CHLORIDE OF LIME 



783 



ganese. Moreover, the oil of vitriol has a tendency to form the acid sulphate of soda or 

 bisulphate, instead of the normal sulphate, and this salt is only decomposed at a high 

 temperature. 



From the preceding computation, it is evident that 1 ton of salt with 1 ton of the 

 above native oxide of manganese, properly treated, -would yield 0'59 of a ton of chlorine, 

 which -would impregnate 1-41 ton of slaked lime, producing 2 tons of bleaching-powder, 

 stronger than the average of the commercial specimens ; or, allowing for a little loss, 

 which is unavoidable, would afford 2 tons of ordinary powder, with a little more 

 slaked lime. 



Fig. 461 represents a retort of lead, well adapted to the evolution of chlorine from 

 the mixture of salt, manganese, and sulphuric acid, or from manganese and muriatic 

 acid. 



The interior vessel is cast in lead, and it has round its bottom part a cast-iron steam 

 case. The salt and manganese are introduced by the aperture c, and the sulphuric 

 acid by the siphon-funnel /. The contact of these three substances is continually 



461 



462 



renewed by the agitator or stirrer B, which consists of wrought or cast iron, sheathed 

 with lead, e is the gas-discharge pipe. The residuums are drawn off by the bottom 

 discharge pipe G. The heating case receives its steam by the pipe h. 



The chlorine gas, is conveyed from the retort B, fig. 462, into the chamber i, by the 

 tube E E B. This chamber is divided into four compartments, to receive the gas dis- 

 engaged from four retorts, like the above. The bottom of it is covered with a stratum 

 three or four inches thick of quicklime, newly slaked and sifted, which is stirred about 

 from time to time, by the rakes 1,1,1,1,. When the saturation is sufficient, the chloride 

 of lime is taken out by the doors K x x K. The side of this apparatus allows 2 cwt. of 

 manganese, and its equivalent quantity of salt and sulphuric acid, or of muriatic acid, 

 to be introduced at once into the retort. D is the handle of the agitator. 



The same form of retort will suit perfectly well to prepare chlorine for making 

 liquid chloride of lime, which is preferred by many bleachers and calico-printers who 

 have conveniences for preparing it themselves. The most concentrated solutions of 

 the dry chloride of lime do not mark more than 6 B. (specific gravity 1'04), and dis- 

 colour only 50 volumes of Gay-Lussac's solution of indigo, whilst the chloride made in 

 the humid way marks from 8 to 9 B. (about T060), and discolours 80 volumes of 

 the same solution. 



In the chloride-of-lime apparatus, most generally used by the skilful calico-printers 

 of Miilhausen, the mixture of muriatic acid and manganese is put into glass globes, 

 with long necks, heated upon a sand-bath. The chlorine is conveyed by glass tubes 

 into a cylindrical stone cistern, containing milk of lime. The furnace of the sand- 

 baths is made of cast-iron, and has brick partitions, to give each retort its own fire. 

 The smoke of all these fires goes off by a flue into sheet-iron pipes. The cistern is 

 made of siliceous sandstone. Its cover is of wood, coated with a resinous cement ; and 

 it fits at its edges into grooves cut in the stone. A wheel serves to agitato the liquid 

 continually ; its paddles being kept at 2 inches distance from the sides of the cistern. 

 The milk of lime is introduced by a funnel, and the chloride is drawn off by a discharge 

 pipe. The lead retort and agitator used in this country seem greatly preferable to 



