours. 26. Avez-vous parlo a oes dames? 27. Je leur ai 

 parlt*. 28. Leur avez-vous donnd des flours 7 29. Je leur en ai donne". 

 30. Les livres que vous arez aohet^s, sont-ils relies? 31. Non, Mon- 

 sieur, ils sout brochtte. 32. Avez-vous examine 1 cette maison ? 33. 

 Je ne 1'ai pas examinee. 34. Votre frere en a examine plusieurs. 



EXERCISE 81 (Vol. I., page 316). 



1. At what hour did your sister comeP 2. She came at a quarter 

 to eight. 3. Were those young ladies born in Rouen or in Caen ? 4. 

 They were born neither in Rouen nor in Caen, they were born in 

 Strasbourg. 5. Is the watchmaker at home ? 6. No, Sir, he is gone 

 to his warehouse. 7. HOB he been in Paris this year ? 8. Yes, 

 Madam, he has been there. 0. Has he bought goods there P 10. He 

 has bought jewellery there. 11. Did you go to my father? 12. I 

 went to him. 13. Has your hatter gone out to-day ? 14. He has not 

 been out, ho is sick. 15. Is the mason at home ? 16. No, Madam, 

 he is gone out. 17. When did he go out ? 18. He went out an hour 

 ago. 19. Did your hatter arrive to-day or yesterday? 20. He arrived 

 yesterday, at four o'clok in the morning. 21. Has our tailor been to 

 see his father to-day ? 22. He has left for Lyons. 23. Has not my 

 cousin's goldsmith left for Spain ? 24. No, Sir, he has returned to 

 Germany. 25. My sister has been at church this morning, and she 

 went (is gone) to school half an hour ago. 



EXERCISE 82 (Vol. I., page 316). 



1. Le meclecin est-il a la maison ? 2. Non, Monsieur, il n'est pas a 

 la maison, il est sorti. 3. Avez-vous sorti ce matin ? 4. Non, Mon- 

 sieur, je n'ai pas sorti, je suis malade. 5. La petite fllle de votre soeur 

 est-elle sortie ? 6. Oui, Monsieur, elle est sortie, elle est chez mon 

 7. A quelle heure le chapelier est-il arrive ? 8. II est arrive 1 

 hier au soir a neuf heures. 9. Le bijoutier a-t-il e'te' a Paris ou a Lyon 

 cette onnee ? 10. II a e'te 1 a Paris il y a six mois, mais il est de retour. 



11. Avez-vous 6t6 trouver mon frere ou ma soeur ? 12. Je n'ai pas eu 

 le temps d'aller les trouver. 13. Ou ce monsieur est-il ne? 14. II est 

 ne en Angleterre, a Exeter ou a Portsmouth. 15. Votre soeur n'est- 

 elle pas nee a Paris P 16. Non, Monsieur, elle est ne'e a Madrid, eu 

 Espagne. 17. M'avez-vous dit que M. votre frere avait achetd une 

 bonne maison ? 18. II a achete' une tres bonne maison a Londres. 

 19. Savez-vous a quelle heure 1'horloger est arrivd ? 20. H est arrive 

 ce matin a cinq heures moins un quart. 21. A-t-il apporte' beaucoup 

 de bijouterie ? 22. II n'a pas apportii beaucoup de bijouterie, mais il 

 a upporte 1 beaucoup de montres. 23. A-t-il e'te' en France ou en Alle- 

 magne? 24. II a etc 1 en France, en Allemagne et en Suisse. 25. M llr 

 votre sceur est-elle a la maison, Monsieur ? 26. Non, Monsieur, elle 

 est sortie, elle est allde a I'lglise. 27. A-t-elle 6t6 a 1'e'cole, hier ? 28. 

 Elle a eW a 1'eoole et a l'e*glise. 29. Y est-elle a present ? 30. Non, 

 Monsieur, elle en est revenue. 31. Le chapelier est-il arrive 1 ? 32. 

 Oui, Monsieur, il est arrive. 33. Quand est-il arrive ? 34. II est 

 arrive 1 hier, a ueuf heures du matin. 



LESSONS IN CHEMISTRY. XIV. 



BROMINE. 



SYMBOL, Br. -- ATOMIC WEIGHT, 80 DENSITY, 80. 

 IN many of its properties this element resembles chlorine, but 

 its affinities are not so strong, since it can be displaced from 

 its combinations by that gas. It owes its name to the^Bevere 

 manner in which it affects the respiratory organs. Bpu>/x* j 8 

 the Greek for " stench." It never occurs free in nature, but is 

 found combined with magnesium in sea- water, especially in that 

 of the Dead Sea. The peculiar smell of sea-weed is due to its 

 presence. Berthier discovered it in a silver ore from Mexico, 

 but it is invariably obtained from the " mother liquor " of the 

 sea. When a solution is evaporated until a film appears on 

 its surface, it is called the " mother liquid," because as soon as 

 it cools it will give birth to crystals of the salts in solution. 



