An Improved Method of Treating Wood and other Materials to Protect the same against Fire and other Destructive Agencies.
Year: 1898

page_text: LL
Date of Application, 6th July, 1898
ALL
T
2000
1311
2000
An Improved Method of Treating Wood and other Materials to
Protect the same against Fire and other Destructive Agencies.
We, ALFRED JAMES DE HAILES and THEOPHILUS HORNE REDWOOD, Analytical
and Consulting Chemists, both of 15, Red Lion Square, and HENRY VALENTINE
SIMPSON, Lieutenant R.N., of 2, Army and Navy Mansions, Victoria Street,
Westminster, all in the County of London, do hereby declare the nature of this
invention to be as follows:-
Our invention is chiefly designed to afford the means for rendering wood and
other materials non-inflammable without imparting to them certain objection-
able properties which have heretofore arisen from the use of the chemical sub-
stances employed in the treatment of such materials.
Among the substances used for rendering wood or other materials non-in-
flammable the salts of ammonia are the most useful. The usual method of
applying these salts is in the form of an aqueous solution with which the
wood or other material is impregnated by any well known and suitable method.
A great disadvantage attending the use of some of these compounds or solutions
is their liability to attack and corrode metals in the presence of moisture so
that, in the use of wood that has been rendered non-flammable by treatment
with such solutions or compounds, it has been necessary to observe great care
with regard to its contact with metal structures or objects under conditions where
it would be exposed to the effects of the weather or atmosphere, the difficulty
arising from this liability being greatly increased when comparatively impure
materials, such as the commercial salts, are used. It is probable that a con-
siderable proportion of this corrosion is due not only to free acid in the com-
pounds or solutions but also to the partial decomposition of the salts themselves
and our invention is designed to overcome or mitigate the above mentioned
difficulty by availing ourselves of the property that these salts possess of forming
double salts with hydrates or oxides of certain metals. That is to say, we have
discovered, and make use of the discovery, that by using a solution of the hydrates
or the oxides of metals which form double salts with ammonium salts we can
prevent or greatly diminish the corrosion of metal used in contact with non-
flammable wood.
According to our invention we proceed as follows, ciz. we make a solution of
a hydrate or oxide-say, for example, oxide of zinc--with such a salt as sulphate
of ammonia with which the wood or other material is to be impregnated. We
subject the wood or other material to the action of this solution for a sufficient
time to thoroughly impregnate the same and then dry it in any suitable manner.
Our reason for using the oxide of zinc with the sulphate of ammonia is that we
may utilize the property possessed by such a salt, of forming a double salt with
the oxide so that in the drying of the wood or other material after its treatment
in the solution, when a portion of the ammonia is volatilized, the bi-sulphate
which is left is neutralized by the oxide present in the solution. Therefore the

page_text: wood will have the property of non-flammability and such other preservative or
protective qualities as may be due to the effects of the solution, without acquiring
to any great degree the objectionable character arising from the corrosive action
on metal.
An Improved Method of Treating Wood and other Materials to
Protect the same against Fire and other Destructive Agencies.
We, ALFRED JAMES DE HAILES and THEOPHILUS HORNE REDWOOD, Analytical
and Consulting Chemists, both of 15, Red Lion Square, and HENRY VALENTINE
SIMPSON, Lieutenant R.N., of 2, Army and Navy Mansions, Victoria Street,
Westminster, all in the County of London, de 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:—
Our invention is chiefly designed to afford the means for rendering wood and
other materials non-flammable without imparting to them certain objection-
able properties which have heretofore arisen from the use of the chemical sub-
stances employed in the treatment of such materials for the above purpose.
Among the substances used for rendering wood or other materials non-in-
flammable the salts of ammonia are the most useful. The usual method of
applying these salts is in the form of an aqueous solution with which the
wood or other material is impregnated by any well known and suitable method.
A great disadvantage attending the use of some of these salts is their liability to
attack and corrode metals in the presence of moisture, so that, in the use of wood
that has been rendered non-inflammable by treatment with such solutions, it has
been necessary to observe great care with regard to its contact with metal
structures or objects under conditions where it would be exposed to the effects
of the weather or atmosphere, the difficulty arising from this liability to corrode
being greatly increased when comparatively impure materials, such as the ordinary
commercial salts, are used. It is probable that a considerable proportion of this
corrosion is due not only to free acid originally present in the salts or solutions
but also to the partial decomposition of the salts themselves and our invention
is designed to overcome or mitigate the above mentioned difficulty by availing our-
selves of the property that these ammonium salts possess of forming double or
compound salts with oxides of certain metals. That is to say, we have discovered,
and make use of the discovery, that by using a solution of the oxides of metals
which form salts with ammonium salts we can prevent or greatly diminish the
corrosion of metal used in contact with non-flammable wood.
According to our invention we make a solution of an oxide-say, for example,
oxide of zinc with such a salt as sulphate of ammonia with which the wood or
other material is to be impregnated.
This solution may be maile as follows:-either (a) by dissolving oxide of zinc
in boric acid so as to obtain preferably a saturated solution and adding to this
solution the sulphate of ammonia in the proportion of lib. of boric acid to 6lbs.
of sulphate of ammonia or thereabouts, or (b) instead of dissolving the oxide of
zine directly in boric acid we may obtain the same result by mixing 100 parts of
sodium boráte (borax) dissolved in water with 75 parts of sulphate of zinc dissolved

page_text: in water and then dissolving the precipitate of zinc borate thus produced, in
a solution of sulphate of ammonia, in the proportion of about Glbs. of sulphate of
ammonia to 1lb. of the sodium borate, or (c) by dissolving oxide of zinc in a
solution of acetate of zinc by adding zinc oxide in any suitable proportion to a
hot solution of acetate of zinc, and adding sulphate of ammonia to this solution
in the proportion of about 6lbs. of sulphate of ammonia to 1lb. of acetate of
zinc.
We subject the wood or other material to the action of one or other of these
solutions for a sufficient time to thoroughly impregnate the same and then
dry it in any suitable manner.
Our reason for thus using the oxide of zinc with the sulphate of ammonia is
that we may utilize the property possessed by the latter, of forming a salt with the
said oxide, so that in the drying of the wood or other material after its treatment
in the solution, when a portion of the ammonia of the ammonium salt is volatilised,
the acid or bisulphate of ammonia which is left is neutralized by the oxide of
zinc present. The wood will therefore have imparted to it the property of non-
flammability and such other preservative or protective qualities as may be due
to the effects of the solution, without acquiring to any great extent the objection-
able character arising from the corrosive action on metal.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:
The improved method of treating wood or other materials by means of one
or other of the above named solutions substantially as and for the purposes
specified.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.