LIME. 



471 



which can be made air-tight by strips of cloth and 

 clay lute. A window in each side enables the oper- 

 ator to judge how the impregnation goes on, by the 

 colour ot the air, and also gives light for making the 

 arrangements within at the commencement of the 

 process. As water lutes are incomparably superior 

 to all others, where the pneumatic pressure is small, 

 a large valve, or door, on this principle, is recom- 

 iiit.'iidrd to be made in the roof, and two tunnels, of 

 considerable width, at the bottom of each side wall. 

 The apartment would thus be ventilated, without the 

 necessity of the workmen approaching the deleterious 

 gas. A great number of wooden shelves, or rather 

 trays, eight or ten feet long, two feet broad, and one 

 inch deep, are provided to receive the sifted slacked 

 lime, containing, generally, about two atoms of lime 

 to three of water. These shelves are piled one over 

 another in the chamber, to the height of five or six 

 feet, cross-bars below each keeping them about an 

 inch asunder, that the gas may have free room to 

 circulate over the surface of the powder. The alem- 

 bics for generating the chlorine, which are usually 

 nearly spherical, are, in some cases, made entirely of 

 lead ; in others, of two hemispheres, joined together 

 in the middle, the upper hemisphere being lead, the 

 under one cast-iron. The first kind of alembic is 

 enclosed, for two thirds from its bottom, in a leaden 

 or iron case, the interval of two inches between the 

 two being destined to receive steam from an adjoining 

 boiler. Those which consist below of cast-iron have 

 their bottom directly exposed to a very gentle fire. 

 Hound the outer edge of the iron hemisphere a groove 

 is cast, into which the under edge of the leaden hemi- 

 sphere fits, the joint being rendered air-tight by 

 Roman or patent cement a mixture of lime, clay 

 and oxide of iron, separately calcined and reduced to 

 a fine powder. It must be kept in close vessels, and 

 mixed with the requisite water when used. In this 

 leaden dome, there are four apertures, each secured 

 by a water-lute. The first opening is about ten or 

 twelve inches square, and is shut with a leaden valve, 

 with incurvated edges, that fit in the water channel, 

 at the margin of the hole. It is destined for the 

 admission of a workman to rectify any derangement 

 in the apparatus of rotation, or to detach hard con- 

 cretions of salt from the bottom. The second aper- 

 ture is in the centre of the top. Here a tube of 

 lead is fixed, which descends nearly to the bottom, 

 and down through which the vertical axis passes, to 

 whose lower end the cross-bars of iron or of wood, 

 sheathed with lead, are attached ; by whose revolu- 

 tion the materials receive the proper agitation for 

 mixing the dense manganese with the sulphuric acid 

 and salt. The motion is communicated either by the 

 hand of a workman, applied from time to time to a 

 winch at top, or it is given by connecting the axis 

 with wheel-work, impelled by a stream of water or a 

 steam-engine. The third opening admits the siphon- 

 formed funnel, through which the sulphuric acid is 

 introduced ; and the fourth is the orifice of the educ- 

 tion pipe. The proportion of the materials for gen- 

 erating the chlorine is as follows : 10 cwt. of salt are 

 mixed with from 10 to 14 cwt. of manganese ; to which 

 mixture, after its introduction into the alembic, from 

 12 to 14 of sulphuric ffcid are added, in successive 

 portions : that quantity of acid must, however, be 

 previously diluted with water, till its specific gravity 

 becomes about 1.65. The eduction pipes from all 

 the alembics terminate in a leaden chest, or cylinder, 

 with which they are connected by water-lutes, hav- 

 ing a hydrostatic pressure of two or three inches. 

 In this general divcrsorium, the chlorine is washed 

 from adhering muriatic acid, by passing through a 

 little water ; and, from this reservoir, the gas is con 

 ducted off by one general pipe, and delivered into 



the top of the chamber containing the lime, where, 

 in consequence of its gravity, it diffuses itself equally 

 over powder spread out upon the shelves. Four 

 days are required for making good marketable 

 bleaching-powder. The manufacturer generally 

 expects from one ton of rock salt, employed as above, 

 a ton and a half of good bleaching-powder. In 

 using the chloride of lime for bleaching, the coloured 

 cloth is first steeped in warm water, to clean it, and 

 it is then repeatedly washed with a solution ot 

 caustic potash, so diluted that it cannot injure the 

 texture of the cloth, and which solution is thrown 

 upon it by a pump. The cloth is then washed and 

 steeped in a very weak solution of the bleaching- 

 posvder ; again washed, acted on by a boiling ley, as 

 before, and again steeped in the solution ; and these 

 operations are performed alternately several times. 

 The cloth is, lastly, immersed in very dilute sul- 

 phuric acid, which gives it a pure white colour ; 

 after which it is washed and dried. The chlorine is 

 known to decompose water, whose hydrogen forms 

 with it muriatic acid, which is always found in the 

 solution (after the process) when liquid chlorine is 

 used, and a muriate, when a chloride is employed. 

 In a similar manner, it is believed to decompose the 

 colouring matter, one of whose elements is always 

 hydrogen; and, its composition being thus sub- 

 verted, it disappears from the fabric with which it 

 existed. Still more important is the use of the chlo- 

 ride of lime in counteracting contagion, and all 

 noxious effluvia. MM. Orfila, Lescure, Gerdy, and 

 Hennelle, having to examine the body of an individ- 

 ual who was supposed to have been poisoned, and 

 who had been dead for nearly a month, found the 

 smell so insupportable, that they were induced to try 

 the application of the chloride of lime, as recom- 

 mended by M. Labarraque. A solution of this 

 substance was frequently sprinkled over the body, 

 and produced the effect of destroying, after a few 

 aspersions, every unpleasant odour. It was after- 

 wards used in a still more desperate case, in clear- 

 ing some offensive drains in Paris, with perfect suc- 

 cess. It was also found to be the best and most 

 durable means of disinfecting hospitals, &c. In such 

 cases, the powder is so exposed to the infected 

 region as to offer the greatest amount of surface, in 

 order that the carbonic acid of the contagious atmo- 

 sphere may expel the chlorine from the chloride of 

 lime, which it does by combining with it to form 

 carbonate of lime. A very convenient method of 

 applying it to ordinary apartments, which we are 

 desirous to free from unwholesome effluvia, is to 

 diffuse about four ounces of the powder through five 

 gallons of water, and sprinkle it over the floor by 

 means of a water-pot. 



Lime combines with the acids, neutralizing the 

 acid properties. Its salts are, in general, decomposed 

 by potash or soda, which precipitate the lime, but 

 not by ammonia. Oxalic acid throws down lime 

 from all the other acids ; and, this compound being 

 quite insoluble, oxalic acid forms the most delicate 

 test of the presence of lime. 



Carbonate of lime may be formed by adding car- 

 bonic acid to limewater, or by decomposing any of 

 the soluble salts of lime by any of the alkaline car- 

 bonates. It is very sparingly soluble in water. 

 Hence lime-water is an excellent test of the pre- 

 sence of carbonic acid. By an excess of car- 

 bonic acid, carbonate of lime is rendered sol- 

 uble. When exposed to heat, it first loses what 

 water it contains, and, if transparent and hard, 

 becomes white, opaque, and friable. If the heat be 

 augmented, the carbonic acid is expelled, and quick- 

 lime remains. The experiments of Sir J. Hall have 

 proved that if carbonate of lime be heated under 