Preparation. A quantity of sea- water is reduced by evapora 

 tion; the crystallisable salts, sodium chloride, etc., "crystallise 



oat;" into the "bittern" which thus remain a stream of 

 chlorine is pawed. The chlorine seizes the msgnoaipm, and 

 eta free the bromine, which give* a reddish-yellow colour to the 

 liqui'l. The bittern is now shaken with ether, which dissolves 

 the bromine and floats on the surface ; it U decanted into a glass 

 vessel ; a little caustic potash being added, potassium bromide U 

 made. This process is frequently repeated, the same ether being 

 used. The potassium bromide thus prepared is mixed with black 

 oxide of manganese and sulphuric acid in a retort ; heat being 

 applied, bromine distils over. The reaction is thus expressed 

 2BrK + 2H.SO. + MnO, = 2Br + K.SO. + MnSO. 4- H,O. 



It will be noticed that this process U identical with that of 

 liberating chlorine from common salt. 



Properties. Bromine is a liquid of a deep red colour, having 

 a density of 2-966. It boils at 47 Cent., and evaporates at all 

 temperatures. Its vapour is a dense red. If swallowed, it 

 operates as a powerful irritating poison. It bleaches more feebly 

 than chlorine, but will not support the combustion of a taper. 

 It combines with many metals forming " bromides." 



Hydrobromic Acid (symbol, HBr ; combining weight, 81 ; 

 density, 40*5). This compound cannot be made like hydro- 

 chloric acid from the combination of hydrogen and bromine in 

 the sun-light, but the elements will combine if passed through 

 a red-hot porcelain tube. It may also be obtained by decom- 

 posing' the bromide of phosphorus by water. Thus 



PBr, + 4H,O = H.PO. + 5BrH. 



The experiment is performed by a tube bent as in Fig. 44. In 

 the bend P pieces of phosphorus are placed, separated from 

 each other by fragments of moistened glass. In the bend B is 

 placed a little bromine, and the tube closed by a cork. On 

 applying a gentle heat at B, the bromine vapours pass into P. 

 where the bromide of phosphorus is formed and is decomposed 

 by the water on the glass. The hydrobromic acid thus produced 

 passes out from T. It is a colourless gas, and can be liquefied 

 under strong pressure. Its action on metallic oxides is analogous 

 to that of hydrochloric acid, forming a bromide of the metal and 

 water. 



COMPOUNDS OF BROMINE WITH OXYGEN. 



Hypobromous Acid (Symbol, HBrO). An aqueous solution of 

 this acid can bo obtained by agitating bromine water with the 

 oxide of mercury. In distilling the solution, care must be taken 

 not to raise the temperature above 30 Cent., lest the hypobromoua 

 acid should be decomposed into bromic acid and free bromine. 

 The aqueous solution of the acid is light yellow, has a sweetish 

 taste, and is a powerful bleaching agent. 



Bromic Acid (symbol, HBrO 8 ) is formed when chlorine is 

 passed into bromine water. Thus 



Br + 3H.O + 5C1 = 5HC1 + HBrO,. 



With bases this acid forms " bromates," which salts are decom- 

 posed by heat in the same way as chlorates. 



Bromine forms with hydrogen an oily detonating liquid, which 

 resembles the chloride of nitrogen. 



IODINE. 



SYMBOL, I COMBINING WEIGHT, 127 DENSITY, 127. 

 Iodine is found in the sea in really les 3 quantities than bromine, 

 but it is obtained with more ease, for the sea-weeds store it 

 in their tissues. When these are burnt, the ash, which is called 

 kelp, is broken into small fragments, digested with boiling water, 

 and the solution thus formed is evaporated down until a film 

 forms on its surface, when it is set aside to crystallise. Sodium 

 sulphates and carbonates and potassium chloride separate. 

 The mother liquor is treated with one-eighth of its bulk of 

 sulphuric acid, and after it has stood to allow the precipitates to 

 fall, and some of the sulphates to crystallise out, the clear 

 liquid is mixed with manganese dioxide, and introduced into a 

 leaden retort. Upon the application of heat, iodine passes into 

 the receivers and condenses. The reaction is 



2NaI + 2H.SO. + TTnO, = Na.SO. + MnSO + 2H.O + 21. 



Properties. Iodine is a solid, which crystallises in plates, 

 having a brilliant metallic lustre ; when a little is heated at the 

 bottom of a test-tube, beautiful violet vapours are given off, 

 which condense in the upper part of the tube into the solid 

 iodine. This colour gives the element its name, iwSrjj being the 

 Greek for violet. 



