CHEMISTRY. 
tion is not lefs effectual on the fluids; it pafles quickly 
through the firft paffa°-es, and combines with the blood, 
to which it gives denfity, confiftence, and colour, render¬ 
ing it more concrefcible, communicating at the fame time 
fuch a degree of activity as enables it to pals eafily into 
the fmalleft vefiels} which it ftimulates at the fune time, 
and communicates force and life through every part. 
The capital experiments of Menghini, publifhed in the 
Memoirs of the Inftitution of Boulogne, have proved, 
that the blood of perfons, who take martial medicines, 
is highly coloured, and contains a larger quantity of iron 
than it would naturally contain. Lorry, who exercifes 
the art of medicine with that accuracy of obfervation 
which chara&erises the true philofopher .and phyfician, 
obferved,- the urine of a patient to whom he had given 
iron, in a very divided ftate, became munifeftly coloured 
with nut-gall. This metal is therefore tonic, fortifying, 
ifcotnachic, diuretic, alterative, incifive, and unites in its 
action the properties of a great number of other medi- 
dicines. Like aftringents it increafes the motion of the 
parts, and has the advantage of being more conftant and 
durable in its effedts than many other remedies which 
poflefs the fame virtue, becaufe it combines with the or¬ 
gans tliemfelves, by means of the fluids which ferve for 
their nutrition. It feems, therefore, that in every cafe 
wherein the fibres of the vifcera, of the m.ufcles, or even 
of the nerves, have only a very feeble adtion, in languors 
of the ftomach, and fluggiflinefs of the inteftines, and in 
weaknefles produced by thefe caufes ; in fine, in all the 
cafes wherein the fluids are not fuiiiciently confident, or 
too much diluted, as in palfies and propenlities to the 
dropfy, &c. iron may be adminiftered with iuccefs. It is 
tiled under many different forms, Inch as the levigated 
filings, martial FEthiops, aftringent and aperitive faffron 
of Mars, martial alkaline tincture of Stahl, the martial 
flowers of fal-ammoniac, See. The fulphat of iron is ex¬ 
ternally ufed ia hemorrhages, &c. Iron, which poflefles 
the magnetic property, or the artificial magnet, his been 
reckoned among thole bodies which produce very Angu¬ 
lar effedts upon the animal economy. When applied to 
the Ikin, according to feveral modern authors, it miti¬ 
gates pain, diminilhes convulfions, excites redaefs, fweat, 
and often a linall eruption : it is likewife capable of ren¬ 
dering epileptic attacks lels frequent. It has even been 
affirmed, that, when left in water for twelve hours, it 
communicates a purgative property to that fluid. All 
thefe affertions, which are faid to be founded on fadls, 
iufficiently announce to enlightened phiiofophers the 
great difficulty which attends phyfical rematches into the 
animal lyltem. 
Of COPPER. 
Copper is a metal of a red brilliant colour, to which 
chemifts have given the name of Venus, on account of 
the facility with which it unites to, and becomes ctianged 
by, a great number of bodies. It has a difagreeable 
fmell, which is more fenhble tfhen it is rubbed of heat¬ 
ed ; its tafle is ftyptic and naufeous, though lefs percep¬ 
tible than that of iron; it is hard, very elaltic, fonorous, 
dudtile, and capable of being reduced into exceedingly 
thin leaves, or fine wire; by immerfion in water it lodes 
between one-eighth and one-ninth of its weight; its te¬ 
nacity is luch, that a copper wire of the tenth of an inch 
in diameter, can fuftain a weight of 299 pounds one quar¬ 
ter before it breaks; its fra&ure appears compofed of fmall 
grains ; it is fufceptible of a regular form ; the abbe Mon- 
gez deferibes its cryftals as quadrangular pyramids, fome-. 
times folid, and fometimes compofed of other fimilar fmall 
pyramids, laterally adhering. 
