202 



CHLORANTHACE.E 



CHLORINE 



hypnotic it is most valuable in cases where opium 

 or morphia is dangerous or undesirable ( in children, 

 in disease of the kidneys), and where sleeplessness 

 is combined with excitement (delirium of fevers, 

 delirium tremens, insanity ) ; but it may be em- 

 ployed in many other cases with advantage. In 

 tetanus (lockjaw), and other diseases attended by 

 convulsions, it is often of great value. It acts as 

 an antidote in poisoning by strychnia and Qalabar 

 bean. It mus"t be employed with the greatest 

 caution, or not at all where there is any reason to 

 suspect weakness of the heart, or embarrassment 

 of the circulation from any other cause ; in such 

 cases dangerous symptoms are very readily produced 

 by it. When habitually employed to procure sleep, 

 it is generally less hurtful than opium ; but some- 

 times ' profound melancholy and enfeeblement of 

 the will, muscular lassitude, inability to sleep 

 without the drug,' and other untoward symptoms 

 ( called collectively chloralism ) result, and only 

 disappear when its use is discontinued. Moreover, 

 fatal accidents from its indiscriminate use are far 

 from uncommon. Poisoning by chloral should be 

 treated by keeping the patient warm, attempting 

 to rouse him, administering coffee and small doses 

 of strychnia or atropia. 



When chloral hydrate is treated with caustic 

 potash, pure chloroform is obtained ; but owing to 

 the expense, this process has not come into use in 

 Great Britain. It has been supposed that its 

 anfesthetic property is the result of a similar 

 formation of chloroform in the blood, but no 

 evidence of this is forthcoming. 



Clllorantha'cese, a small group, chiefly tropi- 

 cal, allied to the peppers, aromatic and stimulant. 

 Chloranthus imonspicuns is the Chu-lan of the 

 Chinese, who use it for perfuming teas. 



Chloric Acid, HC1O 3 , is the acid correspond- 

 ing to the hypothetical oxide of chlorine, repre- 

 sented by the formula C1 2 O 5 . It is a syrupy liquid, 

 with faint chlorine odour and acid reaction. A 

 piece of paper dipped into it becomes charred and 

 takes fire, and it is instantly decomposed by con- 

 tact with organic matter. In itself it is not of 

 much importance, but it forms a class of salts 

 called chlorates, one of which at least is well 

 known. Chlorate of potash, KC1O 3 , is an article 

 of commercial value, and may be prepared by pass- 

 ing chlorine into a solution of caustic potash, heat- 

 ing the liquid, and crystallising out the salt. It 

 forms pearly plates, which, when heated, melt and 

 give off oxygen in abundance. So also when 

 thrown on red-hot charcoal, oxygen is given off, 

 and violent deflagration ensues. On account of 

 this property it is used in the preparation of 

 coloured fires, but its use is not unattended with 

 danger, owing to their tendency to spontaneous 

 combustion and its explosive properties when 

 triturated with sulphur. Mixed cautiously with 

 amorphous phosphorus, previously moistened with 

 alcohol, it forms a mixture which, when dry, ex- 

 plodes if tapped with a pencil. This mixture is 

 employed in the manufacture of some kinds of 

 matches, which give a slight explosion when struck. 

 If a crystal of chlorate of potash be placed on a 

 piece of paper saturated with turpentine, and a 

 drop of sulphuric acid added, it causes the in- 

 flaming of the turpentine with explosive rapidity. 

 The chlorate is also used in medicine, and in a 

 compressed form has become a popular remedy in 

 certain forms of sore throat. 



Chlorillietry is the process of estimating the 

 proportion of ' available chlorine ' in Bleaching 

 Powder (q.v. ), which may vary from 20 to 40 per 

 cent. The term available applies only to that 

 portion of the chlorine which is easily liberated, 

 and which takes part in the bleaching process. 



