. HI.OHIM: 



CHl.'.KIM: 



.,,. 



in the manufacture of carbonate of aoda from chloride of nodium 

 (common ilt). [SODIUM, CompoiuuU </.] 



Chlorine may also be obtained directly from chloride of lodhun by 

 heating four part* of the latter with three part* of powdered black 

 oxide of manganese and aeran part* of concentrated sulphuric acid, 

 previoui.lv diluted with an equal weight of water. The decompoaition 

 that occur* i* expreaMd in the following equation 



MnO. + NCI + MO, = MnO, SO, + N*O. SO, + Cl 



sulphur!.- 

 add. 



Chlorine. 



Sulphite of 

 MfBMa*. 



Chlorine hai a very powerful and disagreeable ...li.ur, is very suffo- 

 cating, eren when considerably diluted with air, and its tuato is 

 astringent. According to Davy, 100 cubic inches weigh In-tw.-. n r<; 

 and 77 grains at the average temperature and pressure, and with this 

 determination the experiment* of Oay-Lussac and Thenaid nearly 

 agree; its specific gravity U consequently about 2'47. Mr. Faraday 

 found that when this gas is subjected to a pressure of alnmt fo\ir 

 atmospheres, and kept CIM>!, it is condensed into a yellow limpid Suid, 

 which is extremely volatile, and which, when the pressure is removed, 

 rapidly reaanuuee the gaseous form ; its specific gravity in aliout 1'33 ; 

 iU refractive power is less than that of water ; and it is n nun-conductor 

 of electricity. Cooled to 22(1 it still remains liquid. 



Chlorine gas is absorbed and dissolved by water, and when this fluid 

 has been recently lioiled, it will take up twice its bulk of the 

 common temperatures and pressure : the aqueous solution ha- the 

 colour, smell, and taste of the gas itself. The equivalent of chlorine 

 :.". and when moist chlorine gas is exposed to a temperature of 

 32* Fahr., yellow crystals are formed, which are hytlratc ,,j ,/,/.;.. 

 consisting, according to Mr. Faraday, of very nearly 1 equivalent of 

 chlorine = 35'45 + 10 equivalents of water = 90. Neither light, In 

 electricity, produces any change in the prapertiM of chlorine gas, 

 provided it be dry ; but if it be moist , then light causes it to decompose 

 tli.' water, the hydrogen of which combines with it to form hydro- 

 chloric acid, while the oxygen is evolved in the gaseous form, and it 

 was this experiment which chiefly induced Berthollet to adopt the 

 opinion of its nature which has already been explained. In the decom- 

 ]>ositioii of the compounds which contain it, it is evolved like oxygen 

 at the positive pole, or anode; except when separated from oxygen, 

 and then it goes to the negative or cathode. 



One of the most curious and important properties of chlorine is the 

 power which it possesses of destroying the colour of animal and 

 vegetable matter in general, and hence its extensive application to the 

 purpose of bleaching. [CHLOKIMKTHY.] When acids alter vegetable 

 colours, they may in many cases be restored by the application of an 

 alkali ; but so complete is the destructive jiower of chlorine, that 

 nothing whatever can reproduce the colour which it has removed. 

 This power appears to depend upon the great affinity which exists 

 between chlorine and hydrogen, the latter element being removed from 

 the coloured compounds to form hydrochloric acid with the chlorine. 

 while more chlorine takes the place of the hydrogen and colourless 

 compounds result. 



Chlorine gas is a supporter of combustion. If certain metals, and 

 especially antimony, in the state of powder, be thrown into chlorine 

 gas, they burn spontaneously ; phosphorus also exhibits similar phc- 



Chlorine it also a powerful disinfectant ; for this purpose it was first 

 employed by Uuyton de Morveau ; compounds of chlorine, and lime or 

 soda, have been extensively used for this purpose. 



Chlorine is in general easily detected by its odour and colour, 

 whether in iU gaseous state or in solution in water. It occasion* a 

 white precipitate in solution of nitrate of silver, which speedily darkens 

 by exposure to light This compound is called chloride of silver. It 

 i* insoluble in nitric acid, even when boiled, but is readily soluble in 

 n of ammonia. By this test, however, a portion only of the 

 chlorine is thrown down; part of it uniting with the oxygen of the 

 oxide of silver forma chloric acid, of which we shall presently make 

 mention. It will be observed from the above statement that those 

 oompound* which contain chlorine are called chlorides; but this is the 



> combines with almost every other elementary body, forming 

 compounds of great importance; we shall first state the nature of 



to which it give* rise by uniting with o\ 



yyn *d CUarint combine in several proportions, but the combi- 

 is never immediate; and different views of the number and 

 nature of the compounds are entertained by different chemists The 

 important one* are five in number, 



Hrph!oroiu acid . 

 Chloroataeld 

 Ptroilde of chlorine 

 Chloric Kid 

 Perchloric acid 



CIO, 

 CIO, 

 CIO, 

 CIO, 



The other oxides of chlorine arc probably merely coin) lounds . 

 just enumerated with each other. Thus eutUonnt, discovered by Sir 

 Humphry Davy, a yellow explosive gas evolved when a chlorate U 

 gently heated with hydrochloric acid, is a mixture of chlorine with 

 < 2CIO,. CIO,). 



