CHLORIDES. 361 



colouring agent of the modern process of bleaching, which as it 

 is generally conducted with cotton goods, consists of the fol- 

 lowing operations. The cloth, after being well washed, is 

 boiled first in lime-water and then in caustic soda, which remove 

 from it certain resinous matters soluble in alkali. It is then 

 steeped in a solution of chloride of lime, so dilute as just to 

 taste distinctly, which has little or no perceptible effect in whiten- 

 ing it ; but the cloth is afterwards thrown into water acidulated 

 with sulphuric acid, of sp. gr. between 1.010 and 1.020, when 

 a minute disengagement of chlorine takes place throughout the 

 substance of the cloth, and it immediately assumes a bleached 

 appearance. The cloth is boiled a second time with caustic 

 soda, and digested again in dilute chloride of lime, and in dilute 

 sulphuric acid as before. The acid favours the bleaching action, 

 and is required besides to remove the caustic alkali, a portion of 

 which adheres pertinaciously to the cloth. The fibre of the 

 cloth is not injured by dilute sulphuric acid, although digested 

 in it for days, provided the cloth is not allowed to dry with the 

 acid in it, or left above the surface of the liquor. But it is 

 very necessary to wash well after the last souring, to get rid of 

 every trace of acid, with which view the cloth may be passed 

 through warm water, as a precautionary measure to finish 

 with. 



When employed for the purpose of disinfecting the wards of 

 hospitals, chlorine is most conveniently evolved from chloride 

 of lime, of which a pound may be mixed with water in a hand- 

 bason, and a pound measure of hydrochloric acid poured upon 

 it. The gas is evolved from these materials without heat. 



Chlorides. Chlorine combines with all the metals and in the 

 same proportions as oxygen. With the exception of the chlo- 

 rides of silver and lead, and subchlorides of copper and mercury, 

 these compounds are soluble and sapid, and they possess in an 

 eminent degree the saline character. Indeed common salt, the 

 chloride of sodium, has given its name to the class of salts, and 

 chlorine is the type of salt-radicals or haloyenous (salt-producing) 

 bodies. Chlorides of metals belonging to different classes often 

 combine together and form double chlorides ; the chlorides of 

 the potassium family, in particular, with some chlorides of the 

 magnesian family, as with chloride of copper, with chloride of 

 mercury, with both the chlorides of tin, and with perchlorides 

 generally. A chloride and oxide of the same metal (excepting 



