IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD AND IN APPARATUS EMPLOYED THEREIN
Year: 1883

page_text: LETTERS PATENT to George Hand-Smith of N° 74 College Street Chelsea in
the County of Middlesex, Doctor of Medicine for an Invention of IMPROVE-
PROVISIONAL SPECIFICATION left by the said George Hand-Smith at
the Office of the Commissioners of Patents on the 26th December 1883.
GEORGE HAND-SMITH of N° 74 College Street Chelsea in the County of
Middlesex Doctor of Medicine "IMPROVEMENTS IN THE MANUFACTURE OF WHITE
LEAD AND IN APPARATUS EMPLOYED THEREIN
"
ر
This invention relates to improvements in the manufacture of white lead of
commerce by which I am enabled to effect a more efficient treatment of the
constituent elements by keeping them under better control and to effect their more
effectual combination with the aid of suitable apparatus adapted to facilitate such
chemical action with more rapid production of white lead of a good marketable
quality like in character to that produced by the well known Dutch or Anglo
Dutch process.
The object of the improvements is to obtain as nearly as may be those conditions,
most favorable to combination of the elements, conducive to the production of the
white lead which exist in the aforesaid Dutch process whilst avoiding or dispensing
with the employment of the objectionable and uncertain bark, spent tan or other
decomposing heap or stack of material employed in that process for generating the
moisture heat and carbonic acid employed in the reaction.
This I effect by conducting the improved operation on the lead in a suitable
chamber or vessel or chambers or vessels in which such lead in the "blue" or
metallic state with the other elements necessary to effecting the combination
desired are brought in contact and thereby effect the corrosion or decomposition of
that metallic lead which shall result in the production of the white lead.
In carrying out the improvements I take metallic lead which has previously
been perforated or formed into sheets with perforations or other suitable forms or
disintegrated in any suitable manner best adapted to facilitate superficial exposure,

page_text: of the metallic or blue lead to the action of the corrosive agents and this lead I
then arrange in layers or series permitting of free circulation of the gaseous and
vaporous elements throughout them so as to favor combination within a chamber
or vessel made of non-conducting materials or otherwise so constructed as to
prevent radiation or conduction away and consequent loss of heat from the same
as far as possible.
By constructing this chamber with non-conducting enclosing casing I am
enabled to maintain therein with greater certainty and economy any desired
temperature for a prolonged period.
Into this chamber or vessel so constructed and containing the metallic lead to be
treated arranged in suitable layers I introduce a mixture of air and carbonic acid
gas in suitable proportions relatively for effecting the desired corrosion or decom-
position of the lead.
This mixture of air and gas is before being introduced to the chamber containing
the lead first heated by any convenient means to a suitable temperature and then
passed next through a vessel which I call a saturator also heated and containing
and adapted to give off liquid to such mixture in the form of vapor and finally
this mixture of air and gas now charged or saturated with aqueous vapor and
acetic acid also provided in this chamber when required is conducted into the
operating chamber to act on the lead therein.
The temperature at which this operation may be effected can be varied within
a considerable range but I have had good results when employing a temperature of
from about 120° to 140° F.
If desired the acetic acid diluted with water may be introduced into the corroding
chambers by means of a tray or other suitable containing vessel.
Under these conditions white lead is produced but I find in practice that by first
supplying these gases thus saturated at a slight but definite pressure before
introduction into the lead operating chamber and then permitting them to expand
therein whereby those gases are more effectually saturated with moisture when
within the chamber or vessel in the presence of the lead, a greatly increased
chemical action is set up resulting in an increased production of white lead.
I employ any suitable method of production of carbonic acid gas such as by the
action of bydrochloric acid upon chalk or by the combustion of coke or of a mixture
of coke and chalk and subsequent purification or other well known agency may be
employed.
The resulting gas or mixture of gases mixed with the proper proportion of air
may be stored in a suitable reservoir or gasometer and then supplied to and caused
to pass through a suitable saturator kept at a heat of a desired temperature so as
to cause such gaseous mixture to become saturated or charged with moisture from
liquid contained in that saturator consisting of water or water and acetic acid.
