Improvement in the Manufacture of White Lead.
Year: 1896

page_text: Date of Application, 15th May, 1896
Complete Specification Left, 13th Feb., 1897-Accepted, 15th May, 1897
PROVISIONAL SPECIFICATION.
Improvement in the Manufacture of White Lead.
I ARTHUR HENRY SANDILAND of 137 Southgate Road Hackney in the County
of London Surgeon do hereby declare the nature of this invention to be as
follows:-
In the course of the manufacture of carbonate of lead (commonly known as white
lead) by what is known as the Dutch process, a salt known as the acetate of lead
and probably other salts are first formed-such salt or salts are not wholly converted
into the carbonate of lead by the existing process but adhere to the carbonate of lead
and become dissolved in the course of the washing and grinding in water to which
the carbonate of lead is subsequently subjected but being unknown or disregarded as
incapable of further conversion are thrown away in solution. The object of my
invention is to convert such acetate of lead and other salts (if any) into the carbonate
of lead. This object is attained by dissolving an alkaline carbonate or hydrate
(preferably a mixture of the two) in all the water which comes in contact with the
lead in the course of its manufacture into white lead and instead of throwing such
water away as at present as above mentioned and in order to recover therefrom the
salt so held in solution therein. The proportion of the alkaline carbonate or hydrate
(or mixture thereof) so to be dissolved depends upon the quantity of the lead salt
remaining in solution but an ordinary proportion would be seven ounces to every
twenty gallons of water. This alkaline carbonate or hydrate (or mixture as above
mentioned) when so dissolved acts upon the lead salt in solution and immediately
forms a carbonate of lead which sinks to the bottom of the containing vessel leaving
the water free from lead in any form.
The result of this process is a gain of five tons of carbonate of lead to every one
thousand tons of the output.
Dated this 14th day of May 1896.
Improvement in the Manufacture of White Lead.
I, ARTHUR HENRY SANDILAND of 137 Southgate Road, Hackney in the County
of London, Surgeon 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 :-
In the course of the manufacture of carbonate of lead (commonly known as white
lead) by what is known as the Dutch process, the salt known as the acetate of lead
and probably other salts are first formed. Such salts are not wholly converted into
the carbonate of lead by the existing process, but adhere to the carbonate of lead
and become dissolved in the course of the washing and grinding in water to which
the carbonate of lead is subsequently subjected, and being unknown or disregarded

page_text: as incapable of further conversion are thrown away in solution. The object of my
invention is to convert such acetate of lead and other salts (if any) into the carbonate
of lead.
This object is attained by dissolving an alkaline carbonate or hydrate but pre-
ferably a mixture of the two in all the water which comes in contact with the
lead in the course of its manufacture into white lead instead of throwing such
water away as at present as above mentioned and in order to recover therefrom the
salt so held in solution. The proportion of the alkaline carbonate or hydrate or
mixture thereof so to be dissolved depends upon the quantity of the lead salt
remaining in solution a specified quantity of the alkali producing a similar quantity
by weight of the carbonate, but I have found a suitable proportion to be 7 ozs. to
every 20 gallons of water.
This alkaline carbonate or hydrate (or mixture as above mentioned) when so
dissolved acts upon the lead salt in solution and immediately forms a carbonate of
lead which sinks to the bottom of the containing vessel leaving the water free from
lead in any form.
The result of this process is a gain of five tons of carbonate of lead to every
1000 tons of the output.
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. In the manufacture of white lead the conversion into carbonate of lead of the
lead salts contained in solution in the waters of manufacture by dissolving therein
an alkaline carbonate or hydrate or a mixture of both substantially as described.
2. In the manufacture of white lead the recovery of carbonate of lead from the
waters of manufacture substantially as described.
Dated this 8th day of February 1897.
ARTHUR HENRY SANDILAND.