CHEMISTRY. 
3°4 
iron. During its combination with the former hydrogen 
gas is evolved. It appears from Rinman’s experiments 
to be difficult to faturate the fluoric acidWith iron. 'By 
boiling the foiution, a copious precipitation of the oxyd 
of iron is produced. Fiuat of iron does not cryftallize. 
It is decompofed in the lire, and by alkalis am,! earths. 
It is decompofed alfo by the fulphuric, nitric, and muri¬ 
atic, acids. The boracic acid, diluted with water, dif- 
folves both the metal and the oxyd of iron by the aflii- 
tance of heat. The foiution, which has the colour of 
amber, depofites, by Handing, a yellow ochry precipitate, 
and, by evaporation, fafciculated yellovviilr cryftals. If 
a foiution of borax be mixed with a foiution of fulphat 
of iron, a borat of iron is formed, which is very difficultly 
folublein water. This, fait is decompoled by alkalis, 
and by all the acids except the carbonic Oxalat of iron, 
with an excefs of acid, is eaiily ibluble in water. If the 
oxalic acid be faturated with the oxyd of iron, a whitifti 
infoluble precipitate is formed This acid has the ftrong- 
eft affinity of all the acids for iron. The citric acid.dif- 
folves iron readily with the evolution of hydrogen gas. 
The faturated foiution is of a dark colour. With time 
it becomes muddy, black, and thick. This fait is but 
little known. The malic acid difiblves iron, according 
to Scheele, and forms with it a deliquefoent fait. The 
benzoic acid aCts weakly on the metal, but more power¬ 
fully on the oxyd of iron. The foiution affords cryftals, 
which have a fweetifh tafte, and efflorefce in the air. Ben- 
zoat of iron is foluble in alcohol Succinic acid affords 
a (lightly coloured foiution by digeftion with iron, and 
.an ochry precipitate, the nature of which has not been 
invefiigated. During the foiution of iron in liquid ar- 
lenic acid, hydrogen gas is difongaged. Scheele remarks 
that this foiution often forms into a jelly in open, but 
never in ciofe, veftels. Alkalis precipitate the arfeniat of 
iron of a greenifh white colour, which becomes reddilh 
by expofure to a glow heat. If one part of iron filings 
be diftilled with four of arfenic acid, a fpontaneous in 
(Summation is produced, by which the acid is converted 
into the oxyd and metal of arfenic Arlenic acid preci¬ 
pitates the acetat of iron of a dark green. The neutral 
arfenical lalts decompole all the acid (oiutions of iron. 
Arfeniat of iron is eaiily decompofed by calcining it with 
charcoal. The arfenic acid has very little aCtion on the 
oxyd of iron. 
Iron confiderably increafes. the fufibility of earths, ef- 
pecially the oxyds of iion ; for, in its metallic irate, it 
does not unite with them. Common glafs owes its os- 
lours to the iron which is accidentally mixed with the 
materials it' is compofed of. Fixed alkalis and ammoniac 
.have no aCticn upon iron, unlefs combined with water. 
When digefted in this manner for a few days, the liquor 
becomes thick, and precipitates a fmal! quantiry ofobiack 
oxyd of iron. Hydrogen gas is di(engaged, which proves 
tl c neceifity of water, fince that is decompofed. Mix 
fulphat ofpotafh with half the quantity of filings of iron; 
heat them in a crucible : when cool, the fulphat will be 
found in the ftate of a fulphure. 1 his fuiphure, by iixi- 
viation, furnifhes a liquor of a very dark green colour; 
a few drops of nitric acid will make this colour difap- 
pear. The greateft part of the iron oxydated by the 
oxygen of the fulphuric acid, remains undiflolved in the 
water of lixiviation ; and acids difengage from this oxyd 
a large quantity of lulphurated hydrogen gas. 
A fait is prepared for medical ufes, with ammoniacal 
muriat and iron, which is called martialflowers offal-am- 
,mo)iiac , or ens martis. One pound of ammoniacal muriat 
in powder, and one ounce of iron filings, are mixed to¬ 
gether. The mixture is expofed in an earthen veflel, 
covered with a veflel of the lame kind, to a heat capable 
of igniting the lower part of the apparatus : in five or fix 
hours a yellow matter is fublimed in the upper veflel. In 
this experiment the muriat is not decompofed ; for the 
produff is fublimed muriat of ammoniac coloured by a 
portion of oxyd of iron. To make a complete decom- 
pofition, two parts of the filings mud be ufed witYorve 
of the muriat; diftil in a retort with the pneumatic p. 
paratus, and liquid ammoniac is obtained/ charged with 
a little iron when that ammoniac is received in water. 