Pumps or other suitable forcing means may be employed to cause the flow of the
gaseous mixture through the apparatus and pressure and heat may be given to the
Baid gases in the saturator and to be maintained until the same is permitted to
enter the lead containing chamber by means of suitable conduits. The moisture
laden gaseous mixture on entering the operating chamber becomes released from
pressure inducing a condition of such atmosphere most favorable to the production
of the white lead.
One form of saturator which I employ consists of a shallow oblong closed box or
chamber of copper or other suitable material adapted to resist corrosion provided
with inlet and outlet pipes at opposite ends or so arranged as to ensure the fullest
possible saturating action of the moisture from the contained water or water and
acetic acid the dispersion thereof into the passing air and gas being aided by a
series of diaphragms or sheets of porous material such as cotton cloth or other
suitable substance adapted to hold suspended the liquid whilst offering little
resistance to the flow of the gaseous fluid through them in a heated state favorable
to such absorbtion.

page_text: Steam may be employed for the saturation of the gases but care should be taken
to prevent the admission into the lead containing chamber of excessive condensed
moisture to the detriment of satisfactory action.
The lead-containing chamber I form of metal or other suitable material capable
of being heated to and maintained at the same temperature as that of the gases
issuing from the saturator and conveyed to such lead chamber.
Radiation or loss of heat from these chambers where the operation upon the lead
and also those employed for effecting the saturation may be prevented or the heat
therein may be efficiently controlled by enclosing those chambers with other
surrounding walls or with intervening cells or spaces so that air or gaseous fluid or
vapor heated to the desired temperature may be supplied to and retained in them.
According to another modification I employ chambers or vessels made of non-
conducting materials such as wood or wood and felt or other heat retaining
medium.
The heat for the lead containing chamber may be obtained by the passage there-
through of heated gases or this heat may be supplied by means of a water bath
deriving its heat in turn from gas jets or other source of heat or the heat from the
passing gases in that chamber may be supplemented by the aid of steam pipes or
hot air tubes or other suitable means.
The time of treatment required will necessarily depend upon the thickness or
relative surface exposed of a given quantity of lead operated upon and the strength
of the acetic acid solution may also vary somewhat but I have obtained good
results when using acetic acid in the saturator mixed with water in the proportion
of 0.75 per cent of acetic acid but when used in the lead operating chamber the
strength of that solution may be somewhat greater.
The air and the carbonic acid gas employed may be saturated separately with
the required vapor and acetic acid and then allowed to mix in the operating
chamber or corroding vessel.
When preferred dilute nitric acid may be employed instead of acetic acid or
dilute nitric acid mixed with acetic acid may be so employed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Hand-Smith in the Patent Office on the 26th June 1884.
GEORGE HAND-SMITH of N° 74 College Street Chelsea in the County of
Middlesex Doctor of Medicine "IMPROVEMENTS IN THE MANUFACTURE OF WHITE
LEAD AND IN APPARATUS EMPLOYED THEREIN
"
This invention relates to improvements in the manufacture of white lead of
Commerce by which I am enabled to effect a more efficient treatment of the
constituent elements employed in the manufacture by keeping them under better
control and I ensure their more effectual combination with the aid of suitable
apparatus which is adapted to facilitate chemical action and effect the production
of white lead of a good marketable quality in much less time than is required by
the ordinary processes hitherto in use.
The object of the improvements is to operate upon the elements employed in
producing white lead under those conditions which as hereafter explained are most
favorable to their combination and which result in a successful and rapid production
of white lead such as is produced by the well known Dutch or Anglo Dutch
process and at the same time avoid or dispense with the employment of the
objectionable and uncertain bark, spent tan or other decomposing material usually
employed in that process for generating the moisture heat and carbonic acid
employed in the reaction
I effect my object by conducting the improved operation on the lead in a
suitable jacketed chamber or vessel or vessels in which such lead in the blue or
metallic state and in a suitable perforated, granulated, or otherwise disintegrated
condition is placed with the other elements necessary to effect the combination
desired and I thereby effect a rapid corrosion of that metallic lead and cause it to
be so acted upon as to produce a good quality of white lead.
