780 CHLORIDES 



The following process has likewise "been proscribed : Mix 10 parts of good chloride 

 of lime and water into a pap, and evaporate to dryness, whereby it is converted into a 

 mixture of chloride of calcium and chlorate of lime devoid of bleaching power; dissolve 

 it in water, filter, concentrate the solution by evaporation, then add to it 1 part of 

 chloride of potasssum, and cool for crystallisation. The salt which may thereby bo 

 separated from the chloride of calcium will afford - 83 of pure chlorate of potash. 

 By this process of Professor Liebig |ths of the potash are saved, but much oxygen is 

 wasted in the evaporation to dryness of the cloride of lime ; and consequently, much 

 chloric acid is lost towards the production of the salt. Vee mixes the chloride of lime 

 pap, before heating it, with the chloride of potassium, boils the mixture smartly, 

 whereby much oxygen is undoubtedly thrown off, and then sets the liquor acid to 

 crystallise. L. Gmelin suggests that saturation of the liquor with chlorine before 

 boiling might be advantageous. Gay-Lussac proposed to make this valuable salt by 

 precipitating a solution of chloride of lime with carbonate (or sulphate) of potash, 

 saturating the liquor after filtration with chlorine gas, evaporating, and crystallising. 



Mr. Calvert formed a mixture of 5^ equivalents of burnt lime for 1 equivalent of 

 caustic potash, and passed a current of chlorine through the hot mixture. Under 

 these conditions chloride of calcium and chlorate of potassium are produced, and the 

 quantity of the latter is stated to be very nearly the theoretical amount. 



Professor Juch's process is to pass chlorine gas into a mixture of 1 pound caustic 

 lime and 1 pound carbonate of potash, with 8 pounds of water. The resulting .chlorate 

 of potash readily separates in the filtered liquid by crystallisation from the very soluble 

 chloride of calcium. By this method potash is not wasted in the useless production of 

 chloride of potassium. 



The following process is now generally adopted for preparing chlorate of potash on 

 a large scale : An excess of chlorine gas is passed into a vessel containing milk of 

 lime at a temperature of 120 to 140 F., the liquid being kept agitated by an iron 

 stirred coated with lead. The reaction between the chlorine and the lime under these 

 circumstances results in the production of chlorate of lime and chloride of calcium, 

 with a small quantity of hypochlorite of lime ; thus differing from the reaction which 

 occurs between lime and chlorine at a lower temperature, as in the preparation of 

 ' chloride of lime.' When the gas ceases to be absorbed by the lime, the liquid is run 

 off into a tank lined with lead, where the suspended matter is allowed to subside, and 

 whence the supernatant liquid is drawn off by a siphon into a leaden evaporating pan 

 in which it is concentrated to 25 to 30 B. A hot solution of chloride of potassium 

 is then added, by which the chlorate of lime is decomposed and chlorate of potash 

 formed. Theoretically, every 168 parts by weight of caustic lime originally used 

 require 74'5 parts of chloride of potassium ; but practically one part of the chloride is 

 added for every three parts of lime. The chlorate of potash and chloride of calcium 

 are readily separated by taking advantage of the sparing solubility of the potash salt. 

 The crude chlorate is purified by solution and re-crystallization. 



Chlorate of potash, (the old oxymuriate of potash), has a cooling, somewhat un- 

 pleasant and nitrous taste ; it does not bleach. At 60 F. 100 parts of water dissolve 

 6 parts of the salt, and at its boiling point, or 220, 60 parts. When heated to dull 

 ignition in a glass retort, it gives out 39*21 per cent, of its weight of oxygen, and 

 leaves a residue of chloride of potassium. The decomposition is effected at a much 

 lower temperature if the salt be mixed with a small quantity of binoxide of manganese, 

 sesquioxide of iron, or black oxide of copper. Chlorate of potash is an active oxidising 

 agent : it deflagrates upon red hot cinders like nitre : when triturated along with 

 sulphur or phosphorus, it detonates with great violence, not without danger to the hands 

 of the operator. Similiar detonations may bo produced with cinnabar or vermilion, 

 sulphuret of potassium, volatile oils, sugar, &c ; but they can be effected only by the 

 smart blow of a heated hammer on an anvil. See LUCIFBK MATCHES and PEBCUSSION 

 CAPS. 



CHLORATES. Salts of chloric acid. 



CHLORHYDKIC ACID. The modern name for HYDROCHLORIC ACID. The 

 gas was discovered by Priestley in 1772 ; dissolved in water, it has been long known as 

 spirits of salts. See MraiATic ACID. 



CHLORIC ACID. The acid constituent of the chlorates. This acid, .which 

 is only known in combination with one equivalent of water, is exceedingly unstable, 

 being instantly decomposed by contact with organic matter, and undergoing gradual 

 spontaneous decomposition in diffused daylight. It is prepared by decomposing 

 chlorate of potash by the addition of hydro-fluosilicic acid, which forms with potash an 

 insoluble compound. 



CHLORIDES. ' The term chloride is applied to all compounds of chlorine, which 

 may be derived from one or more atoms of hydrochloric acid, by the substitution of a 

 metal or other radical (which may itself contain chlorine) for an equivalent quantity of 