I ' ,clo.V--lt ha* been already mentioned that oxygen 

 and chlorine do not combine by direct action ; when however chlorine 

 meets with nascent oxygen they unite. If chlorine gas be paste, i 

 water containing oxide of silver dimmed through it, a portion of the 

 chlorine combine* with the silver and forms a chloride, which i 

 cipitated ; and the oxygen expelled from it uniting with another portion 

 of rhlorino, constitutes chloric acid, which remains in m>\ 

 excess of chlorine is to U- i-xpclled by heat. Orel, 

 made by adding dilute sulphuric acid to chlorate of baryta, in which 

 sulphate of baryta is precipitated, and chloric acid remains in 

 solution. It is a colourless inodorous acid, which has a sour taste, and 

 reddens vegetable blue colour*. The solution may be concentrated by 

 a gentle heat till it acquires an almost oily consistence ; it has 

 a yellowish tint, a peculiar odour, and it sets fire to dn 

 matters. It combines with banes to form salts term. which 



were formerly known by the name of oxygenised muriate*. 

 oxymuriates. Bodies which have a strong affinity for oxygen decom- 

 pose chloric acid, by separating that element: thus sulphurous . 

 converted into sulphuric acid by decomposing it, and taking its os 

 Chloric acid is composed of 



-ell = 4o 



JS-U 



The chlorates, except tlmt of pota.-h. arc not iin|K>rtaut salt* : thi- 

 however is used for many purposes ; thus when it is heated it evolves 

 MTV ] >uro oxygen gas, and chloride of potassium remains; the oxygen 

 is yielded both by the acid and the alkali. Chlorate of potash [POTA*- 

 SIUM] is prepared on the large scale by passing chlorine gas b 

 solution of the alkali ; i>art of the chlorine takes oxygen from part of 

 the potash and forms with it chloric acid, which unites with the 

 remainder of the potash to form the chlorate, while the remain 

 the chlorine unites with the i>tas.sium to form chloride : both salts 



in water, but the chlorate crystallises first, and in rh- 

 plates. This salt detonates when triturated with sulphur: and when 

 struck with phosphorus it explodes and inflames, and in both cases it 

 yields oxygen. 



Chlorate of potash is composed of 



1 equivalent of chloric acid 



;iiivalcut of potash . = -I*'* 1 



Equivalent 



Chlonitt iif Jlnri/t<i lUaO, CIO,) i extensively used in the maim! 

 of fireworks. 



Perchloric Acid (CIO,) is procured by the BtrtUdteon 



the chloric acid jn : >i 1 by ii 



of chlorate of potash with al>out four times '"liuric 



acid, and heating the mixture bel..w L'llT in a p..r.- ( .]ain basin: a gas, 

 which we shall presently describe, is given out. ami there remains in 

 the retort a mixture of bisulphate and pel-chlorate of jiotaidi : by 

 washing with told water the bisulphate is dissolved, and the | 

 rate remains. When this salt is mixed in a retort with half ite v 

 of sulphuric acid dibit d with one third of water, and the miv 

 heated to alnmt 280, the white vapour which arises is ]: . 

 which condenses in the receiver. 



This acid is a limpid colourless liquid, has a sharp taste, and redden - 

 litmus paper, without destroying its colour. When concentrated by 

 evaporation its specific gravity is T65, anil it then emit.- vajmur when 

 I to the air; it boils at I)'.':!", and rapidly absorbs moisture from 

 the atmosphere. When mi\e>! with sulphuric- acid and heated, the 

 acid is distilled, and it concretes on foaling into a solid, whi. i 

 tallues in prisms. It appears to bo the most stable of all the 

 pounds of chlorine and oxygen, not sufferim,' divoinpo-itioii cither by 

 the action of light, sulphurous, or hydrosujphuric acid; it dissolve* 

 iron and zinc, with the evolution of hydrogen gag. 



The salts formed by thw acid with bases are termed , 

 they are decomposed by heat, yielding much oxygen gas, and are con- 

 verted int.. chlorides. The pel-chlorates are not an important class 

 of salts. 



Peroxide of Chlorine, or Jlypneklorl.- .->;,/ (CIO,) is a gaseous 

 |Kiund evolved during i->n of perchlorat* of potash just 



described. This gas has a green colour; it has no smell of chlorine, 

 but, on the contrary, an aromatic odour; it ix readily d 

 water, to which it imparts its own colour: the solution doc. not. e..m 

 bine with alkalies; it destroys most vegetable blue colours without 

 previously redden ing them. 'When heated to 212' this gas csp 

 violently, emits a strong light, and the residual gases occupy more 

 space than the compound did which they formed; 40 volumes of the 

 gas becoming 60, of which 40 are oxygen and I!M chlorine. 



The change* which occur in thus preparing perchlorate of potash 

 and peroxide of chlorine are these : the sulphuric acid decomposing a 

 j-.ition of the chlnnite of potash evolves chloric ;.cid. which, at the 

 moment of it liberation , is separated into oxygen and > 

 chlorinit; the oxygen combines with the chloric acid of the m. 

 posed chlorate, and convert* it into perchloric acid, and conw.; 

 parohlorate of potash is formed, while the peroxide of chlorine, a 



