148 Academy of Sciences, Paris. 
the oxygenized muriatic acid, cause the oxide of gold to assume 
sat first a purple hue; but instead of assuming afterwards the ap- 
pearance of gold that has been precipitated by sulphate ‘of iron, 
it becomes dark-brown. These experiments have a tendency to 
prove the existence of a purple oxide of this metal. 
*“V. If oxygenized nitric acid be poured on oxide of silver, 
a strong effervescence ensues, occasioned, as in the preceding 
_cases, by a liberation of oxygen. One portion of the oxideis dis- 
solved. The other is first reduced, and afterwards is dissolved, 
if a sufficiency of acid be present. If potash be gradually added 
to the solution, when completed, a fresh effervescence follows, and 
a dark violet-coloured precipitate is thrown down (such, at least, 
is always the colour of the first deposit), which is insoluble in 
ammonia, and, to all appearance, a protoxide of silver, similar to 
‘what was observed by an English chemist while examining the 
action of ammonia on the oxide of silver. 
“VI. Oxygenized sulphuric and phosphoric acids likewise 
reduce partially the oxide of silver, with a strong effervescence, 
“VII. Having already noticed that the oxide ofsilver and oxy- 
genized muriatic acid, by their mutual action, produce’ water, 
disengaging oxygen gas and chloride of silver, | now remark that 
this chloride is of a violet colour : but violet chloride, however 
obtained, always leaves a metallic residue when treated with-am- 
monia. This phenomenon was observed by M. Gay-Lussac, re- 
specting white chloride turned to violet by the action of light. 
From thisit follows, that when oxygenized muriatic acid is treated 
with oxide of silver, a small portion of the liberated oxygen is 
furnished by the oxide itself : therefore, to determine by the pro- 
cess pointed out in my last paper, by means of this oxide, the 
quantity of oxygen in muriatic acid, we must take into the ac- 
count the oxygen furnished by the oxide: in order to which a se- 
cond experiment must be made, in which the chloride of silver, 
produced and mixed with oxide of silver; must be collected. This 
mixture being treated with ammonia gives, as a residuum, the por- 
tion of the metal that had been reduced ; the quantity of which 
informs us respecting the quantity of oxygen we are in quest of.-— 
With respect to the chloride of silver, it probably corresponds 
with the protoxide of silver. 
“VIII, When a tube containing oxide of silver is dipped into 
a solution of oxygenized nitrate of potash, a violent effervescence 
ensues ; the oxide is reduced, the silver is precipitated, all the 
oxygen of the oxygenized nitrate is liberated along with that of 
the oxide; and the solution, containing merely common nitrate 
of potash, remains neutral, if it was in that state at first. 
*“©1X. Oxide of silver produces the same effects on oxygenized 
muriate of potash as on the oxygenized nitrate. 
*¢ X. When 
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