An Improved Process for Hardening Stone.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
An Improved Process for Hardening Stone.
THOMAS ROUGHT JONES 27 Glasbury Road West Kensington, W. Gentleman do
hereby declare the nature of this invention to be as follows:-
My invention is an improved process for hardening stone such as Portland stone and
other Stone of a like character and consists of placing the Stone to be hardened in a
Vacuum and thus exhausting the air contained in the Stone and while in Vacuum
introducing a Solution of Sulphate of Zinc which readily penetrates stone exhausted
of its air, the saturation may be continued when the Stone is withdrawn from Vacuum
the Action of the Sulphate of Zinc is to combine with the lime in the Stone and harden
it to the extent of the penetration or there abouts and this action is most rapid under
my Vacuum process.
Dated this manty coventh day of Inle 1900
An Improved Process for Hardening Stone.
I, THOMAS ROUGHT JONES of 27 Glasbury Road West Kensington, Gentleman 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 has reference to a process for hardening Stone for the purpose of
preserving it from the effects of climate and of preventing the disintegration thereof.
It will be understood that the disintegration of Stone arises amongst other causes from
the absorbtion of moisture into the pores, which moisture is evaporated by heat or
acted upon by frost, so that a crumbling or what is known as "Weathering" of the
surfaces takes place. The disintegration or Weathering being more or less intense
according to the degree of exposure to which the stone is subjected.
Now according to my invention I am able to overcome these objections and to so
treat the stone that it will become practically impervious to the action of moisture,
and will consequently become more lasting.
I will now proceed to describe my invention, no drawings being necessary. The
stone to be treated is cut sawn or carved into the required dimensions and form
and is allowed to stand in a dry atmosphere in order to evaporate moisture. I
accomplish this preferably by subjecting the stone to the action of a current of dry
air, which may be supplied by a Fan, Blower or equivalent apparatus. When the stone
is dried to the required condition, I cause it to be placed into a chamber, Vessel or
Tank which is capable of being hermetically sealed, and in connection with which I
employ an Exhaust pump for the purpose of extracting the air and causing a partial
vacuum.
The length of time to which the stone is subjected to this partial vacuum being
dependent upon the nature and dimensions of the stone to be treated. I connect with

page_text: the said Chamber or Vessel, a pipe or pipes and a Valve or valves, which communicate
with a receptacle containing a metallic solution such as Sulphate of Zinc, which
solution is preferably heated to a temperature of 120° to 140° Fab.
Whilst the stone within the chamber or Vessel is under the action of the partial
Vacuum, I cause a valve or valves to be opened so as to admit a quantity of the
solution sufficient to cover the stone block or blocks, so that the pores of the stone
immediately commence to absorb the solution, with the result that they eventually
become filled with the metallic salt to a considerable distance beneath the surface.
During the time that the, solution is being. admitted, the partial vacuum is
maintained to the required degree, but when the stone block or blocks are completely
covered by the solution the vacuum is dispensed with. The length of time to which
the stone is subjected to the action of the metallic salts is dependent upon the bulk
and density of the stone.
The stone is then removed from the chamber or Vessel and when dried is ready
for use.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is:-
The herein described process for hardening stone, consisting essentially in subjecting
the stone to the action of a Vacuum or partial Vacuum and the introduction whilst in
that condition of a solution of Metallic Salts such as Sulphate of Zinc for the purpose.
specified.
Dated this twenty ninth day of May One thousand Eight hundred and Ninety
Seven.