I place the prepared blue lead in or upon shelves or frames arranged in the
jacketed chamber or vessel which may be made of non-conducting materials or a
chamber or vessel surrounded by an air jacket or casing or otherwise so constructed
as to prevent radiation or conduction away and consequent loss of heat from the
same as far as possible.
By constructing this chamber with non-conducting enclosing casing I am enabled
to maintain therein with greater certainty and economy the temperature found
necessary for a prolonged period
Into this chamber or vessel so constructed and containing the metallic lead to be
treated arranged as aforesaid in suitable layers I introduce a mixture of air and
carbonic acid gas so as to operate in the manner well known upon the lead
This mixture of air and gas is before being introduced to the chamber containing
the lead first heated by any convenient means to a suitable temperature it is then
passed through a vessel which I call a saturator which is also heated and contains
water or water mixed with acetic acid which is taken up by the mixture of air
and gas in the form of vapor. The mixture of air and gas and vapor is thus charged
or saturated with aqueous vapor and when necessary with acetic acid and is
conducted into the operating chamber to act on the lead therein
The proportion of acetic acid taken up is relatively small
The temperature at which the operation may be effected can be varied within a
considerable range but I have had good results when employing a temperature of
from about 120° to 140° Fah.
To further ensure sufficiently the supply of acetic acid vapor it is found
convenient sometimes to introduce into the corroding chambers by means of a tray
or other suitable containing vessel a further supply of acetic acid

page_text: I have ascertained that the required conversion of metallic lead into white lead
is much facilitated and accelerated by first supplying the gases saturated as above
described at a slight but definite pressure as hereinafter mentioned before their
introduction into the operating chamber and on their being thus allowed to expand
therein an active chemical action is set up within the operating chamber resulting
in a large and rapid production of white lead. I employ any suitable method for
producing the carbonic acid gas required such as by the action of hydrochloric acid
upon chalk or by the combustion of coke or of a mixture of coke and chalk and
subsequent purification or other well known agency may be employed
The resulting gas or mixture of gases mixed with the proper proportion of air
may be stored in a suitable reservoir or gasometer and then be supplied to and
caused to pass through a suitable heated saturator such as is above referred to so
as to cause such gaseous mixture to become saturated or charged with moisture from
liquid contained in that saturator consisting of water or water and acetic acid.
Pumps or other suitable forcing means may be employed to cause the flow of the
gaseous mixture through the apparatus
A form of saturator which I find may be used with advantage consists of a
shallow oblong closed box or chamber of copper or other suitable material adapted to
resist corrosion provided with inlet and outlet pipes at opposite ends or so arranged
as to ensure the fullest possible saturating action of the vapor given off by the
contained water or water and acetic acid the dispersion thereof into the passing air
and gas being aided by a series of diaphragms or sheets of porous material such as
cotton cloth or other suitable substance adapted to hold suspended the liquid whilst
offering little resistance to the flow of the gaseous fluid through them in a heated
state favorable to such absorption
Instead of a single long chamber a series of saturating chambers connected by
suitable pipes and provided with regulating cocks may be employed the construction
of such chambers being of the kind ordinarily known.
The lead containing chamber I form of metal or other suitable material capable
of being heated to and maintained at the same temperature as that of the gases
after expansion in such lead chamber.
Radiation or loss of heat from these chambers where the operation upon the lead
and also those employed for effecting the saturation may be prevented or the heat
therein may be efficiently controlled by enclosing those chambers with other
surrounding walls or hollow casing or with intervening cells or spaces so that air or
gaseous fluid or vapor heated to the desired temperature may be supplied to and
retained in them
Instead of employing metallic chambers or vessels made of nonconducting
materials such as wood or wood and felt or other heat retaining media may be
used
The heat for the lead containing chamber may be obtained by the passage
therethrough of heated gases or this heat may be supported by means of a water-
bath deriving its heat in turn from gas jets or other source of heat or the heat from
the passing gases in that chamber may be supplemented by the aid of steam pipes
or hot air tubes or other suitable means
The time of treatment required will necessarily depend upon the thickness or
relative surface exposed of a given quantity of lead operated upon. The strength
of the acetic acid solution may also as is well known vary within reasonable limits
but I have obtained good results when using acetic acid in the saturator mixed
with water in the proportion of 0.75 per cent of acetic acid but when used in the
lead operating chamber the strength of that solution may be somewhat greater
The air and the carbonic acid gas employed may be saturated separately with
the required vapor and acetic acid and then allowed to mix in the operating
chamber or corroding vessel
When preferred dilute nitric acid may he employed instead of acetic acid or
dilute nitric acid mixed with acetic acid may be so employed
In order more fully to explain my improved process of manufacturing white lead

page_text: I will now proceed to describe the same with reference to drawings illustrating the
forms of apparatus which I find it advantageous to use
Figure 1. shews a longitudinal section of one form of the apparatus which I
employ with advantage. Figure 2 is a transverse section of the same and Figure 3
is a sectional plan view thereof.
