IMPROVE- MENTS IN RECOVERING SURPLUS INDIGO FROM TEXTILE MATERIALS OR FABRICS
Year: 1875

page_text: LETTERS PATENT to John Auchinvole, of Glasgow, in the County of
Lanark, North Britain, Merchant, for the Invention of "IMPROVE-
MENTS IN RECOVERING SURPLUS INDIGO FROM TEXTILE MATERIALS OR
FABRICS."-A, communication from abroad by Camille Bouhon,
residing at Ensival, in Belgium.
PROVISIONAL SPECIFICATION left by the said John Auchinvole at the
Office of the Commissioners of Patents, with his Petition, on the
31st July 1875.
56
I, JOHN AUCHINVOLE, of Glasgow, in the County of Lanark, North
3 Britain, Merchant, do hereby declare the nature of the said Invention
for IMPROVEMENTS IN RECOVERING SURPLUS INDIGO FROM TEXTILE MATERIALS OR
FABRICS," (a communication to me from abroad by Camille Bouhon,
residing at Ensival, in Belgium,) to be as follows, that is to say :-
This Invention has for its object the recovering of a considerable per-
centage of the indigo employed in dyeing textile materials or fabrics,
and which has heretofore been generally wasted

page_text: In carrying out the Invention the dyed goods with the blue color
developed upon them are washed in water in which soda crystals are
dissolved, and the water is by preference well drained from them, or it is
expressed by passing the goods through rollers on leaving the washing
tank. To the wash water there is then added a further quantity of soda
crystals, and after these are dissolved a quantity of hydrochloric or
other suitable acid is thoroughly mixed in. The carbonic acid gas dis-
engaged from the soda by the acid carries up to the surface most of the
indigo contained in the wash water, and this indigo may be skimmed
off and be drained by sioves or filters A further quantity of indigo
is recoverable on allowing the skimmed water to rest when the indigo,
still in suspension, gradually subsides to the bottom of the tank, and
may be removed after drawing off the supernatant clear water
The proportions of the ingredients used may be varied, but good
results are obtainable with the following .-For every 100 lbs. (of wool,
for example) about 6 oz of soda crystals are dissolved in the water in
which the wool is washed, and after the wool is withdrawn about 7 lbs.
more of the soda crystals are added, afterwards about 28 lbs. com-
mercial hydrochloric acid are mixed in.
Any suitable or sufficiently economical carbonate may be substituted
for the soda crystals, and any suitable or sufficiently economical acid
may be used instead of hydrochloric acid. Or instead of the indigo
being acted upon by carbonic acid gas, as described, air or any inert gas
may be blown through the wash water, being introduced under a fincly
perforated bottom or plate so as to permeate the water in fine streams
or particles.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said John Auchinvole in the Great Seal Patent Office
on the 31st January 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN 3
AUCHINVOLE, of Glasgow, in the County of Lanark, North Britain,
Movehant sond erecting.

page_text: year of our Lord One thousand cight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Auchinvole, Her special
licence that I, the said John Auchinvole, my exccutors, administrators,
and assigns, or such others as I, the said John Auchinvole, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
RECOVERING SULPLUS INDIGO FROM TEXTILE MATERIALS OR FABRICS," the same
being a communication to me from abroad by Camille Bouhon, residing
at Ensival, in Belgium, upon the condition (amongst others) that I,
the said John Auchinvole, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Scal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said John Auchinvole, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly 'described and ascertained in and by
the following statement in writing, that is to say :-
The said Invention has for its object the recovering of a considerable
percentage of the indigo employed in dyeing textile materials or fabrics,
and which has hitherto been generally wasted.
In carrying out the Invention in practice the dyed goods with the
blue color developed upon them are washed in water in which soda
crystals are dissolved, and after the washing has been continued long
enough the water is well dramed from them, or it is expressed from
them by means of rollers between which they are passed on leaving the
washing tank. To the water there is then added a further quantity of
soda crystals, and after these are dissolved a quantity of hydrochloric
or other suitable acid is thoroughly mixed in The acid causes a strong
effervescence and disengagement of carbonic acid gas from the soda,
and this gas carries up to the surface of the liquid a large part of the
indigo contained therein. The indigo thus thrown up may be separated

page_text: A
by skimming and may be drained by means of sieves or filters
further quantity of indigo is recoverable on allowing the skimmed
water to rest, when the indigo still in suspension gradually subsides to
the bottom of the tank and may be removed after drawing off the super-
natant clear water.
And in order that the said Invention and the manner of performing
the same may be properly understood, I will now particularly state the
proportions of ingredients and details of process which I believe proper
for obtaining the best results in ordinary cases, promising however that
the proportions and details may be more or less varied in practice
according to the circumstances of each case. For every 100 pounds (of
wool, for example) about 6 ounces of soda crystals (ordinary mono-
carbonate of soda) are dissolved in the water in which the wool is to bo
washed, and after the wool is washed and withdrawn about 7 pounds
moro of the soda crystals are to be added to and dissolved in the water,
afterwards about 28 pounds commercial hydrochloric acid arc to be
mixed m.
In some cases it is preferable to use sulphuric instead of hydrochloric
acid, but whatever be the acid used the quantity of it should be such
as to neutralise the soda or to render the liquid slightly acid. The indigo
rising to the surface is to be skimmed off or otherwise removed as soon
as possible, and afterwards the liquid must be allowed to rest until the
remaining indigo has subsided to the bottom. Or the suspended indigo
which does not rise to the surface may be separated by filtering.
In most cases two or more quantities of wool or other goods may be
washed in the same water, and when that is done the larger addition of
soda crystals, and the subsequent supply of acid are deferred until all
the quantities of wool that it is considered desirable to treat with the
same water have been washed, but prior to cach quantity of wool
after the first being put into the water an addition of about 2 ounces
soda crystals is dissolved in it for every 100 pounds of the quantity of
wool.
Any suitable or sufficiently economical carbonate may be substituted
for the soda crystals, and any suitable or sufliciently economical acid may
be used instead of hydrochloric or sulphuric acid.
In some cases the larger addition of soda crystals may be omitted
and the quantity of acid be correspondingly reduced, but there will then

page_text: be less effervescence and less of the indigo will be thrown to the surface,
a larger portion of it appearing in the subsequent deposit. The indigo
deposited at the bottom is not so pure as that thrown to the surface,
and it is therefore always better to separate as much as possible of the
indigo by throwing it to the surface.
The dissolving of small quantities of soda crystals in the water before
washing the goods is of importance, as the soda not only brightens the
color, but in the case of wool soften and improves it, and also causes
the separation of particles of indigo which would not be removed by
washing in pure water, but which are not really combined with the
fibres, being only temporarily adherent.
Having thus particularly described the said Invention and the manner
of performing the same, I have to state that I do not restrict myself to
the precise details herein-before referred to, but that what I believe to be
novel and original and claim as the Invention communicated to me by
the said Camille Bouhon, and secured to me by the hercin-before in part
recited Letters Patent is, the recovering of surplus indigo from textile
materials and fabrics by washing in water containing an alkaline car-
bonate, and subsequently treating the water with acid, substantially as
hercin-before described.
In witness whereof, I, the said John Auchinvolc, have hereunto
set my hand and scal, this Twenty-ninth day of January, in the