Chlorine, which is present as chloride, as in chlo- 

 ride of calcium, CaCl 2 , has no bleaching power, and 

 is not estimated by chlorimetry. 



The process is one of volumetric analysis, and 

 the apparatus used is similar to that described in 

 the article on Analysis (q.v.). There are several 

 practical methods or chlorimetry, all based on the 

 principle of measuring the oxidising power of the 

 bleaching powder. This is arrived at by making 

 a solution containing a definite amount of pure 

 sulphate of iron, arsenious acid, or other substance 

 capable of being oxidised, running in the solution 

 of bleaching powder very slowly, and then by 

 suitable tests determining the exact point when 

 oxidation has taken place. By calculation the 

 amount of ' available chlorine ' is at once obtained. 

 Where substances other than bleaching powder 

 are under examination, slight modifications of the 

 process may be necessary. 



Chlorine ( sym. Cl ; atom. wt. 35 '5; Gr. chloros, 

 ' pale green ' ) is a non-metallic element discovered 

 by Scheele in 1774, and named by him dephlogisti- 

 cated marine air. Afterwards, in 1810, Davy 

 proved it to be an elementary body, and gave it the 

 name which it now bears. In nature it is always 

 found in a state of combination. United with 

 sodium, Na, it occurs very largely as the chloride 

 of sodium, NaCl common salt in the ocean ; in 

 large beds, as rock-salt ; in all natural waters, 

 including even rain-water ; in clays, soils, lime- 

 stone ; in volcanic incrustations ; and in the vege- 

 table and animal kingdoms. The preparation of 

 gaseous chlorine by its liberation from common 

 salt, is described under HYDROCHLORIC ACID and 

 SODA. See also BLEACHING POWDER, which is 

 the form in which chlorine is prepared commer- 

 cially. For experimental purposes the gas may 

 be received in jars filled with warm water at the 

 pneumatic trough, when the chlorine rises into the 

 jar, and displaces the water. When thus obtained 

 it is a yellowish-green gas with a peculiar and 

 suffocating odour, is not combustible, and is a very 

 feeble supporter of ordinary combustiog. A lighted 

 candle placed in it burns with a very smoky name, 

 owing to the hydrogen of the oil alone burning, while 

 the carbon is liberated. Several of the metals, 

 such as antimony, copper, and arsenic, in a fine 

 state of division, or in the condition of thin leaves, 

 at once become red hot, and burn when introduced 

 into the gas. A piece of thin paper soaked in 

 turpentine likewise bursts into flame. Chlorine is 

 a very heavy gas, nearly 1\ times heavier than air, 

 its specific gravity being 2 '470 ( air = 1 '000 ) ; it is 

 soluble in cold water to the extent of two volumes 

 of chlorine in one of water, and yields a solution 

 resembling the gas in colour, odour, arid other 

 properties. The principal properties of chlorine 

 are those of a bleacher of cotton and linen (see 

 BLEACHING) and a most powerful Disinfectant 

 (q.v.). The gas can be condensed by pressure and 

 i cold into a transparent dark greenish-yellow limpid 

 liquid, with a specific gravity of 1*330 (water 

 = 1 '000 ), which also possesses bleaching properties 

 and a most powerful odour. On the animal system 

 chlorine acts, in very minute quantity, by produc- 

 ing a sensation of warmth in the respiratory 

 passages, and increasing the expectoration ; in 

 large quantity, by causing spasm of the glottis, 

 violent cough, and a feeling of suffocation. The 

 workrnen in chemical manufactories, who get 

 accustomed to the chlorine in small quantities, 

 are generally stout at least, lay on fat but com- 

 plain of acidity in the stomach, which they correct 

 by taking chalk, and also suffer from the corrosion 

 of their teeth, which are eaten- away to stumps. 

 The antidotes to the evil effects of the introduction 

 of chlorine into the lungs are the inhalation of the 

 vapour of water, alcohol, ether, or chloroform ; but 



