1824.] -'■/. (jii(/-Lii.ssiu- un the CkloridAof.Linae. 219 



potash, or soda of commerce, has long been known in France 

 by the name of eau dejavelle.; that with lime was called oxy- 

 muriate of lime ; but it is more accurate to denominate the first, 

 as is now generally done, chloride of potash or soda, and the 

 latter chloride, of lime. 



The chlorides of potash, soda, and lime, have very little sta- 

 bility of composition ; the two hist, indeed, can only be obtained 

 in the liquid state, in a large quantity of water. If, for instance, 

 we pass chlorine into a concentrated solution of potash, at first 

 chloride of potash will be formed ; but this chloride will soon be 

 decomposed, and converted into chlorate of potash, and chloride 

 of potassium. The two latter compounds, not having the pro- 

 perty of destroying colours, must be avoided, and the only 

 means of preventing their formation is to employ- a verv weak 

 solution of the alcali, which, at most, should not exceed the 

 proportion of 125 grammes to a litre of water. (In round num- 

 bers, about 4-V oz. potash to 2^ pints of water.) 



Lime has not, like potash and soda, the inconvenience of con- 

 verting the chlorine into chloric acid ; it may consequently be 

 combined with the chlorine en masse. 



Lime, if perfectly dry, does not absorb chlorine, but it com- 

 bines with it rapidly when in the state of hydrate, that is, after 

 it has imbibed a sufficient quantity of water from a moist at- 

 mosphere, to split and fall to powder. Supposing it to be in 

 the state of hydrate, it forms, according to M. Welter, a sub- 

 chloride only, which is composed of 



2 proportions of lime = 2 x 35*603 = 71-206 

 2 water =2x 11-2435 = 22-487 



1 chlorine = 44-2653 



137-9583 



When mixed with water it is immediately decomposed; one 

 half of the lime is precipitated, and the other half remains in 

 solution, combined with the whole of the chlorine, and conse- 

 quently forming a neutral chloride. Hence there are two com- 

 binations of chlorine with lime, a sub-chloride, and a neutral 

 chloride. The sub-chloride is obtained by saturating hydrate 

 of lime with chlorine, and the neutral chloride by dissolving 

 the sub-chloride in water, or by saturating lime, dispersed 

 through water, with chlorine. 



The neutral chloride, or more simply the chloride, is very 

 soluble; it. may, however, be made to crystallize in small prisms. 

 Ik solution, left in contact with the air, is gradually decom- 

 posed, one part of the lime combines with the carbonic acid of 

 the atmosphere, whilst its chlorine is disengaged. This de- 

 composition of the chloride is retarded by constantly keeping 

 an excess of lime in the solution. From these properties of the 



