1^35.] Bleaching Powder. 



I shall state the analysis of 100 grs. of a very pure bleach- 

 ing powder, upon which the most numerous experiments 

 were made : — 



Matter insoluble in water 10'55 atoms. 



Chlorine 38-63= 8-5 or 1- 



Lime 30-05 = 8-5 „ 1- 



Water ...... 20-77 = 18-4 „ 2-16 



100-00 

 Now, the lime consisted of an atom of calcium united to 

 an atom of oxygen. We may, therefore, state the ultimate 

 constituents of bleaching powder as follows : — 



1 atom chlorine , . . 4*5 

 1 atom oxygen . . . 1- 



1 atom calcium . . . 2-5 



2 atoms water . . . 2-25 



10-25 



But the calcium united to the chlorous acid must have 

 been in the state of lime. And it is quite evident (if we 

 suppose the bleaching powder perfectly pure) that during 

 the process one half of the chlorine decomposes one half of 

 the lime^ converting it into chloride of calcium. The oxy- 

 gen thus disengaged unites to the other half of the chlorine, 

 converting it into chlorous acid ; and this acid combines 

 with the other half of the lime. Hence, bleaching powder 

 (when as strong as possible) is composed of, 



1 atom chloride of calcium . 7- 

 1 atom chlorite of lime . . 9- 

 4 atoms water 4-5 



20-5 

 The presence of the water is essential to the formation of 

 the salt. Hence, it is probable that it is in combination 

 with the chlorite of lime. 



3. When the bleaching powder is very weak -no chlorine 

 whatever passes over into the Wolfe's bottle. When the 

 powder was of the best quality the quantity which came 

 over was 7*3 grs. from 200 grs. of the bleaching powder. 



4. When the bleaching powder was old, the quantity of 

 oxygen extricated, compared with that of the chlorine, was 



