CHEMISTRY. 
3°8 
purpofe, put a certain quantity on a ffone or in a large 
mortar, and add a little quicklime in powder; the mix¬ 
ture, by trituration, affumes immediately a bright blue 
colour: the quantity of lime fhould be feven or ten parts 
to ioo of the precipitate. If the precipitate be too dry, 
add a very little water, to give the mixture a proper con- 
fiftence for trituration. Then dry the whole. This is 
totally foluble in acids with effervefcence, and carbonic 
acid gas is difengaged, which proves that a great quanr 
tity is abforbed in its formation. Pelletier, to whom we 
are indebted for this procefs, regards blue ajhes as a com¬ 
bination of carbonat of lime and carbonat of copper. 
The nitrat of copper exhibits the fame phenomena as 
the fulphat, when combined with alkalis; but in general 
the precipitates are of a. finer blue. Ammoniac re-dif- 
folves the precipitate, and produces a triple fait, nitro- 
ammoniaco of copper. Tire hydro-fulpliures and Pruf- 
fiats produce the fame effebrs as with the fulphat of cop¬ 
per. The fulphuric acid likewife diffolves nitrat of cop¬ 
per, and blue cryftals of fulphat of copper are obtained, 
if the acid be ufed in a very concentrated Itate. Iron 
has a ftronger affinity with mo.it acids than copper. When 
a plate of iron is plunged in a folution of copper by acids, 
and in particular by the nitric acid, the copper is preci¬ 
pitated in the metallic form, and covers the furface of 
the iron ; this precipitation depends on the ftronger affi¬ 
nity of the iron than of the copper to oxygen. The ful¬ 
phat of copper exhibits the fame phenomenon, and this 
procefs has been ufed by impoftors to make the credulous 
believe they were able to convert iron into copper. 
The muriatic* acid does not difl’olve copper, unlefs it 
be concentrated and boiling. Only a finall quantity of 
hydrogen gas is difengaged during this folution. The 
combination forms a magma very foluble in water; if it 
be lixiviated, the water becomes of a beautiful green co¬ 
lour, which diftinguifhes this folution from the two fore¬ 
going ; when flowly and cautioufly evaporated, and fuf- 
fered to cool, it depofits prifmatic cryftals of a regular 
form; on the contrary, if the evaporation has been too 
rapid, and the cooling too fudden, it prefents only very 
finall (harp needles. The muriat of copper is of a very 
agreeable gral's green colour, its taile is caultic, and very 
aftringent, and it melts by a gentle beat, congealing 
again into a inafs when fullered to cool. It ftrongly at- 
. tradls the moifture of the air, and is decompofable by 
the fame intermediums as the preceding lalts of copper. 
The fulphuric and nitric acids do not decompofe this 
muriat. The nitric foliations of mercury and filver de¬ 
compofe it by double affinity, a white precipitate being 
formed by the tranfpofition of the muriatic acid to the 
oxyd of mercury or of the filver, and by the union of 
the oxyd of copper to the nitric acid. Evaporated to 
drynefs, it aflumes a brown colour; and, if the experi¬ 
ment is made in clofe veffels, oxygenated muriatic acid 
may be obtained ; which proves that the copper in this 
ftate contains lefs oxygen. 
Arfenical acid hasfome adtion with the oxyd of copper, 
but none on the metal itfelf. Fluoric acid diffolves cop¬ 
per, and ftiil more readily its oxyd. The blue gelatinous 
folution which it forms affords cryftals of a blue colour, 
and cubical ihape. Boracic acid has little adtion diredtly 
on copper in the moift way ; but, if a folution of borax 
be added to a folution of fulphat of copper, a pale.green 
coloured fait is precipitated, which is difficultly foluble 
in water, but which, in the fire, melts into a grecnifh 
glafs. Phoiphoric acid diffolves only a fmall portion of 
copper, but it adts more powerfully on the oxyd. The 
folution affords, by evaporation, a green tranfparent 
gum-like mafs, which meks into a dark opake glafs in 
the fire. The affinity of thefe acids for copper is ftiil 
very undetermined. Copper will not combine with car¬ 
bonic acid but in the oxyd ftate : this combination is 
called carbonat of copper, or malachite. This carbonat 
may be decompofed by heat in the pneumatic apparatus: 
carbonic acid gas paffes over, and a brown oxyd of cop¬ 
per remains in the . retort, if the heat has been ftrong 
enough towards the end. Mod of thefe falts are foluble 
in alcohol, efpecially the nitrat and muriat of copper. 
