26 Dr. Ure on Chlonde of Lime. 



parts of chlorine gas ; or 100 grains of the former should yield 

 81.8 grains of the latter, equivalent in volume to 107.28 cubic 

 inches. To afford this quantity of chlorine, two atoms of 

 muriatic acid must act on one atom of peroxide ; one atom of 

 hydrogen quits the muriatic acid, to unite with one atom of 

 oxygen in the oxide, forming an atom of water; the corre- 

 sponding atom of chlorine is disengaged ; while the resulting 

 atom of metallic protoxide attracts and neutralizes the second 

 atom of muriatic acid. Or in numbers 5.5 parts of peroxide 

 of manganese, take 4.625x2 = 9.250 of muriatic acid gas, 

 •which by the above table* are present in 100 grains of liquid 

 acid, specific gravity 1.045. Thus 10 grains peroxide of man- 

 ganese require 16.8 of muriatic acid gas, equivalent to 100 

 grains of liquid acid of 1.082. 



When a mixture of sulphuric acid, common salt, and black 

 oxide of manganese are the ingredients used, as by the manu- 

 facturer of bleaching powder, the absolute proportions are : 



1 atom muriate of soda . 7.5 29.70 100.0 



1 atom peroxide of manganese 5.5 21.78 73.3 



2atomsoilof vitriol 1.846 12.25 48.52 163.3 



25.25 100.00 



And the products ought to be ; 



Chlorine disengaged, . . 

 Sulphate of soda .... 

 Proto-sulphate of manganese 

 Water 



25.25 100.00 

 These proportions are, however, very different from those 

 employed by many, nay, I believe, by all manufacturers ; and 

 they ought to be so, on account of the impurity of their oxide 

 of manganese. Yet making allowance for this, I am afraid 

 that many of them commit great errors in the relative quan- 

 tities of their materials. Thus I have been informed by one re- 

 spectable manufacturer, that he employs 10 of salt, l2of sulphu- 



* See last Number of the Journal, p. 289. 



