2 9 6 £ C H E M 
with a knife, but loftes its brilliancy fooner than lead; 
and, when melted with the blow pipe upon a coal, the 
phofphorus burns, and quits the lead. 
The alloy of lead with arfenic has not been examined. 
Nickel, manganefe, cobalt, and zink, do not unite with 
lead by fufion. Antimony forms a brittle alloy with 
fome brilliant facets, fimilar in texture and colour to iron 
or fte'el, according to the proportions of the mixture, 
and of a fpecific gravity more confiderable than the two 
metallic i'ubftances, feparately taken, would compote. 
Lead alfo combines with bifunith, and affords a metal of 
a fine and dole grain, which is very brittle. Mercury 
dillolves lead with the greateft facility ; this amalgam is 
made by-pouring hot mercury into melted lead. It is 
white and brilliant, and becomes folid at the end of a 
certain time. Lead unites very eafily by fufion with tin. 
Two parts of lead, and one of tin, form an alloy more 
fufible than either of the metals taken feparately, and 
conftitutes the folder of the plumbers. Eight parts of 
bifinuth, five of lead, and three of tin, compofe an al¬ 
loy fo fufible, that the heat of boiling water is fufficient 
to melt it. Tin and lead melted together, become reci¬ 
procally oxydated : thele two oxyds compounded toge¬ 
ther form the balls of different enamels, and the glafing 
of delft-ware. The ufual way is to calcine one hundred 
parts of lead and thirty of tin in an oven ; mixjrhe oxyds 
with one hundred parts of fand and thirty of potalh : 
melt this mixture, and the produft will be a white opake 
glafs, called white enamel. This enamel may be colour¬ 
ed at pleafure by means of the metallic oxyds. 
Lead is not altered by pure water, becaufe the princi¬ 
ples of the water are not feparated by that metal; yet the 
internal parts of lead pipes which coijduft water are co¬ 
vered with a whitilh cruft, or a kind of cerufe, which 
doubtlefs is produced by the aftion of the different fub- 
ftances contained in the water on this metallic fubftance. 
Mr. Luzuriaga has obferved, that by agitating granu¬ 
lated lead in a fmall quantity of water, with the contact 
of air, the metal becomes quickly oxydated. 
This metal is foluble in all the acids; but concentrat¬ 
ed fulphuric acid does not attack it, except it be boiling, 
and the lead be in fmall pieces. In this procefs fuiphu- 
reous acid gas paffes over. When moll of the acid is de- 
compofed, the mixture is white and dry, and feparates 
into two portions, on being wafhed with diftilled water. 
The moll confiderable part is infoluble in water, and is 
an oxyd of lead containinga little fulphuric acid, formed 
by the oxygen which the metal has taken from the acid 
during the time of the dilengagement of the fulphureous 
gas. The other portion, foluble by water, is a combi¬ 
nation of fulphuric acid and oxyd of lead; this folution, 
by evaporation, affords fmall needles of l'ulphat of lead. 
It is decompofed by fire alone, and alfo by lime and al¬ 
kalis, and then becomes a fulphure. The nitric acid ap¬ 
pears to aft very ftrongly on lead : Pour into a matrafs 
two parts of weak nitric acid upon one of lead-filings; 
place the matrafs on a warm land-bath : the nitric acid 
diffolves the lead, and, during.the lolution a grey pow¬ 
der is precipitated, which Groffe took to be mercury; 
but Baume affirms that this matter is nothing but a por¬ 
tion of the oxyd of lead. This folution does not afford 
a precipitate on the addition of water. Its cryftals, ob¬ 
tained by cooling, are of an opake white, in the form of 
flat triangles, whofe angles are truncated ; the fame iolu- 
tion, by a flow evaporation of feveral months, affords 
cryftals, the largeft one inch in thicknels, of the form of 
hexlahedral pyramids, whole three faces are alternately 
large and fmall, and whofe point is truncated, io that 
each cryftal is an eight-fided folid. The nitrat of lead 
decrepitates in the fire, and melts with a yellowilh flame 
when laid on ignited charcoal. The oxyd, which is at 
fiift yellow, becomes quickly reduced into globules of 
lead. If this fait be diftilled ill clofevefiels with a ftrong 
heat, it gives out a confiderable quantity of oxygen gas. 
