Improvements in the Production of a Substitute for White Lead and of other Oxysalts of Lead from Lead Sulphate and Lead Chloride.
Year: 1896

page_text: Date of Application, 28th Apr., 1896-Accepted, 25th July, 1896
COMPLETE SPECIFICATION.
Improvements in the Production of a Substitute for White Lead
and of other Oxysalts of Lead from Lead Sulphate and Lead
Chloride.
I, SOLOMON GANELIN, 623 Parrish Street, Philadelphia, Pennsylvania, U.S.A.,
Chemist, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
My invention relates to novel methods for converting lead chloride or lead
sulphate into oxysalts of lead of which one, namely, oxychloro-carbonate of
lead, is a new compound and constitutes a desirable substitute pigment for
white lead.
According to my invention obtain oxysulphate of lead from lead sulphate and
oxychloride of lead from lead chloride of the definite chemical compositions PbO.
PhSO, and PbO. PbCl, by using as a base magnesium oxide (MgO) which differs
radically from all bases hitherto employed for this purpose, for example, it is
immaterial whether the quantity of magnesium oxide employed is more or less
than half the equivalent weight of lead chloride or lead sulphate used.
whatever proportions the magnesium oxide and lead chloride or lead sulphate are
taken the definite chemical compounds PbO. PbSO, or PbO. PbCl, are invariably
formed. If the quantity of magnesium oxide exceeds half the equivalent weight
of lead chloride or lead sulphate, the excess of magnesium oxide remains unattacked.
Similarly if the quantity of lead salt exceeds double the equivalent weight of
magnesium oxide, the excess remains unattacked and in all cases the definite
chemical composition of the oxysalts PbO. PbSO, and PbO. PbCl, is produced.
Moreover, it is not necessary to bring either the magnesium oxide or the lead salt
into solution, because magnesium oxide in the solid and damp state re-acts upon
the lead salts in a similar state and produces oxychloride of lead of definite
chemical composition and of snow white color. To carry my improved method
into effect, I take lead sulphate or lead chloride and mix or stir it with half of its
equivalent weight of oxide or bydroxide of magnesium in the presence of sufficient
water to form a paste. I then add more water until the following reaction takes
ploce
However, it must be borne in mind that for the reasons stated the quantities of
magnesium oxide and lead salt referred to in the equation need not he adhered to
and may be increased or diminished without changing the white color and definite
chemical composition of the resultant oxysalts.
To manufacture oxysalts of lead of any desired acid radical from lead sulphate,
I intimately mix or stir it with half its equivalent weight of oxide or hydroxide of
a base more basic than lead in the presence of water and a salt of the desired acid
radical. Upon the completion of the ensuing reaction there will be formed
dependent upon the salt used, an oxysalt of lead containing the acid radical of the

page_text: particular salt employed. The foregoing may bemore clearly expressed by means,
for example, of the following equations:
1
(1) 3 PыSO + 2 NaHO + 2 NaCl + Na,CO₂ = PbCO₂. PbCl.
Pb(OH), +3 Na,SO
From the five preceding equations, it will be apparent that the salts and hydroxide
used may be taken in different proportions having reference to the equivalent
weight of lead sulphate employed and it must be understood that any salts of
which the acid radical forms an insoluble salt with lead may be substituted for the
particular salts mentioned. Moreover in pursuance of my invention I may produce
oxycloride of lead from lead sulphate by the use of lead oxide and an alkaline
chloride by means of a reaction of two phases. The reaction considered as a whole
is fully shown by the following equation:
2 PbSО + 2 РыO +4 NaCl 2 (PbO. PbCl₂) + 2 Na₂SO.
=
and the alkaline hydroxide thus formed reacts according to the following equation
which is the one above.given :
2 PbSO, +2 NaOH + 2 NaCl = PbO. PbCl, + 2 Na,SO + H₂O.
It may be remarked that in cases where I desire to form an oxychloride from
impure sulphate of lead in which a metallic oxide is present in sufficient quantity
to convert all the lead sulphate into oxychloride, I apply sodium chloride to such
impure lead sulphate without using any metallic oxide other than that already
present in the impure sulphate. In practice I have attained good results by using
sulphate of lead in which oxide of zinc and oxide of lead were present in such
quantities that it was not necessary to add more oxide, it being sufficient to add