The alcohol then burns with a green flame. 
Copper decompoles muriat of ammoniac very readily. 
Bucquet who examined this decompofition with great 
care, obtained by the pneumatic apparatus over mercury, 
from two drachms of copper filings, and one drachm of 
ammoniacal muriat, fifty-eight inches of elaftic fluid, 
of which twenty-fix inches confilted of very pure am¬ 
moniac gas, twenty-fix of detonating inflammable gas, 
and fix of mephitical gas, which extinguifhest candles, 
without being abforbed with water, and without preci¬ 
pitating lime water. A fmall quantity of liquid ammo¬ 
niac is difengaged, which fwims over the mercury. When 
this decompofition was repeated in the dofe of four ounces 
of copper with two ounces of ammoniacal muriat, in 
the common apparatus, Bucquet obtained two drachms 
eighteen grains of blue liquid ammoniac, which effer- 
yefeed a little with acids, and contained about one cubic 
inch of carbonic acid in the drachm. Fourcroy repeat¬ 
ed this experiment, with ammoniacal muriat purified by 
fublimation, and obtained a very caufticammoniac, which 
did not at all effervefee with acids. The oxyd of copper 
likewife decompofes ammoniacal muriat, and affords a 
portion of carbonat acid, together with the ammoniac 
it difengages, which renders the latter effervefeent. This 
alkali is always blue, becaufe it carries up with it a fmall 
portion of the oxyd of copper, to which its colour is 
owing. Acids do not however precipitate this metal. 
Two medicines are prepared in pharmacy with ammoni¬ 
acal muriat and copper, of which the firft has received 
the name of cupreous ammoniacal flo-jcers, or ens veneris,. 
and is nothing more than ammoniacal muriat coloured 
by a fmall portion of oxyd of copper. A mixture of 
eight ounces of this fait, with one drachm of the oxyd 
ot copper, is fublimed in two earthen veffels, theone 
placed on the other: all the ammoniacal muriat is vola¬ 
tilized without being decompofed, and carries up a finall 
quantity of oxyd of copper, which gives it a bluiffi co¬ 
lour. The fecond, which is called aqua celejlis, is pre¬ 
pared by fullering a pound of lime-water, and an ounce 
of ammoniacal muriat, to remain in a copper vefiel with¬ 
out heat for ten or twelve hours; the lime difengages the 
ammoniac, which diffolves a fmall quantity of copper of 
the bafon, and produces the blue colour. The celeftiai 
water may be made in a glafs or earthen vefiel, if a finall 
quantity of filings, or oxyd of copper, be added to ther 
lime-water and ammoniacal muriat. In either cafe, the 
liquor is' to be filtered ; and it may be oblerved, that 
in this experiment calcareous muriat and ammoniacal 
cupreat are formed. From the cupreatmay be obtained 
cryftals by evaporation. It does not fulminate, like the 
orat of ammoniac; but it is as foluble. By diftillation, 
water, azotic gas, and oxyd of copper, are obtained. 
Copper appears to decompofe fulphat of alumine ; for 
if a folution of this fait be boiled in a copper vefiel, a 
fmall quantity of alumine is depofited; and, when the 
alumine is precipitated by ammoniac, its earth affumes 
a flight blue colour, denoting the prefence of copper. 
This effedt may likewife be attributed to the finall excels 
of acid which fulphat of alumine always contains. 
The ufes of copper are numerous, and well known. 
The alloy of copper and zink is moil commonly prefer¬ 
red, on account of its great dudtili.y and its beauty. As 
copper is a very violent poifon, it ought never to be adrai- 
niltered in medicine. The properelt remedies in cafe of' 
poifonlng by copper reduced into oxyd or verdegris, are 
emetics, abundance of water, alkaline fulphures, alka¬ 
lis, &c. 
Of SILVER. 
Silver called Luna or Diana by the alchemiffs, is of a 
white coiour, and of the molt lively brilliancy; it has 
neither talte nor fmell; its Ipecific gravity is fuch, that it 
lofes 