Mixed with inflammable lubftances, it detonates in the 
I S T R Y. 
fire, and has, on that account, been termed fulminating 
lead This la.lt is decompofable by lime and alkalis. 
The fulphuric acid, though it afts but feebly on lead, 
has neverthelefs a llronger affinity to the oxyd of this me¬ 
tal than the nitric acid. If pure fulphuric acid, or any 
neutral, earthy, or alkaline fulphuric fait, be added to a 
nitric folution of lead, a white precipitate is formed in a 
very fhort time : this precipitation takes place, becaufe 
the fulphuric acid, feizing the oxyd of lead, forms with 
it fulphat of lead, fimilar to that which is prepared by 
the immediate combination of the fulphuric acid with 
that metal. 
The pure muriatic acid, by the affiftance of heat, oxy- 
dates lead, and jjdiSolves part of its oxyd ; but it is diffi¬ 
cult to faturate it completely. This metal becomes 
more readily and intimately combined with the muriatic 
acid, by adding the acid itfelf, or the acid united with 
an alkaline or earthy bafe, to a folution of nitrat of lead. 
A white precipitate is immediately formed, which is 
much more abundant than that produced by the fulphu¬ 
ric acid, and relembles a coagulum. It is a combina¬ 
tion of the oxyd of lead with the muriatic acid, which 
has feparated the oxyd of this metal from the nitric acid. 
This fait falls down, becaufe it is much lefts foluble ia 
water than nitrat oft lead ; if it be expofed to heat, it gives 
out vapours, whole talle refembles fugar, and melts into 
a brown mafs, called corneous had. It is foluble in thirty 
times its weight of boiling water. The lolution of this 
fait by evaporation cryllallizes into fmall, fine, and bril¬ 
liant needles, which form bundles, or unite by one of 
their extremities in an obtufe angle. This fait has a 
lvveetilh tafte; it melts eafily, and in cooling takes the 
fliape of a horn, whence the name Corneous lead, though 
Fourcroy gives a different interpretation; it may then 
be cut and flatted ; lime and alkalis decompofe it. 
The oxygenated muriatic acid dillolves lead ; if added 
in a certain proportion, the folution becomes red: thus 
may be obtained a fuper-oxygenated muriat of lead. 
Phofphoric acid combines with the oxyh of lead, but 
not with the metal. Boracic acid will not attack lead; 
but a borat may be formed by decompofing nitrat of 
lead; it may be obtained alio by rfleans of its oxyds. 
Fluoric acid has, i'ome action on lead, but the effeft is 
much llronger on the oxyds. The oxyds of lead feem 
to have a ftrong attraftion for carbonic acid ; but this 
acid does not difl’olve lead’either in its metallic or oxyd¬ 
ated Hate. 
Oxyd of lead unites with filex. The fame oxyd, added 
to common glafs, does not alter its tranfparency, but 
gives it a greater degree of weight, and more efpecially a 
kind of unftuoufnefs, which renders it capable of being’ 
cut and poliffied more _ eafily without breaking. This 
glafs is very proper to form achromatic lenfes ; buj: it is 
lubjeft to veins, and to have a gelatinous afpeft.’ It is" 
called flint glafs. 
Lead is oxydated by nitrat of potalh, or nitre. With 
this, neutral lalt in powder is thrown on the melted metal 
in a low red heat, it excites fcarcely any detonation or 
apparent flame, though the lead is oxydated'and vitrified 
by the alkali of nitre, and takes the form of fmall yel¬ 
lowilh feales, fimilar to litharge. Lead decompoles am- 
moniacal muriat by the affiftance of heat. For this pur- 
pofe, take two parts of muriat of ammoniac in powder, 
and - two or three parts of red oxyd of lead : put the mix¬ 
ture into a ftone retort, and place it in a reverberating 
furnace; adapt a balloon to the neck of the retort, and 
from this mull go a tube, which is to be plunged into a 
Woulfe’s bottle, containing a quantity of water equal to 
the muriat of ammoniac ; lute the joinings, and proceed 
to diftillation with a gradual fire, which mull be in- 
creafed towards the end of the operation, fo as to make 
the retort red-hot. Very pure and very cauftic ammo¬ 
niac paffes over; when no more ammoniac comes over, 
the operation is ended. The mafs which remains in the 
retort after the decompofition is muriat of lead, which 
melts 
