Dr. Beck on the Chlorides of Soda, Lime, fyc. 261 



be explained, and all the differences among chemists recon- 

 ciled, by the adoption of the principles heretofore advanced. 



The water contained in the hydrate of lime is essential to 

 the absorption of chlorine, and we have just seen that the 

 amount of chlorine absorbed depends upon the amount of 

 water. Thus, when the pure proto-hydrate is employed, no 

 more chlorine is absorbed, than would have been taken up 

 by the same amount of water, without the lime. Hence we 

 can account for that apparent partition of the elements of 

 the powder when more water is added ; and hence also the 

 reason why the powder, thus prepared, should have been con- 

 sidered as a sub chloride. But when to the proto-hydrate we 

 supply an additional quantity of water, more chlorine is ab- 

 sorbed, for the very reason that more water is present ; and the 

 residuum obtained in this case, when apparently dry, con- 

 tains a larger quantity of chlorine than in the former case, 

 when in fact it contains also a larger quantity of water. 



The fact stated by Dr. Ure, that the combination of chlo- 

 rine with the hydrate of lime follows no atomic proportion, 

 and the well known fact that different commercial samples 

 of the bleaching powder contain variable proportions of chlo- 

 rine, accord with the remarks just made. For with equal 

 care, the quantity of chlorine and consequently the efficiency 

 of the compound depends upon the quantity of water, either 

 combined or in contact with the lime. 



Thus it is evident, that there is a strict analogy in the phe- 

 nomena presented by the three supposed distinct compounds 

 which I have examined. In each, water is essential to the 

 absorption of chlorine ; in each, the amount of chlorine de- 

 pends upon the quantity of water ; and in each, by exposure 

 to air or to heat, the chlorine is evolved or gives rise to two 

 new acid compounds, which are definite and combine with 

 the bases forming muriates and chlorates. They are alike 

 possessed of the properties of bleaching and disinfecting, — 

 properties which are peculiar, and which belong also to a 

 simple solution of chlorine in water. Now it is conceived 

 more rational to refer these properties, in every case, to the 

 same cause, provided this cause is constantly present, than 

 to suppose that they belong to several distinct chemical com- 

 pounds, as of chlorine and soda, chlorine and the carbonate 

 of soda, chlorine and lime, &c. ; and particularly so when 

 with a single exception, (the oxide of chlorine,) the known 

 and acknowledged definite compounds of chlorine do not 

 possess these peculiarities. 



