Mr. Detmer on Bleaching Salts. 4'2S 



ina chloride of calcium and hypochlorous acid. The hypo- 

 chlorous acid combines with the other atom of lime. 



Starting from the composition of chlorochromic and chloro- 

 sulphuric^acids, which are represented by Walter and Re- 

 gnault as chromic and sulphuric acids in which the third pro- 

 portion of oxygen is replaced by chlorine (Cr Og + CI and 

 S O2 + CI), Millon supposes that the bleaching chlorides have 

 a similar relation to the peroxides of their metals. The per- 

 oxide of calcium being Ca Oo, or Ca O + O, bleaching pow- 

 der is Ca O + CI, or the peroxide of calcium, with chlorine 

 substituted for its second proportion of oxygen. In support 

 of this view Millon adduces observations of his own on the 

 composition of the bleaching compounds of chlorine with dif- 

 ferent metallic oxides, such as oxides of lead and protoxide 

 of iron, as well as potash, soda and lime, in which the pro- 

 portion of chlorine was found to vary, but to correspond with 

 the excess of oxygen above one equivalent in the peroxides of 

 the same metals. In particular, potash was found to absorb 

 two equivalents of chlorine, and soda only one, the peroxide 

 of potassium being K O + 20, while the peroxide of sodium 



isNaO + O. • , , J- . J . 



The attention of the author was particularly directed to 

 ascertain the accuracy of the latter statement. A solution of 

 carbonate of soda was charged with chlorine gas till it acquired 

 a yellow colour and retained not a trace of carbonic acid. 

 The solution was then briskly agitated with air, by which the 

 excess of free chlorine escaped. In analyzing the solution 

 afterwards, one portion of it was treated with a few drops of 

 ammonia, and the chlorine afterwards precipitated by nitrate 

 of silver ; another portion was evaporated to dryness for the 

 sodium, which was obtained in the state of chloride of sodium. 

 In four experiments the liquids charged with chlorine con- 

 tained chlorine and sodium in the following proportions, m 



100 parts: — 



Sodium 4.7-88 45-26 46-81 44-76 



Chlorine 52-12 54-74 53-19 55-24, 



while, if the bleaching chloride of soda contained 1 eq. of 

 chlorine to 1 eq. of soda, its composition would be 



1 eq. sodium 4.6-9 1 



1 eq. chlorine .... 53-09 



100-00 



The results correspond as closely as could be expected 

 with this theoretical statement. There can be no doubt then 

 that the chloride of soda contains one of chlorine to one of 

 soda. This is the result required by Millon's theory, the 

 peroxide of sodium containing, according to him, one of oxy- 



