358 



CHLORINE. 



A somewhat different process for the preparation of chlorine 

 is generally followed on the large scale. About 6 parts of man- 

 ganese with 8 of common salt are introduced into a large leaden 

 vessel, of a form nearly globular, as represented in the figure, 

 and 5 or 6* feet in diameter, and to these are added as much of 

 the unconcentrated sulphuric acid of the leaden chambers, as 

 is equivalent to 13 parts of oil of vitriol. The leaden vessel is 

 FIG. 40. placed in an iron pan, or has a outer 



casing d e, as represented in the 

 figure, and to heat the materials, 

 steam is admitted by d into the space 

 between the bottom and outer casing. 

 In the figure, which is a section of 

 the leaden retort, a represents the 

 tube by which the chlorine escapes, 

 b a large opening for introducing 

 the solid material covered by a lid, or 

 water valve, from the edges dipping 

 into a channel containing water, c a twisted leaden funnel for 

 introducing the acid, f a wooden agitator, and e a discharge 

 tube, by which the waste materials are run off after the process 

 is finished. A retort of lead cannot be used with safety, with 

 peroxide of manganese and hydrochloric acid for chlorine, 

 owing to the action of the acid upon the lead, and the evolution 

 of hydrogen gas, which produces a spontaneously explosive 

 mixture with chlorine. A material for the vessel, which might 

 be substituted for glass, is still a desideratum in that process. 

 Vessels of silver are acted upon, the chloride of silver appearing 

 not to be absolutely insoluble in hydrochloric acid. In the 

 reaction which occurs in the leaden retort, it may be supposed, 

 either that hydrochloric acid is first liberated from chloride of 

 sodium by sulphuric acid, and afterwards decomposed by per- 

 oxide of manganese, as in the preceding experiment ; or that 

 sulphates of manganese and soda are simultaneously formed, 

 and chlorine liberated in consequence, as stated in the following 

 diagram, in which the names express (as usual) single equiva- 

 lents : 



Process for chlorine ffom chloride of sodium (common salt), 

 peroxide of manganese and sulphuric acid : 