a indicates the chamber where the lead in a metallic state is placed to be
operated upon by corrosion to form the white lead of commerce and this chamber a
is accessible by openings or doors at a' b c in the walls of that chamber and of the
surrounding heat retaining air cells be; d, is a saturator supplying air saturated
with moisture to the chamber a by a pipe d¹ which pipe has a contracted orifice
within the chamber a
This saturator d is provided with a series of porous or perforated diaphragms
shewn by dotted lines d³ at intervals therein which hold suspended a mixture of
water and acetic acid placed therein and giving off the same to air and gases
traversing that saturator d in their course to the chamber a under pressure and
this mixture of air and gases is heated prior to its entering the saturator d by its
traversing the serpentine pipe d³ in its passage from a suitable source of air and
carbonic acid gas supply under pressure, such as a pump, bellows, or gasometer
chamber
The chamber a is supported above the level of a tray or channel for liquid
formed by the lower parts of the heat retaining cells bc at b¹ throughout which
the contained liquid may circulate and within this liquid the saturator d is placed
for the purpose of being heated. Beneath this tray 61 is formed the water bath h
for conveying equably to the whole apparatus the heat supplied by the gas
burners e. is a supply pipe and h² a draw off to the bath h and 62 63 are like
pipes to the inner liquid receptacle b¹. f is a pipe for the escape of surplus
atmosphere from the lead chamber a. g is a thermometer for indicating the
temperature of that chamber and a like indicator is applied to the water bath /
but is not shewn. Valves and regulators and indicators are also applied to the
gas supply pipes to the burners e in manner well understood and not necessary to
shew in the drawing"
Another form of apparatus is illustrated at Figure 4 by a vertical section, only
such details as are of ordinary and well known construction and used in manner
common with such details or subsidiary appliances being omitted to avoid compli-
cation of the drawings. Figure 5 is a horizontal section of the apparatus shewn
by Figure 4. Similar letters refer to similar parts in such of these views as in the
preceding figures so far as the parts are alike
The metallic lead suitably perforated or disintegrated is placed as in the previous
arrangement in the operating receptacle a through doors b c d which respectively
are formed in the walls of the chambers or surrounding heat retaining cells b and c
which cells surround and retain heat to the receptacle a on all sides except the
bottom thereof
The chamber or receptacle a may be formed of copper, galvanized iron, or other
material adapted to the purpose-Within these cells b and c is retained air, or gas,
with moisture or vapor, so that uniformity of heat to the receptacle a is maintained
during the operation. Beneath the chamber or receptacle a is a water bath h
which bath is heated by a series of gas jets e¹ supplied by pipes e and these pipes
are provided with suitable valves and pressure regulators and indicators of the
ordinary and well known construction and therefore not necessary to be shewn.
The water bath h is provided with a thermometer j to indicate the variations of
temperature and g is a thermometer to indicate the temperature of the lead
operating chamber a. d' is a pipe having its point of delivery formed as a small
contracted outlet or orifice within the chamber a and this pipe d¹ serves to deliver
gaseous and vaporous elements therein to act on the metallic or blue lead in
suitable disintegrated form arranged therein and these gases and vapors are
delivered therein under pressure and expansion ensues as such delivery takes place
producing in the chamber a the proper condition of atmosphere for the desired

page_text: operation on the lead. f is an outlet pipe for the exit of any surplus gases or air
from the chamber.
