C H £ M I 
neral wliofe nature and rank among„other minerals had 
long embarrafled philofophers, is nothing more than a 
natural combination of a large proportion of charcoal 
with a very fmall quantity of iron. Plumbago was a long 
time confounded with molybdena. Both, without dil- 
tinftion, were called lead ore, Englifk crayon, flomb de 
mer, black cerufe, mica of the painters , crayon of lead, falfe 
galena, talc, blende, potelot, See. The native carbure of 
iron, a name fubftituted for that of plumbago, as being 
more expreffive of the nature of the compound, is found 
in mountains, often between beds of quartz, felt fpar, 
clay, or calcareous earth, in the form of roundifh irre¬ 
gular pieces, of different magnitudes; the largeft of which 
weigh from eight to ten or eleven pounds; it is likewife 
found diffemmated in much fmaller fragments, and, 
Sometimes even in beds or llrata. La Peyroufe reckons 
carbure of iron among the minerals of the Pyrenean 
mountains. It is likewife found in Spain and Germany, 
and alfo in the county of Cumberland in England, where 
it is made into pencils, which are highly efteemed. 
North America, and the Cape of Good Hope, likewife 
afford lotne fpecimens. Within thefe few years, plum¬ 
bago, cryftallized in oftahedrqns, has been difeovered. 
Iron has a great affinity, or elective attraftion, for ful- 
phur ; hence this metal decompofes almoft all the metal¬ 
lic fulphures. To make fulphure of iron, take two parts 
of iron-filings, with one part of fulphur; mix, and melt 
them together in a crucible. Vauquelin conceives this 
metal to be only an hydro-fulphure, becaufe, by pour¬ 
ing an acid into the mixture, a great quantity of fulphu- 
rated hydrogen is difengaged. Or, this artificial fulphure 
may be made, by applying a fmall bar of iron, heated to 
whitenefs, to a roll of fulphur ; they both melt. This 
fliould be done over a vefTel of water, that the portion of 
fulphur not combined with the iron may be immediately 
extinguifhed. The combination in the water is found to 
confiit of blackiffi brittle globules, fimilar to pyrites, and, 
like them, formed of fmall (lender pyramids, converging 
to a centre. 
Another way: A mixture of iron filings and fulphur 
in powder, moiftened with a fmall quantity of water, 
becomes hot in a few hours, at which time it fwells up, 
its parts adhere together, it abforks the water, breaks 
with a perceptible noife or crackling, and emits aqueous 
vapours, attended with a very manifefc odour, refem- 
biing that of fulphurated hydrogen gas. 
All the pyrites, or native fulphure of iron, are eafily 
decovnpofed. A fmall degree of heat is fufficient to de¬ 
prive them of their fulphur. Expofed to the air, theful-' 
phure of iron undergoes achange, efpecially when damp ; 
it fwells, cracks, lofes its biightnefs, and is covered 
with an efflcrefcence of a greenifh white colour, which 
is nothing but fulphat of iron. By melting the fulphure 
of irony and fprinkling it with muriatic acid, fulphura¬ 
ted hydrogen gas may be obtained by means of the pneu¬ 
matic apparatus. 
Iron combined with arfenic, affords a brittle alloy, 
very little known. With cobalt it conftitutes a mixed 
metal, clole-grained, hard, and difficult to break. Melt 
in a crucible one half-part of fteel-filings, two of cobalt, 
and two of miiriat of foda : the mixture is foon in fufion. 
Bifmuth will not unite with iron. Antimony combines 
well with this metal by fufion : in the proportions of one 
part of iron, and two of antimony, it forms a hard alloy, 
with fmall facets, which fcarcely yields to the hammer. 
