MANGANESE. 223 
printers' ink. As a discharger of colour it is applied in 
small quantities, and, by the oxygen which it gives out, 
it is said completely to destroy any tinge left in the glass, 
by the presence of iron, and some other colouring mat- 
ters. This property has obtained for it the appellation 
of the soap of glass. 
It is from manganese that all the oxygen gas (21 ) 
used by chemists is obtained. By the application of a 
red heat this is yielded in such abundance that an ounce 
of the oxide of this metal will yield about two quarts of 
gas. The consumption of manganese has, of late years, 
become very considerable by the discovery of the 
oxygenated muriatic acid, which is now extensively 
used in the bleaching of linen and cotton ; that liquor 
being made by the distillation of the oxide of man- 
ganese with spirit of salt (muriatic acid, 29). 
