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SELECTED ARTICLES. 
trate of lead, there is thrown down a brown substance, having 
all the exterior properties of peroxide of iron, but which is 
represented by the formula Fe 2 2 Cl; it is again the peroxide 
in which all the oxygen constituting the higher degree of 
oxydizement is replaced by its equivalent of chlorine. With 
the protosalts of manganese an analogous precipitate is pro- 
duced, but the quantity of chlorine is doubled. If the persalts of 
iron and manganese be employed, instead of the protosalts, a 
subsalt is deposited, and chlorine is disengaged in abundance. 
With the salts of deutoxide of copper the phenomena take 
place differently. A compound is formed, and which decom- 
poses almost immediately at common temperatures, and liber- 
ates pure oxygen. At the same time that the oxygen is dis- 
engaged, an oxychloride of copper is deposited, of which the 
formula is Cu 2 OCl, and which thus corresponds to the deutox- 
ide. The same compound is formed directly, by passing dry 
chlorine upon protoxide of copper, slightly heated by the 
flame of an alcohol lamp." 
" It is very easy," says M. Millon, " to generalise these 
facts, and consider the bleaching compounds, formed by the 
alkalies, as compounds corresponding to the peroxides, but in 
which an equivalent amount of chlorine has been substituted 
for that portion of the oxygen which constitutes the peroxide. 
Then in these two orders of compounds, an analogy in com- 
position would lead to an analogy in properties; the same 
want of permanency, the same oxydizing power, the same de- 
colorising action, for the alkaline peroxides exhibit great en- 
ergy in bleaching. 
" This new theory should find its verification in the com- 
parative composition of the bleaching compounds of soda and 
potassa. The two peroxides of these bases have a very dif- 
ferent composition. That of potassium is KO 3 , that of sodium, 
which is not given by Thenard, but is represented in the 
tables of Berzeiius, by Na 2 3 . It results from these two for- 
mulas that the bleaching compound of potassa should contain 
four times as much chlorine as that of soda. 
KaO-fO 2 peroxide of potassium corresponds to KaO-f-Cl 2 . 
Na 2 2 +0 peroxide of sodium corresponds to Na 2 2 4-Cl. 
