CHLORIDE OF LIME. 501 



M. E. Millon has quite recently announced some curious 

 discoveries respecting these compounds, which lead him to 

 take a new and simpler view of their constitution. When the 

 solution of chloride of lime is added to nitrate of lead, a white 

 precipitate falls, which after a time becomes brown. In the 

 first state it has hitherto been taken for chloride, and in the 

 second for peroxide of lead, but Millon finds that it is a com- 

 pound of protoxide of lead with chlorine, in both conditions, or 

 Pb -f O, Cl. With protonitrate of iron, a brown precipitate, of 

 similar constitution, Fe 2 + O 2> Cl is produced ; and with proto- 

 salts of manganese a similar precipitate, but containing twice as 

 much chlorine. In the case of each of these three nitrates, the 

 new compound corresponds with the peroxide of the same 

 metal, the protoxide acquiring chlorine instead of oxygen. The 

 red oxide, or suboxide of copper also, when warmed, absorbs 

 half an equivalent of chlorine, becoming 2 Cu + O, Cl, which 

 corresponds with the black oxide, the highest degree of oxida- 

 tion of that metal. Potash, he finds also, to absorb 2 equiva- 

 lents of chlorine, forming a compound K + O, 2C1, correspond- 

 ing with the peroxide of potassium, KO 3 ; while soda absorbs 

 only 1 eq. of chlorine, forming Na + O, Cl ; the peroxide of 

 sodium containing less oxygen than the peroxide of potas- 

 sium, although the composition of the former appears not to 

 be certainly determined. M. Millon concludes that the com- 

 pounds formed when chlorine is absorbed by metallic protox- 

 ides are bodies analogous to the peroxides of the same metals, 

 but in which the place of a portion of the oxygen is held by chlo- 

 rine. Bleaching powder is thus a compound of calcium with oxy- 

 gen and chlorine, in a hydrated condition, analogous to hydrated 

 peroxide of calcium, or hydrated peroxide of barium which is 

 better known. As a peroxide of hydrogen exists, the possibility 

 is inferred of an analogous compound of hydrogen with oxygen 

 and chlorine, H + O, Cl, which may be contained in the crystal- 

 line compound hitherto viewed as a hydrate of chlorine*. We 

 have already admitted similar substitutions of chlorine for oxy- 

 gen, as in chlorosulphuric acid (page 332). The relation between 

 a hydrated peroxide, such as that of barium, and chloride of li me 

 appears, in both being decomposed by acids, which unite with 

 the barytes and lime, and liberate oxygen from the one com- 

 pound and chlorine from the other. Peroxide of hydrogen also 



* Journal rle Pharmacie, Sept. 1839, page 595. 



