Improvements in Culinary Vessels.
Year: 1896

page_text: Date of Application, 9th June, 1896-Accepted, 18th July, 1896
COMPLETE SPECIFICATION.
Improvements in Culinary Vessels.
I, ROMAINE CLARK COLE, of Waverly, in the County of Tioga and State of New
York, 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 object of my invention is to produce a culinary vessel which shall cook more
quickly without danger of scorching or burning the food than vessels at present in
use, and which shall also have its inner surface composed of a metal which is
incorrodible by any of the substances employed in cooking; and
consists in
forming the vessel of two layers of metal united in intimate contact, the inner
layer being an incorrodible metal of higher specific heat and higher thermal con-
ductivity than the metal employed for the outer layer of the vessel, and by being
employed in the form of sheet metal, instead of mere plating or coating, shall be
vastly more durable than any construction of vessel heretofore used for culinary
purposes.
Next after its healthfulness the chief desideratum of a culinary vessel is that it
shall be capable of cooking quickly and without danger of scorching or burning
the food. Many articles of food, as cereals, vegetables, fruit, milk, etc. are
exceedingly liable to scorch or burn in cooking, especially if allowed to
cook quickly, to avoid which result they are usually cooked in steamers, water-
baths, or vessels having double walls with a space between to be filled with
water, etc.
I have discovered that in order to enable a solid vessel to cook quickly, and at the
same time to prevent scorching or burning the food, the body wall of the vessel
must be of two or more laminæ or layers in immediate contact but of exactly
opposite physical characteristics as to their specific heat and thermal conductivity.
The outer layer which comes into contact with the fire .or source of heat, should
be of lower specific heat and lower thermal conductivity than the inner layer, for
the following reasons among others; when the outer layer is heated at a given spot
the corresponding and contiguous section of the inner layer requires a longer applica-
tion of the heat to raise it to the same temperature, and by virtue of its greater
thermal conductivity it distributes throughout its mass the heat received from the
outer layer. By the time therefore, that the inner and outer layers have attained
about the same temperature at the area exposed to the source of heat, the whole of the
outer layer has become heated and is giving up its heat to the inner layer at every
point. Thus, although the source of heat is at one spot, it cannot become sufficiently
concentrated or localized to produce burning of the contents of the vessel, as a portion
of the heat is continually being drawn away from the heated area of the outer layer,
by reason of its lower specific heat, and is imparted to the inner layer at all. points so
that by reason of the high thermal conductivity of the inner layer the contents of the
vessel cannot be scorched or burned until the whole mass of the inner layer is raised
to a heat sufficient to scorch, long before which time the cooking will have been
completed.
If the inner layer were not of higher specific heat than the outer layer the two
layers would attain the same temperature almost simultaneously and scorching would
aniably onene

page_text: I will now describe my invention so that others skilled in the art may manu-
facture the same.
In the accompanying drawing the figure represents a vertical sectional view of my
improved culinary vessel.
As a type of the metals of high specific heat and high thermal conductivity
which are suitable for use in carrying out my invention, silver and aluminum inay
be mentioned, and are preferable on account of being also practically incorrodible
by any of the substances ordinarily used as food, and on account of the fact that
any minute quantity of salts which might be formed, if any should be, would be
innocuous. If aluminum is to be used I proceed as follows:
Inasmuch as aluminum is softer and more ductile than iron, steel or other metal, of
lower specific heat and lower thermal conductivity which would be used for the
outer layer of the vessel, there is, unless a due proportion of thickness in the two
layers is preserved, a difficulty in drawing the two sheets at once without tearing
or drawing out of shape the aluminum lining. For this reason I prefer, in most
cases, to first draw the outer layer 2, of the vessel from sheet metal by means of
suitable dies in the usual manner. By means of similar dies I draw a blank from
a thin sheet of aluminum and place this blank within the vessel 2, and then subject
the two materials thus placed in contact with each other to a further drawing
operation, which causes the layers 2 and 3, to conform in shape with each other,
and causes a mechanical union between the two metals. To prevent separation of
the two layers from each other, the edges may be turned or curved so as to form
the bead 4, shown in the drawings. Instead of forming the blank from sheet
aluminum, I may insert the aluminum sheet in the partly drawn iron or other
shell and draw the metals together in the die or press. When; however, the steel
sheet is soft or annealed and not too thick sheets are employed, the two sheets
can readily be drawn together. In the case of a metal as hard as silver, which
also has a high thermal conductivity, the two sheets can be drawn together
without trouble, but as aluminum, although not the only metal embraced in my
invention, is the only one sufficiently cheap at the present time, to enable
employed for culinary vessels in competition with tin ware and other ware, I
.prefer to use it, and have described the method employed in forming vessels with
aluminum lining, it being understood that it is merely the best and not the only
metal applicable to the construction of culinary vessels employing the essence of
my invention, and that the same method of manufacture may be employed in
forming vessels with a lining or other incorrodible metals, of high specific heat
and high thermal conductivity.
to be
The advantages of vessels composed of an inner layer of incorrodible metal
which has high specific heat and high thermal conductivity are quicker cooking
without burning their contents and the impossibility of impregnating the food
with deleterious salts or compounds; greater durability; and their retaining
their heat longer; to realize which advantages it is important that the outer
layer should be of metal having lower specific heat and lower thermal conductivity
than the inner layer or lining, whence arises the choice of iron or steel for the outer
layer.
Having now particularly described and ascertained the nature of my inven
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. As a new article of manufacture, a culinary vessel formed of two layers of metal,
secured together in intimate contact, the outer layer being a metal of low specific
heat and low thermal conductivity, and the inner layer an incorrodible metal of high
thermal conductivity and high specific heat, substantially as described.
2. As a new article of manufacture, a culinary vessel formed of two layers of metal,
the outer layer being a metal of low thermal conductivity and low specific heat, as
iron or steel, and the inner layer an incorrodible metal of higher thermal conductivity

page_text: and higher specific heat, as silver or aluminum, the two metals being united in
intimate contact by pressure, substantially as described.
Dated this 9th day of June 1896.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.