CERTAIN IMPROVED MATERIALS FOR USE IN PAINTING
Year: 1852

page_text: LETTERS PATENT to James Murdoch, of Staple Inn, in the County
of Middlesex, Patent Agent, for the Invention of "CERTAIN
IMPROVED MATERIALS FOR USE IN PAINTING."- A communication.
Sealed the 21st January 1853, and dated the 30th November 1852.
PROVISIONAL SPECIFICATION left by the said James Murdoch
at the Office of the Commissioners of Patents, with his Petition,
on the 30th November 1852.
I, JAMES MURDOCH, do hereby declare the nature of the said
Invention for "CERTAIN IMPROVED MATERIALS FOR USE IN PAINTING"
to be as follows:-
The improved materials are intended to be used as "driers," in
painting, when white of zinc is employed in lieu of white lead; and
they are prepared by combining the protoxides of certain metals
with acids having sufficient affinity for them to protect them from
the action of the air, and at the same time not sufficient to prevent
them operating quickly upon the oils employed in painting, so as to
render them "drying."
The protoxides employed are those of manganese, cobalt, iron,
tin, and nickel, preferably the protoxides of manganese and cobalt;

page_text: and the acids are preferably the benzoic, uro-benzoic, and the boric;
resins.also, which, from their acid properties, have the same effect
as the acids above nained, may be employed for the purpose.
SPECIFICATION in pursuance of the conditions of the Letters
Patent, filed by the said James Murdoch in the Great Scal
Patent Office on the 28th May 1853...
-
TO ALL TO WHOM THESE PRESENTS...SHALL-COME,-I,
JAMES MURDOCH, of Staple Inn, in the County of Middlesex, Patent
Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of November, in
the year of our Lord One thousand eight hundred and fifty-two,
in the sixteenth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said James Murdoch, Her spe-
cial license that I, the said James Murdoch, my executors, administra.
tors, and assigns, or such others as I, the said James Murdoch, my
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain
-and-Ireland, the Channel-Islands, and Isle of Man, an Invention for
"CERTAIN IMPROVED MATERIALS FOR USE IN PAINTING," communicated
to me from abroad, upon the condition (amongst others) that
I, the said James Murdoch, by an instrument in writing under my
hand and seal, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be per
-formed,-and-cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said James Murdoch, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascer
tained in and by the following statement thereof (that is to say):-
}

page_text: The object of the Invention is to provide improved materials to
be used as "driers" in painting, where white of zinc is employed
in lieu of white lead. Since the introduction of white of zinc as a
substitute for white lead in painting, attention has naturally been
turned to finding a material to replace litharge as a "drier," which
shall be free from those objections which havo led to the disuse of
white lead, viz. the injurious effects produced upon it by the action
of the vapours of sulphuretted hydrogen.
It has been long known that several oxides and metallic salts,
especially sulphate of zinc, umber, and oxide of manganese, had the
property, when combined with oils, of rendering them drying,
although not so effectual for this purpose as white lead. To these
substances may be added to oxides (or protoxides) of iron, cobalt,
nickel, and tin. These oxides, however, are for the most part
either difficult to prepare, or undergo rapid alteration when exposed
to the air, and therefore cannot be preserved or employed in practice
in their natural state; but the authors of the present Invention have
discovered that by combining the protoxides of iron, tin, nickel,
cobalt, and manganese, with substances which will protect them from
the oxygen of the air, they will retain their property of rendering
oils drying; and it is the addition of such substances to the above
named protoxides which forms the basis of the Invention. The
substances the best adapted to this purpose are acids, and especially
the benzoic, succinic, uro-benzoic, and boric, although any acid
having sufficient affinity for them, rendering the manufacture of the
drier more easy and economical, and the product capable of being
kept without alteration from the atinosphere, may be employed.
Of the substances named, the uro-benzoate and the borate of the
protoxide of cobalt are to be preferred; or, in an economical point of
view, the uro-benzoate and the borate of the protoxide of manga-
nesc, and the several compounds, may be prepared in the manner I
am about to describe.
The benzoate of cobalt, benzoic acid, is to be dissolved in boiling
water, and then saturated gradually by the addition of carbonate of
cobalt in fine powder (constantly stirring the liquor) until there is

page_text: no longer any effervescence, and that the blue test paper is no longer
reddened by it; it is then filtered, to separate the excess of carbo-
nate, and the liquor is then evaporated to dryness, and afterwards
heated until it has lost its water and taken a clear brown tint. By
this means is obtained a solid amorphous material, easily reducible
to powder, and which will keep in the state of powder under all tem-
peratures, merely wrapped in paper.
The benzoate of manganese is prepared in the same way, only sub-
stituting the carbonate of manganese for the carbonate of cobalt.
The uro-benzoates of cobalt and of manganese are prepared in the
same manner as the benzoates of the same bases, and are preferable
for manufacturing purposes, as being cheaper.
Borate of cobalt, a soluble salt of cobalt, say the sulphate, is to be
dissolved in cold water, and is precipitated by adding borax dis-
solved in cold water, the precipitated borate of cobalt is then col-
lected upon cloths and washed in cold water and dried in the open air.
The borate of manganese is prepared in the same manner, sub-
stituting for the salt of cobalt a soluble salt of manganese, for
example, the chloride, on account of its cheapness.
Resins which, by their acidity, have a similar effect to acids,
as described above, may be employed in the preparation of driers,
having no injurious effect upon paintings, and retaining their pul-
verulent state. These driers may be prepared by the following
process. An alkaline resinate of potash or soda is to be dissolved in
hot water, and the solution is to be precipitated by a suitable quan-
tity of the sulphate or chloride of pure cobalt or manganese. The
precipitate which is formed is an insoluble resinate of cobalt or
of manganese, which is to be collected on cloths and dried. Col-
lected thus in an amorphous state, it is to be reduced to powder,
and preserved like the other drying salts, having the same proper-
ties and being employed in the same manner and the same propor-
tions.
The proportion in which these improved drying salts should be
added to the white of zinc is about three parts of drier to one thou-
sand of white of zinc; but if the borate of manganese (which is the

page_text: most rapid of them all in its action) be employed much in excess
of these proportions, it is apt to produce a discoloration in the
painting, especially in the white grounds; it is therefore recom-
mended to mix one part of this drier in powder with twenty-three
parts of white of zinc in powder, in which state the mixture may be
kept ready for use kegs or in paper bags; and when required for
use, about seventy-two parts of the mixture may be added to one
thousand parts of white of zinc, but an excess of fifteen to twenty
per cent. of the mixture will not produce any discoloration in the
painting.
Having thus described the nature of the Invention, and the
manner of carrying the same into effect, I claim in respect thereof
the manufacture of "driers" for painting, by combining the pro-
toxides of cobalt, tin, iron, nickel, or manganese, with substances
capable of protecting them from the oxygen of the air, so as to keep
them in a pulverulent state; the substances which I prefer for this
purpose being those herein-before mentioned, viz. the benzoic, uro-
benzoic, succinic, and boric acids, and the acid resins.
In witness whereof, I, the said James Murdoch, have hereunto
set my hand and seal, this Twenty-eighth day of May, in the
year of our Lord One thousand eight hundred and fifty-three.
Witness,
E. C. COLE.
JAMES MURDOCH. (L.S.)