Iron has a flronger affinity with fulphur than with this 
brittle metal, and confequently is capable of decompo- 
fing fulphure of antimony. To effeft this, five ounces 
of the points of horfe-fhoe nails are heated red-hot in a 
crucible ; a pound of pulverized fulphure of antimony is 
then thrown in, and a ffrong heat fuddenly given to melt 
the mixture: the iron attacks the fulphur. When the 
mixture is well fufed, an ounce of nitre in powder is 
added, to facilitate the feparation of the fcorise from the 
.antimony. The mixture being fuffered to cool, anjtimo- 
S T R Y. 299 
ny is found in the crucible, which does not contain iron ; 
but, if one part of iron be ufed with two of fulphure of 
antimony, the antimony will be alloyed with iron-; this 
was called regulus of iron. The fcorise, which are found 
above the antimony alloyed with iron, and prepared with 
nitre and tartar, have a yellowifh colour, fimilar to that 
of amber, produced by the iron they contain, whence 
Stahl called them fuccinaiedfcoria. He directs them to be 
reduced into powder, and boiled in water, which takes 
up the moft fubtle part of the powder ; after which the 
fluid muff be decanted off, filtered, and the powder on 
the filter detonated three times its weight of nitre: this 
being vvaflied and dried, is Stahl's aperitive, and antimo- 
niated faffron of Mars. 
It is (till uncertain whether zink be capable of uniting 
with iron. Malouin has (hewn, that this metal may be 
applied, like tin, to the furface of iron, for the purpofe of 
defending it from the contaft of air, a circumftance which 
fhews that thefe two metallic matters are capable of com¬ 
bining. It feems that nickel is capable of being very in¬ 
timately united with iron, fince thefe two metallic fub- 
ftances can never beperfeftly feparated, as Bergman has 
demonftrated. 
Mercury does not contract any union with iron in its 
metallic date; it has in vain been attempted to unite 
thefe two metals immediately, but the combination is 
fuccefsfully made by prefenting them to each other in the 
ftate of oxyds. Navier has obferved, that a whitifh 
fnowy precipitate is obtained, by mixing a folution of 
iron and of mercury^ by the fulphuric acid, and evapo¬ 
rating the mixture; in this operation fmall fiat cryftals, 
fimilar to thofe of boracic acid, are formed. Navier af¬ 
firms, that thefe cryftals are a combination of iron and 
of mercury. Lead is not capable of uniting with iron. 
Iron and tin appear fufceptible of union by fufion. 
The preparation of white iron, or, as it is commonly 
called, tin,' which confifts of iron plates covered with^a 
thin ftratum of tin, fhews that this combination takes 
place. In order to tin iron, it is neceflary that the fur- 
face of the metal fliould be very clear and bright; for 
that purpofe it is corroded by an acid, or fometimes filed 
or feraped, or covered with a folution of fai-ammoniac ; 
it is afterwards plunged vertically into a vellel of melted 
tin, moved backwards and forwards, to increafe the con¬ 
tact, and when fufficiently tinned, it is taken out and 
rubbed with faw-duft, or bran, to clear off the fat or 
pitch with which the melted tin was covered, and which 
adheres to the furface of the tinned iron. With manga- 
nefe an alloy or mixture cannot be obtained, but by 
taking both the ironand the manganefe in the oxyd Hate : 
Take equal parts of the oxyd of iron and manganefe; 
make them into a pafte with oil: put the mixture into a 
crucible. A metallic button is obtained, brittle, ami 
granulated in the fra ft u re. 
By means of water, a preparation is made with iron, 
known by the name of martial Etbiops, or faffron. of Mars. 
There are a vafl many proceffes for obtaining Ethiops. 
The following are felefted as molt worthy of attention. 
1. That of Vauquelin. Take two parts of iron in fine 
powder, and one part of red oxyd of iron ; put the mix¬ 
ture into a covered crucible, and expofe it to a flrong 
heat for two hours. In this experiment, the iron takes 
a portion of oxygen from the red oxyd ; and, by . tlie ba¬ 
lance which is thus eftablifhed between the two portions 
of iron, makes the whole pafsinto'ablack homogeneous 
oxyd. 2. That of M. Save. Take hammerings of iron, 
and reduce them to powder; triturate this powder on 
marble with a little water; put the mixture into a cruci¬ 
ble, and heat it till it is entirely deprived of moifturej 
then pour in a few drops of oil, taking care to fpread 
them equally; and a very black oxyd is immediately 
produced, which is to be left fome time longer on the 
fire, in order to burn all the oil: reduce the clots which 
may be formed. A third method is, to work a certain 
quantity of iron-filings-into a pafte with water; then dry 