page_text: chloride of sodium. In the same manner I have obtained oxychloro-carbonate of
lead from lead sulphate, which contained the oxides of zinc and lead and which is
known as sublimed lead, by grinding such sublimed lead with sodium chloride and
sodium carbonate in the presence of water.
For the sake of a further explanation of my invention, I would state that my
improved white lead substitute or admixture is more readily produced than white
lead of commerce and it may be prepared in the manner above set forth or from
oxychloride of lead by the addition thereto of alkaline carbonate or bi-carbonate
in such quantities that there is not sufficient carbonate or bi-carbonate present for
replacing the chlorine of the oxychloride of lead. By this mode of procedure
there is formed an insoluble admixture or compound which constitutes my
improved pigment and a soluble salt, the reaction being shown by the following
equations:
(3) 4Pb(OH)Cl + Na,COs + NaHCO,= Pb(OH),CO.. PbCO,.
Pb(OH)Cl + 3 NaCl + H₂O.
However, the foregoing equations are general and are not intended to be exact,
but are stated merely for purposes of description. Upon the completion of the
above mentioned reaction, the precipitate which comprises the chemical compound
or admixture, oxychloro-carbonate of lead may be filtered and washed and dried
and preserved for use.
If the oxychloride of lead from which my improved pigment is produced in the
manner above described is not pure but contains sulphate or oxysulphate of lead,
then there is present in the product, sulphate or oxysulphate of lead. However,
my invention covers oxychloro-carbonate of lead whether sulphate or oxysulphate
be present therein or absent therefrom.
It will be obvious to those skilled in the art to which my invention appertains
that modifications may be made in details without departing from the spirit thereof,
for example, my invention covers making any one of the salts separately and apart
from the others.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The within described improvements in producing lead oxysalts of one or more
acid radicals and of which one constitutes a novel substitute for white lead.
2. A new and useful white lead substitute, to wit, the chemical compound,
oxychloro-carbonate of lead.
3. The herein described method of making a substitute for white lead, to wit,
oxychloro-carbonate of lead which consists in treating oxychloride of lead with an
alkaline carbonate or bicarbonate in such quantities that the carbonate or
bicarbonate does not replace the entire amount of chlorine of the oxychloride, and
separating the soluble from the insoluble matter in the resultant product.
4. The herein described method of making the definite chemical compounds PbO.
PbSO, and PbO. PbCl, from lead sulphate and lead chloride which consists in
mixing the lead salt in the presence of water with magnesium oxide or hydroxide.
5. The herein described method of making oxysalts of lead from lead sulphate
which consists ip treating lead sulphate in the presence of water and an oxide of a
metal more basic than lead with a salt of which the acid radical forms insoluble
salt with lead.
6. The herein described method of forming lead oxysalts of more than one acid
radical from lead sulphate which consists in treating lead sulphate in the presence

page_text: of water and an oxide of a metal more basic than lead with salts having the desired
acid radicals which form insoluble salts with lead.
7. The herein described method of forming oxychloro-carbonate of lead from
lead sulphate which consists in treating lead sulphate in the presence of water and
of the carbonate, chloride and hydroxide of an alkaline base, substantially as
.described.
8. The herein described method of converting all the lead present in an
uncombined mixture of lead oxide and lead sulphate by means of sodium chloride
-and water, which consists in mixing said ingredients in sufficient quantities for
effecting the following reactions: first, the conversion of the lead oxide into
oxychloride and the consequent formation of hydroxide of sodium, and second, the
conversion of the lead sulphate by means of said sodium bydroxide into oxychloride
-of lead, substantially as set forth.
Dated, at Philadelphia, this 9th day of April 1896.
SOLOMON GANELIN.
Boult & Wade,
Agents for the Applicant.