298 CHLORIDES. 



748. CHLORIDE OF LIME. BLEACHING 



On what does 



the value of POWDER. The commercial article of this 

 ? name is P re P ared b Y passing chlorine gas 

 over lirne. It is a white powder, with an 

 odor similar to that of .chlorine gas. Its value depends 

 on the fact that the gas is thus brought into a solid 

 form, and made capable of transportation. It may be 

 released again by the simplest means, to be used as a 

 bleaching and disaffecting agent. The addition of an 

 acid, as has been seen in the chapter on chlorine, is all 

 that is necessary to effect this object. It occurs, in- 

 deed, spontaneously in the moistened powder, through 

 the action of the carbonic acid of the air. 



749. ILLUSTRATION. To illustrate its 



How may its 



properties be bleaching power, a strip of calico may be 

 illustrated? soa ked in a solution of the chloride, and 

 then in acid water. Nascent chlorine is thus liberated in 

 the fibre of the cloth, and is more effectual than if 

 otherwise applied. 



750. FORM OF COMBINATION. The che- 



How are its ... i -, 



elements com- mical action which occurs in the formation 

 lined? of chloride of lime is as follows. The 



chlorine combines with both constituents of the lime 

 forming with its metal chloride of calcium, and with its 

 oxygen, hypochlorous acid. This acid combines as it 

 is produced, with another portion of lime, forming a salt. 

 Bleaching powder is therefore a mixture of chloride of 

 calcium and hypochlorite of lime, with a certain pro- 

 portion of lime still uncombined. The name chloride 

 of lime has no chemical propriety. The mixture is, 

 practically, chlorine and lime, for as soon as an acid is 