The arrows indicate direction of flow of fluid
I do not confine myself to the particular forms of apparatus for saturating the air
or gases with the vaporous elements but I have found that such saturation can be
more conveniently and efficiently effected by means of the saturating vessels d
being arranged separately from the operating chamber as shewn by the modification
in these Figures 4 and 5 in which d¹ the connecting supply pipe is carried through
a surrounding or covering pipe for retaining heat k from the operating apparatus to
the saturating portion and the pipe d₁ communicates with the saturator
chambers d d d. The air to be saturated with moisture enters the chambers
Nos 3. 2. 1. in turn from a pipe n which receives its supply from any suitable
pump or other suitable source of supply or reservoir n¹ are pipes connecting the
vessels dd d
The water bath s encases the saturator d and the connecting and supply pipes d',
n, and n¹, and this bath is heated by other gas jets supplied by pipes . The
curtains 8 to these burners and the like curtains to the burners e¹ serve to detain
the heated air. 62 is a pipe of supply to b¹ and h¹ is a pipe of supply and h³ the
draw off of liquid to and from h―The pipe n takes a convoluted or serpentine
course through the water baths before entering the saturator chambers d
No 3.21 in succession in order to warm the air and thereby increase its capability
of saturation or absorption
The dotted lines in the saturator chambers d indicate a series of veils porous
diaphragms or porous surfaces of absorbent material such as cotton cloth adapted
to draw up moisture supplied to such chambers d and again deliver moisture to
the current of air passing through them and saturate it o is a gauge or indicator
of pressure within these chambers d-p is a thermometer to the water bath. 8² is
a pipe of supply and the draw off of liquid to and from the water bath s
Other suitable well known means of heating may be employed in lieu of gas as
may be found convenient to heat the chambers by means of the water baths
The curved roofs to the chamber a and heat retaining cells b and c serve to
carry down any moisture which might condense thereon and to prevent collection
thereof on those roofs.
The arrows shew the direction of flow of the air through the saturator and
heater to the lead chamber a. The equable distribution of the prepared air gas
and vapor within the chainber a may be aided by revolving or other suitable
distributing apparatus and this may be applied to the pipe d' within the chamber a
so as to distribute the air and vaporous current throughout such chamber. The
tubes or legs of this distributor may be formed in pairs, one of each pair projecting
on either side the length of each pair being different or the legs may be so bent as
to distribute from each pair at a different distance from the centre or inlet
The operation as carried on with this apparatus is as follows, the prepared
metallic lead in a suitably reduced or disintegrated condition is as already
mentioned placed in the chamber a, that chamber is closed and then heated to
about 120° to 140 Fah. say for instance to 120° and then the cock controlling
the pipe is turned permitting the inflow of the corroding moisture-laden air
from the saturator at a temperature of say 129° and this air under a pressure
of (say for instance) six inches of water in column on entering the chamber a
expands and the temperature of this atmosphere becomes about 120° Fah, in the
operating chamber whilst the gaseous air is most effectually saturated with
moisture in the presence of the lead and a most efficient chemical action is set up
resulting in a rapid production of white lead of excellent quality-A proportion of
carbonic acid gas to the air which has been found to give most advantageous results
is about 20 per cent of carbonic acid gas to about 80 per cent of air
The carbonic acid gas as above stated may be generated by any of the well
known modes in use and be supplied to the pipe d².

page_text: Having thus described the nature of my invention and, means adapted for
carrying the same into practical effect I would have it understood. that
What I claim is
1. The process of manufacturing white lead from metallic or blue lead by
submitting metallic lead within a suitable chamber to the corroding action of acid
vapors and air prepared in a saturating chamber such as is above referred to and
introduced under pressure into and allowed to expand within such chamber
substantially as described.
2. The use in the manufacture of white lead by my improved process of apparatus
such as is above referred to substantially as described and shewn.
In witness whereof I the said George Hand-Smith have hereunto set my hand
and seal this twenty third day of June in the year of our Lord One thousand eight
hundred and eighty four:
Witness:
ALFRED GEORGE BROOKES.
55 Chancery Lane London
Patent Agent
GEORGE HAND-SMITH: (L.S.)
(