Copper, when heated, becomes coloured on its furface, 
nearly in the fame manner as fteel; the colours are blue, 
yellow, and, laftly, violet: when completely fufed tliele 
colours pafs off, and it appears covered with a-green 
flame, boils, and is volatilized, as may be obferved, in 
the chimneys of founderies. If this metal be projedted 
Vol. IV. No. 198, 
3°5 
through flame, in fmall filings, it produces a blue and 
green colour, and from that property it is ufed in fire¬ 
works. If the melted metal be luffered to cool flowly, 
and, after the furface is become congealed, the fluid por¬ 
tion be poured off, the remaining lolid part is found to 
be cryftallized in pyramids; which are more regular and 
large, in proportion as the fufion has been more complete, 
and the cooling more gradual; its pyramids are quadran¬ 
gular, and appear to be formed of a great number of oc¬ 
tahedrons, inferted one in the other. 
Copper heated with accefs of air, burns at its furface, 
and is converted into an oxyd of a dark red, in propor¬ 
tion as it abforbs the bale of vital air : this oxyd may be 
eafily obtained by heating a ball of copper to redneis, 
which caufes the oxyd to fcale off. The lame effedt takes, 
place when red-hot copper is quenched in cold water; 
the fudden contraction of the parts of the metal, facili¬ 
tating tne feparation'of the portion of oxyd which covers 
the furface: this oxyd falls to the bottom of the water, 
and is called feales of copper. As it is not perfectly oxy- 
dated, it may be burned afrefli in the muffel of the cu¬ 
pelling furnace ; after which lalt procels it is found to be 
of a deep brown colour. 
The air attacks copper with greater or lefs facility, ac¬ 
cordingly as the fluid is more or lefs loaded with moifture, 
and converts it into a ruff, or green oxyd, called verde - 
gris, which appears to have laline qualities, viz. tafte, 
and folubility in water. From this circumftance the an¬ 
cient chemifts admitted the exiftence of fait of copper. 
It is remarkable, that this ruft never attacks copper, ex¬ 
cept at the furface, and feems even to contribute to the 
prefervation of the internal parts and mafles of this me¬ 
tal, as may be feen in antique medals and ftatues, which' 
are preferved very well beneath a covering of ruft. The 
antiquarians call this cruft patina, and let a high value 
on it, becaufe it ftiews the antiquity of the pieces, which 
are covered with it. Many artifts, and in particular the 
Italians, know how to imitate this coating, and to coun¬ 
terfeit the antique bronzes. The oxydation of copper 
by humid air, -appears to be produced by water in the 
ftate of extreme divifion ; this fluid, however, does not 
appear to attack copper,.nor decornpofe it like iron, at a 
high temperature. This metal feems to be more oxycli- 
fiable by cold water; it being a well-known fadf, that 
more danger attends the fuffering of fluids to cool in 
copper veffels, than in making them boil; becaufe, as 
long as the fluid is boiling, and the veflel hot, the aque¬ 
ous vapour does not adhere to its furface ; but when the 
veflel is cold, the drops of water which adhere to its fides 
feem to reduce it into green oxyd. It is to the air and 
the carbonic acid diftributed therein we mufl attribute 
this oxydation ; for, by diftilling this ruft of copper in the 
pneumatic apparatus, Fourcroy obtained carbonic acid. 
Chaptal has a memoir on a new mode of manufadhir- 
ing verdegris. This procefs, pradbifed at Montpellier for 
fome years paft, confifts in caufing the refidue of grapes 
to ferment, and of putting it in layers between plates of 
copper, to develop the metallic oxyd, called verdegris. 
This method .is luperior to the old one, as it is much 
eafier, and attended with lefs. expence, becaule it requires 
no wine. Experiments of the fame chemilt prove alfo 
that white lead may be made in the lame manner. 
To reduce the oxyd of copper: mix feales, or. any 
other oxyd of copper, with foft or black l'oap ; make it 
into a ftiff pafte, and a little muriat of foda may be add¬ 
ed. Put the mixture into a crucible, and place it in a 
melting furnace ; heat it gently at firft, till the loap 
burns no longer; then increafe the fire rapidly, to give 
a white heat. Let the crucible cool, break it, and the 
button of copper will be found. 
To produce phoi'phorated copper: mix equal parts of 
thin pieces of copper and pholphoric glafs; add one- 
eighth part of powder of charcoal; meif the whole in a 
Heffian crucible. The refuit is a metallic button, whitiffi 
to the eye, but fometimes exhibiting rainbow colours. 
4 I This 
