Year: 1887

page_text: Date of Application, 23rd Sept., 1887
Complete Specification Left, 23rd June, 1888
Complete Specification Accepted, 14th Sept., 1888
Republic of France.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, in the County of Lancaster, and 323, High
Holborn, in the County of Middlesex, Civil Engineer, do hereby declare the nature
of this invention to be as follows:-
Hitherto the hardening operations have been made in the mass of a liquid body at
the initial temperature of the operation, either naturally or by a previous liquefaction
under the influence of heat, for instance. Under these conditions the cooling of the
hardened body was solely a function of the conductivity and calorific capacity of the
medium within which the operation was taking place.
The present invention is based upon the intervention and utilization in hardening
operations, of the latent heat of fusion of the bodies used as hardening media, and
more especially of certain bodies mentioned hereafter.
In other words, the cooling of the body to be hardened, is effected, and the rapidity
and efficacy of the operation increased, by the absorption of the whole or part of the
superfluous heat, through the melting of the whole or part of the hardening medium,
the temperature of which will remain sensibly constant so long as the fusion has not
become total, or will vary between limits determined according to the circumstances
of the case.
The possibility of keeping constant the temperature of the hardening
medium insures the rapidity of the operation and the obtaining of intense results
from the point of view of the phenomena of the hardening process, when this is
needed.
The hardening media we use vary according to the results desired to be obtained,
that is to say, according to the degree of hardness desired to be given, and to the
nature of the objects to be hardened.

page_text: The following are preferably employed:
1st. A saline bath mixed with ice or a refrigerating mixture.
2nd. A water bath, preferably saline, mixed with ice or a refrigerating mixture.
In both cases the ice can be introduced into the hardening bath, or constituted and
reconstituted in the bath by means of refrigerating machinery.
3rd. A bath of nitrate of soda, a salt fusible in its water of crystallisation. This
medium is more especially suitable for soft hardening at high temperatures; its action
is regulated by adding or withdrawing crystallization water, or by adding during the
course of the operation, hydrated or anhydrous salt.
4th. A solid and fusible medium in contact with the piece to harden; pressure
being used if necessary to ensure the contact, this medium being constituted by ice,
solid nitrate of soda, or a metal or alloy having a low melting point, lead for
instance.
According to circumstances, the body to be hardened is introduced and kept under
pressure in the solid hardening medium, or in a cell or free space provided therefor in
the solid medium; or lastly it is introduced in the tank or apparatus intended for
hardening, into which a sufficient quantity of the solid hardening body in the form of
pieces or fragments of suitable size is thrown, such as ice, salt, or metal.
In some cases the hardening action is continued by adding in the tank, fragments
of the hardening body, as the first ones melt.
Whatever mode of hardening amongst the above is used, the hardened body can,
according to the results required, be withdrawn from the liquid or solid bath, either
before or after its complete cooling:
Dated this 22nd day of September 1887.
WM. P. THOMPSON & Co.,
Agents for the Applicant.

page_text: I, WILLIAM PHILLIPS THOMPSON, F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, in the County of Lancaster, and 323 High
Holborn, in the County of Middlesex, Civil Engineer, 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 :-
The invention relates to hardening steel and homogeneous metal (iron, mild steel
and extra mild welding steel) and ingot steel applicable more particularly to the
manufacture of projectiles for guns, armour plates for ships, or fortifications of all
sorts, plates and sheets for ship decks, hulls, decks, bridges, turrets, and other parts
of torpedo boats, gun boats, ships' boats and shore boats, as well as gun carriage
screens (masques) and all other applications of a similar nature.
Hitherto, hardening operations have been effected in the mass of a liquid body at
the initial temperature of the operation either naturally, or by a previous liquefaction
under the influence of heat. Under these conditions, the cooling of the hardened
body was solely a function of the conductivity and calorific capacity of the medium
in which the operation was taking place.
The present invention is based upon the intervention and utilization in hardening
operations, of the latent heat of fusion of the bodies used as hardening media, and
more especially of certain bodies mentioned hereafter.
In other words, the cooling of the body to be hardened is effected, and the rapidity
and efficacy of the operation increased by the absorption of the whole or part of the
superfluous beat through the melting of the whole or part of the hardening medium,
the temperature of which will remain sensibly constant so long as the fusion has not
become total, or will vary between limits determined according to the circumstances
of the case. The possibility of keeping constant the temperature of the hardening
medium insures the rapidity of the operation, and the obtaining of intense results
from the point of view of the phenomena of hardening process, when this is
needed.
The hardening media used, vary according to the results desired to be obtained, that
s to say, according to the degree of hardness desired to be given, and to the nature
of the objects to be hardened.
The following are preferably employed:
1st. A saline bath mixed with ice or a refrigerating mixture.
2nd A water hath preferably saline mixed with ice or a refrigerating mixture.

page_text: In both cases, the ice can be introduced into the hardening bath, or constituted and
reconstituted in the bath by means of refrigerating machinery.
3rd. A bath of nitrate of soda. This medium is more especially suitable for soft
hardening at high temperatures; its action is regulated either by adding or with-
drawing water, or by adding during the operation, either hydrated or anhydrous salt.
4th. A solid medium fusible in contact with the piece to be hardened, pressure
being used, if necessary, to insure the contact, this medium being constituted by
ice, solid nitrate of soda, or a metal or alloy having a low melting point, lead for
instance.
According to circumstances, the body to be hardened may be introduced and kept
under pressure in the solid hardening medium, or in a cell or free space provided
therefor in the solid medium, or lastly, it is introduced in the tank or apparatus
wherein the hardening is effected, into which is thrown a sufficient quantity of the
solid hardening medium in the form of pieces or fragments of suitable size, such as
ice, salt or metal.
In some cases the hardening action is continued by adding in the tank, fragments
of the hardening body in proportion as the first ones melt.
Whichever mode of hardening is adopted, the hardened body can, according to the
results required, be withdrawn from the liquid or solid bath, either before or after its
complete cooling.
Having now particularly described and ascertained the nature of the said invention,
and in what manner the same is to be performed, as communicated to me by my
foreign correspondents, I declare that what I claim is :-
1st. In the hardening of steel and other metals having similar hardening properties,
the application of the absorption of the latent heat of fusion, substantially as
described.
2nd. The application, for the purposes above described, of ice or other suitable
solid soluble bodies in saline solutions, or of saline solutions in water or other
solvent, or of solid bodies fusing at low temperature, or in their own water of
crystallisation.
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