IMPROVED APPARATUS FOR CONCENTRATING ACIDS
Year: 1879

page_text: LETTERS PATENT to Henry Edward Newton, of the Office for Patents, 66,
Chancery Lane, in the County of Middlesex, Civil Engineer, for the Invention
of "IMPROVED APPARATUS FOR CONCENTRATING ACIDS." A communication
from abroad by Alfred Nobel, of Paris, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said Henry Edward Newton at
the Office of the Commissioners of Patents on the 10th October 1879.
HENRY EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer. "IMPROVED APPARATUS FOR CONCEN-
TRATING ACIDS." [A communication from abroad by Alfred Nobel, of Paris, in
the Republic of France.]
Hitherto the only metal for forming vessels in which acids, especially sulphuric,
could conveniently be brought to a high degree of concentration was platinum.
Cheaper metals could not be used from their liability to rapid corrosion by the
acids.
The present Invention relates to the construction of apparatus whereby the use
of the cheaper metals such as iron for the aforesaid purpose is rendered practicable.
Experiment has shown that metals which are rapidly corroded by the direct action
of fluid acids are nevertheless well able to resist the action of the fumes of such
acids, and it is upon this fact that the present Invention is based.
The apparatus in its simplest form is constructed as follows:-
Into a wide cast iron tube placed vertically in a stove or furnace is inserted a
column built up of fragments of earthenware, so as to leave a free space between
them. The iron tube and the stoneware column rest on a sandstone or stoneware
base to which they are fixed by fireclay, cement, or otherwise. This base is
slightly hollowed to form a shallow receiver, the upper part of the column ends in
a cone immediately over which terminates a small tube connected with a tank
containing the acid which it is intended to concentrate. The cast iron tube which
serves as a retort is furnished with an iron lid through which the inlet tube for the
acid passes.
The apparatus works as follows:—
On lighting the fire in the furnace the flames play around the cast iron tube or

page_text: retort, and the column is thus heated. On letting in liquid acid through the small
tube it flows over the stoneware column and becoming heated gives off vapours or
fumes, the temperature of which being further raised by exposure to the heat of
the retort, assist while, remaining in the retort in the generation of vapours or
fumes from the further supply of the weak liquid acid.
The degree of concentrations required determines the rate of supply of the weak
acid. The acid flowing down the column accumulates in the receiver at the base
as concentrated acid, and is drawn off through a small platinum tube inserted for
that purpose. The acid fumes which distil are led through another outlet into a
special condenser which does not differ from those now in use.
The column herein described may be replaced by a vertical range of earthenware
plates or vases, so arranged that the acid by degrees as it accumulates flows from
one to the other. But whatever may be the arrangement of details, the main
feature remains the same, viz., the liquid acid to be concentrated is never allowed
to touch the metal of which the retort is formed, but only the vapour or fumes of
such acid.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Henry Edward Newton in the Great Seal Patent Office on the 9th April
1880.
HENRY EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer. "IMPROVED APPARATUS FOR CONCEN-
TRATING ACIDS." A communication from abroad by Alfred Nobel, of Paris, in the
Republic of France.
Hitherto the only metal for forming vessels in which acids, especially sulphuric,
could conveniently be brought to a high degree of concentration was platinum.
Cheaper metals could not be practically employed from their liability to rapid
corrosion by the acids, and the use of glass retorts was objectionable because of
their liability to break and their want of heat conducting power.
The present Invention relates to the construction of apparatus, whereby the use
of the cheaper metals such as iron for the aforesaid purpose is rendered practicable.
Experiment has shown that metals which are rapidly corroded by the direct action
of fluid acids are nevertheless well able to resist the action of the fumes of such
acids, and it is upon this fact that the present Invention is based.
To this end a tower constructed of tubes of cast iron is built up within a furnace,
and into this tower is admitted the weak acid intended to be concentrated. The
acid as it falls from the top of the tower will flow over intorcepting surfaces of
earthenware or glass with which the tower is fitted, and these being heated by
the flame of the surrounding furnace, the acid descending to the base of the tower
will be partially vaporized and proportionately concentrated. The form of apparatus
employed for this purpose admits of considerable variation, but the arrangement
which has been found to answer well I will now proceed to describe.

