ORES. 
dryness, in order to expel the excess of 
acid, and dissolved in water. The addi- 
tion of a solution of tin and muriatic acid 
will shew the presence of gold by a purple 
precipitate ; and platina will be indicated 
by a precipitate, on adding a solution of 
muriate of ammonia. When gold and pla- 
tina are both contained in the lame solu- 
tion, they may be separated from each 
other by the last mentioned solution, which 
throws down tlie platina, but not the gold. 
In this way platina may be detached also 
from other metals. 
For extracting “ silver” from its ores, 
the nitric acid is the most proper solvent. 
The silver may be precipitated from nitric 
acid by muriate of soda. Every hundred 
parts of the precipitate contains seventy- 
five of silver. But, as lead may be present 
in the solution, and this metal is also pre- 
cipitated by muriate of soda, it may be 
proper to immerse in the solution, a polish- 
ed plate of copper. This will precipitate 
the silver, if present, in a metallic torm. 
The muriate of silver is also soluble iu 
liquid ammonia, which that of lead is not. 
“ Copper ores” may be analyzed by boil- 
ing them with five times their weight of 
concentrated sulphuric acid, till a dry mass 
is obtained, from which water will extract 
the sulphate of copper. This salt is to be 
decomposed by a polished plate of iron, 
immersed in a dilute solution of it. The 
copper will be precipitated in a metallic 
state, and may be scraped oflf and weighed. 
If silver be suspected with copper, nitrons 
acid must be employed as the solvent; 
and a plate of polished copper will detect 
the silver. 
“ Iron ores” may be dissolved in dilute 
muriatic acid, or, if the metal be too highly 
oxydized to be dissolved by this acid, they 
must be previously mixed with one-eightli 
of their weight of powdered charcoal, and 
calcined in a crucible for an hour. The 
iron is thus rendered soluble. The solution 
must tlien be diluted with ten or twelve 
times its quantity of water, previously well 
boiled, to expel the air, and must be pre- 
served in a well-stopped glass bottle for 
six or eight days. The phosphate of iron 
will within that time be precipitated, if 
any be present, and the liquor must be 
decanted oft'. The solution may contain 
the oxides of iron, manganese, and zinc. 
It may be precipitated by carbonate of 
soda, which will separate them all. The 
oxide of zinc will be taken up by a solution 
of pure ammonia ; distilled vinegar will 
take up the manganese, and will leave tlie 
oxide of iron. From the weight of tliis, 
after ignition, during a quarter of an hour, 
twenty-eight per cent, may be deducted. 
“ Tin ores.” Boil 100 grains, in a silver 
vessel, with a solution of 600 grains of pure 
potash. Evaporate to dryness, and then 
ignite moderately for half an hour. Add 
boiling water, and if any portion remain 
undissolved, let it undergo a similar treat- 
ment. Saturate the alkaline solution with 
muriatic acid, which will tlirow down an 
oxide of tin. Let this be redissolved by an 
excess of muriatic acid : again precipitated 
by carbonate of soda ; and being dried and 
weighed, let it, after lixiviation, be once 
more dissolved in muriatic acid. The inso- 
luble part consists of silix. Into the colour- 
less solution, diluted with two or three 
parts of water, put a stick of zinc, round 
which tlie reduced tin will collect. Scrape 
oft' the deposit, wash, dry, and fuse it under 
a cover of tallow in a capsule placed on 
charcoal. A button of pure metallic tin 
will remain at the bottom, the weight of 
which, deducted from that of the ore, indi- 
cates the proportion of oxygen. The pre- 
sence of tin in an ore is indicated by a 
purple precipitate, on mixing its solution in 
muriatic acid with one of gold in nitro-mu- 
riatic acid. 
“ Lead ores” may be analyzed by solution 
in nitric acid, diluted with an equal weight 
of water. The sulphur, if any, will remain 
imdissolved. Let the solution be precipi- 
tated by carbonate of soda. If any silver 
be present, it will be taken up by pure 
liquid ammonia. Wash oflF the excess of 
ammonia by distilled water ; and add con- 
centrated sulphuric acid, applying heat, so 
that the muriatic acid may be wholly ex- 
pelled. 
“ Mercury” may be detected in ores that 
are supposed to contain it, by distillation in 
an earthen retort with half their weight of 
iron filings or lime. The mercury, if any 
be present, will rise and be condensed in 
the receiver. 
“ Ores of zinc” may be digested with 
the nitric acid, and the part that is dissolved 
boiled to dryness, again dissolved in the 
acid, and again evaporated. By this means 
the iron, if any be present, will be rendered 
insoluble in dilute nitric acid, which will 
take up the oxide of zinc. To this solu- 
tion add pure liquid ammonia, in excess, 
which will separate the lead and iron, if any 
should have been dissolved ; and the excess 
of alkali will retain the oxide of zinc. Thi.'. 
