COP ( 355 )
Copper
5441
Oxygen
* 3 -<> J
Water
# •
14.
Sulphuric Acid
18.
100.0
Sulphat of copper is of courfe decompofedby all the alkalies pure or carbonated. If afolution of blue vitriol is poured into liquidpotalh, or if the latter is added to the former tocompleat faturation, a blue precipitate falls down,which, when thoroughly wafhed with muchboiling water, gives that peculiar combinationfirft difcovered by Prouft, and called by himHydrat of Copper .
This i'ubftance when dried at a heat not abovethat of boiling water, has not exactly the confid-ence ©f a powder, but rather that of Pruffian blue.With a heat fomewhat higher it fhrinks andgradually becomes converted to the black oxyd.By dry diftillation it is found to lofe in its paf-fage to the date of black oxyd 24 per cent, ofits weight, which is nothing but water, andabout 1 of carbonic acid, which laft it appearsto abforb from the air in drying, and 75 partsof the black oxyd remain. If this laft is againmoiftened with water it does not return againto the ftate of hydrat, nor aflume any other butthe brownifh black colour of the pure oxyd.Hence it appears that the hydrat is a true che-mical combination of about 3 parts of oxyd ofcopper with one of water, and as Mr. Chenevixhas well obferved, enters as fuch into the cotn-pofition of the cupreous falts. Therefore ful-phat of copper (for example) might, with morepropriety be faid to be thus compofed.
Copper 25.61 forming COxygen 0,4 V Hydrat < 42.6Water 10.6 J of Copper
Sulphuric Acid . 32.0
Water of. Cryftallization 25.4
100.0
The hydrat- is ftill better formed from thenitrat by the addition of potalh, and alfo fromall the other cupreous falts. In all cafes itswater is feparated either by heat, or by boilingwith potalh.
Sulphat of copper is decompofed by doubleaffinity by many other falts. With commonfait, muriat of copper is formed, and this isfeen at once by the change of colour of thefolution from blue to green, Sulphat of copper
COP
and acetite of lead produce the acetite of copper,and this is a convenient method of preparingthis" fait as will be further mentioned.
Copper unites readily with carbonic acid,and this combination, like the former, is alfofound, largely in nature, the analyfis of whichhas already been noticed. Whenever copper isexpofed to a damp confined air it readily rufts,and the green cruft formed on its furface is alfoa carbonated oxyd. But the readieft way ofproducing the carbonats artificially, is by addinga carbonated alkali to the fulphat, nitrat, or anyother acid fait of copper. A very copious bulkygreen precipitate is collected, which, wellwafhed, and gently dried, forms a beautifulapple-green powder often ufed as a pigment invarious forms. A hundred parts of copperdilTolved in any acid, and precipitated by carbo-nated potafh or foda, produce invariably 180 ofthe green carbonat, dried at a boiling-waterheat. This carbonat diftilled without additionwith a heat gradually increafed to rednefs,gives out 10 parts of water, and 46 of carbonicacid, and at laft 125 parts of the black oxydremain in the retort, which quantity (as alreadymentioned) is precifely that which is left whenthe green carbonat is boiled with potafh, and istherefore alfo equal to 100 of metallic copper.To preferve the uniform green colour, for whichthe carbonat is valued, it fhould be repeatedlywafhed with boiling water, the heat appearingto increafe the denfity of the precipitate, andof courfe the body of colour. An excefs ofthe carbonated alkali redifiolves part of the car-bonated oxyd.
When the hydrat of copper is gently heatedwith a folution of carbonat of potafh fuperfatu-rated with carbonic acid, a part is dilTolved,forming a greenifh-blue liquor”, whilft the re-fidue remains at the bottom, of a colour ap-proaching to that of the black oxyd. Thefolution, llowly evaporated, yields a lingularfait, being a carbonat of potafh, holding no morethan 5 per cent pf oxyd of copper, and 43 ofcarbonic acid. It is flightly deliquefcent andcryftallizable. A fimilar fait, but with the ballsof foda, is formed, when carbonat of foda isufed.
Copper diffolves in nitric acid with extremeeafe, when moderately diluted, and even in thecold. Much heat is excited, and if the folutiongoes on vigoroully, a torrent of Nitrous Gas isgiven out (which indeed is one of the moft con-venient modes of procuring this gas) at the fametime that the folution becomes of. a deep blue.
“ Chenevix.