C HEMISTRY. 
3°6 
This phofphure of copper detonates with nitre, and pro¬ 
duces, beiides the oxyd of copper, a phofphat of potafh. 
Expofed to the air, it lofes its brightnefs, and becomes 
black. 
Copper unites very readily with fulphur; the com¬ 
bination may be made in the humid way, that is to fay, 
by mixing- flowers of lulphur and copper filings together, 
with a fmall quantity of water; but it fucceeds much 
better in the dry way. A .mixture of equal parts of ful¬ 
phur in powder and copper filings, are put into a cruci¬ 
ble, which is heated by degrees till it becomes red-hot; 
the refult is a tmafs of a blackifh grey, a fort of mat of 
copper, which is brittle and mote fufible than the copper 
itf'elf. This compound is prepared for dying and paint¬ 
ing on callicoes, by placing ftrataof plates of copper and 
fulphur in powder in a crucible, and heating it gradu¬ 
ally. The kind of mat which is produced, is pulverized, 
and called <zs ‘veneris , which mult not be confounded 
with another preparation bearing the fame name, and 
formed of copper and muriat of ammoniac. 
Copper forms alloys with many metals. Melt in a 
crucible fix parts of copper with four of arfenic and four 
of potafli: it forms a metallic button white and brittle. 
If the experiment be made with arfeniat of potafli, in the 
proportion of eight parts of the fait to fix of the copper, 
the copper 'oles its colour entirely; it is called ‘white 
tombac. It may be carried to fuch a degree of whitenefs 
as to vie with ■filver, if three or four parts of this copper 
already whitened, be mixed with one part of arfeniat of 
potafh. 
Cronftedt fucceeded in uniting copper with nickel in 
different proportions ; but the prefence of the copper 
was always vifible, becaufe it always coloured the glafs 
of borax of a green and of a brown red. By melting to¬ 
gether fix parts of red copper and nine of bifmuth, it 
forms, according to Gellert, an alloy of a reddifh white, 
with cubic facets. It unites very readily with antimony, 
and affords a cupreous regulus, which is diflinguifhed by 
a beautiful violet colour ; it likewife decompofes ful- 
phure of antimony, and unites with the fulphur which 
it takes from the antimony. 
Copper unites difficultly with mercury; though a fort 
of amalgam may be produced, by triturating copper in 
very thin leaves with mercury. A plate of this metal 
plunged in a folution of mercury by an acid, becomes 
eoated over with a beautiful colour of filver, owing to 
the mercury which has been reduced and precipitated 
by the copper, and which has a greater affinity with oxy¬ 
gen than mercury has. It alio combines readily with 
zink. This combination may be made in two ways. 
Firft by fufion; a metal is produced whofe colour re- 
fembles that of gold, and which is much lefs fufceptible 
of ruff than copper, though lefs duftile than that metal: 
the nearer its colour approaches to that of gold, the more 
brittle it is; and it varies greatly according to the pro¬ 
portion of the mixture, and the precautions ufed in melt¬ 
ing it; its varieties are, fimilor, pinchbeck, princes-me- 
tal, yellow tombac, and Manheim gold. Secondly, by 
cementing plates of copper with native oxyd of zink, or 
lapis calaminaris reduced to powder, and mixed with 
charcoal; in a red heat, the copper unites with the zink, 
and forms brafs: this is lefs fufceptible of ruff than cop¬ 
per, and is likewife more fufible, and lefs malleable. But 
a ftrong heat, continued for a fhort time, deprives it of 
the zink with which it was united, and converts it into 
copper again. The following is Vauquelin’s analyfis of 
brafs: Diffolve a known quantity of brafs in the necef- 
fary proportion of nitric acid; put the folution into a 
bottle, and pour in a folution of cauftic potafh, till the 
excels is manifeff to the tafte; {hake it up immediately; 
then filter the whole; the zink diffolved in the potafh 
pafies through the paper, and the oxyd of copper remains. 
Wafh the metal till the laft portions of water have no 
tafte; dry the oxyd Of copper with a gentle heat; then 
V»eighit} and, fubtradting 0-35 from the amotint of the 
oxyd, you have the weight of the metal, for one hundred 
parts of oxyd of copper contain in that ftate thirty.five 
parts of oxygen. 