page_text: In the accompanying Drawing Fig. 1 shews in sectional elevation the improved
apparatus for concentrating acids taken on the line W, W, of Fig. 2, which is a
sectional plan view of the same taken on the line X, X, of Fig. 1; Figures 3 and 4
shew on an enlarged scale details of the construction of the concentrating tower or
chamber, Fig. 3 being a partial vertical section of the chamber, and Fig. 4 a cross
section on the line Y, Y, of Fig. 3; Fig. 5 is a partial sectional elevation of the
apparatus taken at right angles to Fig. 1, and Fig. 6 is a partial front elevation of
the apparatus.
A, A, is the tower or concentrating chamber consisting of the several lengths of
socketted pipes of cast iron a, a, a, a, set one upon the other, the joints being mado
tight with asbestos or other suitable material capable of resisting the corrosive
action of acid fumes.
The tower or concentrating chamber is closed at top by a cover a¹ which is
furnished with a hole through which the acid to be treated is supplied to the
concentrating chamber.
This tower is set up in a furnace B which is provided with a cylindrical
chamber C for the reception of the tower in communication with the fire place D.
The base of the tower rests upon the bottom of the chamber C, but the pipes of
which the tower is composed are also supported by means of projections from the
brickwork of the chamber. This chamber is closed by a plate E, and it is brought
into communication by means of the flue F with an adjacent chimney for carrying
off the gases of combustion from the furnace. The pipes a, a, a, are cast with
projections b, b, b, b, b, b, on their inner periphery for supporting trays c, c, c, c, c, c,
made of porcelain, fire-clay, glass, tempered glass, or equivalent material that will
resist the corrosive action of the acids which are to be concentrated. The acid to
be treated is conveyed from a tank through the cock e into a funnel f inserted in
the hole in the cover a', and from whence it passes into the concentrating tower.
The trays c, c, are provided with overflow holes g, g, through which the acid
passes to the tray beneath. In order to prevent splashing, small glass or porcelain
tubes or cylinders h, h, h, h, are inserted in these holes and allowed to rest on the
tray beneath. The over flow liquid will therefore spread over the surface of these
loosely fitting cylinders h and trickle down them into the tray on which they rest;
i is a small platinum tube connected with the lowest tray c, and through which
the fully concentrated acid escapes into a cooling worm of the usual form and
construction; is a pipe of cast iron connected with the lowest section of the
tower, and through it the acid fumes given off in the course of concentration mako
their escape into a condenser of any approved construction. This pipe is kept
hot to prevent the condensation of the acid fumes therein as they pass off to the
condenser, and the joint between the pipe k and the tower A is also made tight
with asbestos or other suitable material.
The form of the trays c, c, and the manner in which they are arranged in the
chamber A so as to provide a zigzag course for the passage downwards of the
fumes and vapour is clearly shewn in the enlarged views, Figures 3 and 4, the
trays being made circular with a portion of their periphery cut away to leave a
passage for the fumes.
Figures 5 and 6 indicate the position of the fireplace which presents no peculiar
feature needing special description. It will be observed that the frame acts
directly on the cast iron tower or chamber A in which an atmosphere of high
temperature is consequently maintained.
The action of the apparatus is as follows, viz., the acid to be treated is first
allowed to flow from a supply tank through the tap e and funnel ƒ into the
tower A until all the trays c, c, in the tower are full. This will be indicated by the
escape of acid through the small platinum tube i. Upon the fire being lighted
the walls of the chamber A will become heated, and the heat radiating from the
walls will act upon the acid contained in the trays c, c, and cause it to give off
vapours and fumes. These vapours as they pass downwards in a zig zag course
(consequent upon the peculiar form and arrangement of the trays) to the pipe k,

page_text: will come alternately in contact with the sides of the tower A from which they
will take up heat, and with the acid in the trays c, c, to which they will impart
the heat just taken up. The acid becomes more and more concentrated as it
descends, and the tape is so regulated as to admit only the quantity of acid
requisite in order to obtain its full concentration when it escapes through the tube i.
The pipe k through which the acid fumes escape may be adapted to any part of
the tower A, but it is preferred to place it in the position shewn in the Drawing,
viz., at the bottom of the tower as offering thereby the greatest guarantee against
eventual condensation of the acid fumes on the metallic surface which would
thereby be corroded. Since the heat which raises the temperature of the acid is
derived from the sides of the tower A, it is evident that the temperature of the
metal will always be somewhat higher than that of the acid, so that no conden-
sation of acid fumes against the metallic surface can take place.
When nitric acid is being concentrated it is better to replace the small platinum
tube i by a small glass or porcelain tube.
It will be evident that the construction of the tower or apparatus as herein
described may be greatly varied without departing from the principle of the
Invention, the sole object of which is to prevent the corrosive action of sulphuric
and nitric acids on iron, cast iron, and other metals which those acids in their
liquid form attack.
Having now described the nature of this Invention for "Improved Apparatus for
Concentrating Acids," as communicated to me by my foreign correspondent, and
explained the manner of carrying the same into effect, I wish it to be understood
that under the above in part recited Letters Patent I claim,-
First. The apparatus, substantially as herein described, for the purpose of con-
centrating sulphuric and nitric acid as well as any fluids acting corrosively on
iron and common metals, but which are comparatively innoxious when in a state
of vapour.
Second Constructing apparatus for concentrating acids on the principle above
described, whereby the use of platinum to form the concentrating chamber is
rendered unnecessary, and a cheap metal such as cast iron may be substituted
therefor.
In witness whereof, I, the said Henry Edward Newton, have hereunto set my
hand and seal, the Ninth day of April, in the year of our Lord One thousand
eight hundred and eighty.
H. E. NEWTON. (L.S.)