196 
ON THE ACTION OF SAL AMMONIAC, ETC. 
If we expose the mixture to the air, it soon loses its white 
color ; at the end of 24 hours it commences to become yel- 
low, and this more rapidly in appearance, when spread in 
thin layers on filtering paper, or still better if placed in con- 
tact with organic substances. 
The solution of this mixture, which has been exposed to 
the air, is colored of an orange tint, and assumes with a solu- 
tion of search, an indigo blue ; there is, therefore free iodine 
present. 
When a colorless aqueous solution of the fresh mixture is 
exposed to the air, it becomes yellow and strikes a blue color 
with a solution of starch ; while u solution of the fresh mix- 
ture, kept in well stopped vessels, was preserved for months 
without change. 
If we place the fresh mixture in a porcelain capsule, over 
mercury, and cover it with a bellglass, filled with carbonic 
acid gas, no absorption or change takes place. 
The fresh mixture was finally placed under a bell glass of 
air dried by chloride of calcium ; it was preserved for many 
days without becoming yellow, while the same introduced in- 
to a moist air, lost its pulverulent form, and became con- 
glomerated into yellow balls, which became blue .with a solu- 
tion of starch. 
I placed the white mixture in a flat porcelain plate, in the 
cellar, and covered it with a cylinder, which had a number of 
small openings near the bottom to create a current of air ; up- 
on the open part of the cylinder was placed paper moistened 
with solution of starch. The paper separated from the surface of 
the mixture by a space of about three inches, became blue at 
the end of some days ; which did not take place when the 
vessel was covered with paper impregnated with fecula, and 
moist air excluded. 
The mixture in the cellar became partially liquid, and af- 
terwards passed to a dry state ; new pieces of paper steeped 
in a solution of starch, and placed at a certain distance from the 
mixture, assumed a blue tint for four months; from which it 
results, that iodine was disengaged for a longtime, so that this 