The refidue is muriat of iron. The oxyd of iro . is much 
better for the above operations. Iron, or the fulphure of 
iron, martial pyrites, burns rapidly, but without noife, 
when triturated in a metal mortar with fu.per-oxygenated 
muriat of potafti; this mixture in a heap (truck with fteel, 
detonates ftrongly, and gives out a red flame. 
Gold unites eaiily w th iron, and by this union becomes 
harder and iefs malleable. In the proportion of fix parts 
of gold to one of fteel, the metallic mixture may be beat 
out into plates without cracking. Iron is only partially 
feparated by combuftion in a glow heat. It has a ftrongec 
attraction than gold for the oxygenated muriatic and nf- 
tro-muriatic acids, and precipitates gold from thele acids 
in its metallic (fate. Silver combines readily with iron. 
A mixture of fourteen parts of fiiver, and two one-half 
of iron, is more elaltic than (liver, attraCts the magnet, 
and is not decompofet in a llrong fire. A (mall portion 
of iron does not feem to injure the colour or malleability 
of the fiiver. Iron precipitates fiiver from all its (oiutions 
in acids: but this happens in the nitric only, when the 
acid is not completely faturated, or when nitrous gas is 
.added. Muriat of fiiver is decompofed in the dry way 
by diftillauon with iron filings; Iron precipitates mer¬ 
cury in its metal.:c (Late from its foiution in acids. Dif¬ 
tilled with oxygenated muriat of mercury the muriat is 
decompofed, and fluid mertuiy pioduced. Sulphat of 
iron precipitates mercury from its iolution in nitric 
acid in its metallic ftate. Lead is precipitated from its 
(elutions in acids by. iron. It alfo precipitates bifmuth 
from its acid folutions, and in the dry way takes from 
it the (ulpbur which it contains. Nickel has the ftrongeft 
affinity of all the metals for iron, and is (tparated from 
it with the greateft difficulty The admixture of nickel 
does not injure the malleability of the iron, but rather 
Items to increafe it It renders the iron lels futible. 
Nickel is precipitated only in a very impeded! manner 
by iron frou its (oiutions in acids. Iron unites in dole 
veliels with arfenic. 1 his combination renders the iron 
more brittle, and diminifhes its attraction for tlie magnet. 
It is feparated from the iron with difficulty, 
The ules of iron are fo great and extenfive, and be- 
fides fo well known, that it would be uieleis to attempt 
to enumerate them: it is only nec.efTj.ry to obferve, that 
no art can be carried on without it, and that it is the foul 
of ail the arts. The different modifications it is fuiceptible 
of, render it very proper for the multiplicity o'f purpofes 
to which it is applied. Call-iron (erves to form utenfils 
of various degrees of folidity as may be required. The 
hardnefs and tenacity of the (everal kinds of forged iron 
are no lefs applicable to other ules. The fame obfervation 
is applicable to fteel: the finenels of the grain, and ex¬ 
cellence of the temper, conlhtute a great number of 1'pe- 
cies, peculiarly adapted to an- ainsoft infinite number of 
arts. The oxyds of iron lerve to give a red or brown 
colour to porcelain, enamel, pottery, &c. they are like- 
wife ufed in the preparation of artificial precious Hones, 
and combined with oil for painters. Iron is the bafis of 
an important medicine, which is frequently applied with 
the greateft fuccefs. It is the only metal which is not 
noxious, and whofe effeCts are not to be feared ; it has 
fuch an analogy with organic matters, that it teems to 
form part of them, and often owes its production to the 
procefles of life or vegetation. The effeCts of iron on 
the animal economy are numerous; it ftimulates the 
membranes of the vifoera, and appears to aCt more efpe- 
cially on thole of the mufcles, which it braces ; it forti¬ 
fies the nerves, and gives a remarkable degree of force 
and vigour to the animal fyftem; it excites many fecre- 
tions, efpecially the urinary and menftrual evacuations 5 
it increafes the contractions of the heart, and confe- 
quently renders the pulfe ftronger' and quicker. Its ac- 
