244 BEHAVIOUR OF CHARCOAL WITH CHLORINE, ETC. 
charcoal powder even at a temperature of 212°. If char- 
coal powder and liquid bromine are quickly triturated to- 
gether, but little bromine is lost ; most of it is absorbed by 
the charcoal, which d^es not part with any bromine at 212°, 
but only at a higher temperature. 7. An aqueous solution 
of bromine is wholly deprived of its bromine by charcoal 
powder. 8. Vapours of iodine are quickly absorbed by 
charcoal powder even at 212° ; when one part of iodine is 
triturated with nine parts of charcoal powder, this mixture 
does not disengage a trace of iodine even at 212°. This 
combination of iodine and charcoal turns guaiacum tincture 
blue, just as iodine. Brownish-yellow iodine water can be 
instantly and entirely decolorized by charcoal powder. 
9. Schonbein had previously shown that charcoal powder 
eliminates hyponitric acid from the first hydrate of nitric 
acid without any carbonic acid being formed. The author 
explains this according to his view of the constitution of 
nitric acid, assuming that the hydrate of nitric acid = NO'* 
H02 is separated into NO* and HO^ when the HO^ is de- 
composed without carbonic acid being produced. When a 
glass tube is filled with a mixture consisting of nine parts 
of water and one part hyponitric acid, a violent disengage- 
ment of nitric oxide results, but no carbonic acid is formed. 
Ihid, from Poggendorff^s Jinnalen, 
