~ 
382 Ht. Wurtz’ Contributions to Analytical Chemistry. 
tain some indications of decomposition. But on boiling for a 
long time freshly precipitated chlorid of silver with nitric acid 
of 1:29 sp. gr., renewing the acid frequently, not a trace of silver 
could be detected in the filtrate, and on evaporating acid of this 
strength repeatedly to dryness upon the same mass of the chlo- 
rid, the residue yielded to water no silver. A quantity of the 
chlorid (which had acquired a violet tinge by exposure to light) 
was then finely pulverized and boiled with acid of 1°48 sp. gr., 
with the addition of a little chlorohydric acid to provide against 
the possible presence of metallic silver or the subchlorid, for 
twelve hours. Under the influence of the acid the violet tinge 
very quickly disappeared, the mass becoming white. The mix- 
ture was then evaporated to perfect dryness upon the sand-bath, 
and water poured upon the residue. In the solution silver was 
now easily detected with chlorohydric acid, but on examination 
for nitric acid, not a trace could be found in the liquid. The silver 
acid having been derived from a minute trace existing in the 
nitric acid, which had distilled over with it during its rectifica- 
tion.* It may then be asserted that boiling nitric acid of 148 
sp. gr. is wholly without action upon chlorid of silver. We 
have here then a new and striking distinction between the two 
metals, lead and silver, which in many other respects appro 
each other in their chemical relations and reactions. 
23. Gold.—According to Pelleticr,+ ‘nitric acid, on accoun 
of its easy volatility, has no action upon terchlorid of gold. 
Pelletier’s fuct I find substantially confirmed by careful expert 
ments, but the explanation which he assigns may reasonably 
held in doubt. A solution of pure terchlorid of gold was evap 
orated at an extremely gentle heat (much below 100° C.) an the 
residue, which was crystallized in beautiful radiating _ 
nt 
’ 
treated with nitric acid of 1-48 sp. gr., in which it dissolv pace 
clear yellow liquid. This was evaporated, first on the sane 
bath, and when concentrated, at a temperature little above that 
* This nitric acid was prepared original by distilling saltpetre with oil of fe 
riol, the first. portions eenie rotted as ¢ ra i was re-distilled care 
t 
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strong nitric acid (Handbuch, i, 805), recommends that the acid which has 
ith HO, SO2 should be freed from the latter yi a distilla- 
tion, “either by itself or over saltpetre.” It is evident from the above t : 
tion by itself will not answer. Nitrate of baryta might be better t ae ae phurie 
and nitrate of silver probably still better, because it would retain both 
lori 
acid and the ch 
{ Gm. Handbuch, iii, 672. 