Melt in a crucible twelve parts of red copper and three 
parts of zink ; cover the mixture with charcoal-duff, to 
prevent the oxydation of the zink : this will produce a 
tombac of a fine gold colour. Melt one part of yellow 
copper and two parts of red copper; and you have a 
very dudlile metal of a beautiful gold colour. By add¬ 
ing oxyd of arfenic, you have a metal almoft white, brit¬ 
tle} of a very fine clofe grain : the proportions are, fix 
parts of red copper, four of zink, five of oxyd of arfenic, 
and the fame quantity of potafli. 
Tin combined with copper renders it fliflfer, harder, 
more brittle, and fpecifically heavier, than the two me¬ 
tals employed. This alloy is whiter, more brittle,, and 
more fonorous, in proportion as the quantity of tin is 
greater. When it is very white, it is called bell-metal \ 
when it contains a large proportion of copper, it is yel¬ 
low, and is called bronze. This laft is ufed in calling 
ftatues, and forming pieces of artillery, which require to 
be fufficiently folid not to burft, and not fo duffile'as to 
have their form deftroyed by the ftroke of bullets. The 
alloy or mixture is made in different proportions, add¬ 
ing, according to the ufes for which the metal is del- 
tined, either zink, or antimony, or both. Eight parts of 
copper and one of tin, form a yellowifli white metal with 
not much du&ility. Sixteen parts of red copper to one 
of tin, produce a metal more dudtile than the foregoing, 
with a colour approaching nearer to red copper. Eight 
parts of red copper and two of tin, form a metal very 
brittle and fragile, with a clofe fine grain, the colour of 
the copper being confiderably changed. 
There are feveral procefies for analyzing bell-metal in 
the works of Fourcroy, Pelletier, and La Grange. 1. By 
nitric acid, which feparates the copper. 2. By adding 
oxyd of manganefe to oxydate the tin. 3. By calcining 
a portion of the metal. 4. By throwing fifteen parts of 
oxyd of copper into one hundred of bell-metal in fufion: 
the tin fepayates the oxygen, and riles oxydated to the 
furface; take this away; then the oxydated copper be¬ 
comes reduced, and mixed with the other. 
Tinning of copper confifts in applying a plate or layer 
of tin to the furface of the metal, and making it adhere. 
There are feveral ways of preparing the copper to re¬ 
ceive the tin. Some ferape the copper, to render the 
furface clean and brilliant; others rub it with wine- 
lees, a little very weak nitric acid, and land. Then there 
are two modes of applying the tin : 1. Melt the tin, co¬ 
vering the furface with powdered refin, and plunge in the 
pieces intended to be tinned ; but the copper, that it 
may take the tin better, is generally dipped previoufly in 
a folution of muriat of ammoniac, but it mtift be dried 
before it is plunged into the melted tin. This mode is 
when pieces of copper are to be tinned on both fides. 
2. For tinning copper vefiels on the infide only, heat the 
velfel over charcoal; put in the infide a quantity of tin, 
let it melt; put in a little muriat of ammoniac in pow¬ 
der, and rub it in with a handful of tow ; fpread about the 
melted tin in the fame manner in all the places impreg¬ 
nated with the fait. The intent of the muriat of ammo- - 
niac is to cleanfe the furface of the copper, and to pre¬ 
vent the oxydation of the tin. It is with jultice com¬ 
plained, that the tinning of copper vefiels is not fuffi- 
cient to defend them from the adtion of air, moilture, 
and {aline fubftances, becaufe thefe vefiels hre frequently 
obferv^d to be covered with verdegris. It might be pof- 
fible to remedy this inconvenience by a thick covering 
of tin, if there were riot realon to fear, that a degree of 
heat luperior to that of boiling water, to which thefe 
vefiels are often expofed, would melt the tin, and leave 
the furface of the copper uncovered. To prevent this 
laft accident, the tin may be alloyed with iron, filver, or 
platina, to diminifti its fufibility, and render it capable 
of being applied in thicker ftrata on the copper. Alloys 
