IMPROVEMENTS IN THE PREPARATION OF INDIGO FOR DYEING AND PRINTING, AND IN OBTAINING 'PURE' OR 'REFINED' INDIGO
Year: 1860

page_text: LETTERS PATENT to August Leonhardt, late of Berlin, but now of
Manchester, in the County of Lancaster, Chemist, for the Invention of
"IMPROVEMENTS IN THE PREPARATION OF INDIGO FOR DYEING AND PRINTING,
AND IN OBTAINING 'PURE' OR 'REFINED' INDIGO."
Sealed the 28th May 1861, and dated the 1st December 1860.
PROVISIONAL SPECIFICATION left by the said August Leonhardt at
at the Office of the Commissioners of Patents, with his Petition, on the
1st December 1860.
I, AUGUST LEONHARDT, late of Berlin, but now of Manchester, in the County.
of Lancaster, Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE PREPARATION OF INDIGO FOR DYEING AND PRINTING, AND 'IN
OBTAINING PURE' OR 'REFINED' INDIGO," to be as follows:―
My Invention consists in deoxydizing indigo for printing and dyeing, and.
also for obtaining "pure" or "refined" indigo by treating it with metals in a
finely divided state in the presence of an alkali or carbonate of an alkali, or
an alkaline earth. Of the metals, I have at present found iron and tin to
answer the purpose best; of the alkalies, soda or its carbonates; and of the earths
lime, but I do not confine myself thereto. The finely divided metals may be
obtained by precipitation, by reduction from their oxides, by "distillation, or
otherwise.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said August Leonhardt in the Great Seal Patent Office on the
1st June 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, AUGUST
LEONHARDT, late of Berlin, but now of Manchester, in the County of Lancaster,
Chemist, send greeting.
WHEREAS IIer most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of December, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said August Leonhardt, Her special license that I, the said August
Leonhardt, my executors, administrators, and assigns, or such others as I
the said August Leonhardt, 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 THE PREPARATION OF INDIGO FOR DYEING AND
PRINTING, AND IN OBTAINING PURE' OR 'REFINED' INDIGO," upon the condition,
amongst others, that I, the said August Leonhardt, by an instrument in
writing under my hand and seal, 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 Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said August Leonhardt, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement (that is to say):-
My Invention consists in deoxydizing indigo for printing and dyeing, and
also for obtaining "pure" or "refined" indigo, by treating it with metals in
a finely divided state in the presence of an alkali or carbonate of an alkali
or an alkaline earth. The method by which my Invention may be carried
into practical operation may be varied to a considerable extent; I will how-
ever point out certain processes which I have found to answer the object in
view. The great feature of my Invention is the finely divided condition of
the metals employed as distinguished from mere granulation; I therefore pro-
duce them by precipitation, reduction from their oxides, distillation, galvanic

page_text: action, or other similar process; or the end may be accomplished mechanically
by trituration or grinding, provided a material be obtained resembling sub-
stantially that resulting from the first-mentioned processes. In order to pre-
pare indigo for dyeing or printing, I take thirty pounds of finely divided indigo
of first quality, and mix it intimately with ten gallons of water; I then take
nine pounds of tin, prepared as above, and stir it well with twenty pounds of
caustic soda. The indigo is first boiled and the other ingredients added by
degrees, after which the whole is boiled until it assumes the yellow color which
indicates that the indigo is completely reduced. Or instead of the tin as
above, I can use nine pounds of zinc, seven pounds of iron, thirty pounds of
lead, seven pounds of arsenic, or ten pounds of antimony in combination with
the alkali as above. If lime be used in place of soda, I prefer tin as the metal
employed, and in the following proportions:-Finely ground indigo, thirty
pounds in ten gallons of water; tin, nine pounds, and caustic lime, fifteen
pounds, the whole being used as above described. The lime should be slacked
before it is added so as to obtain it in a pasty state. Indigo prepared as above
described may be diluted with water in the vat after the ordinary manner.
If for printing it may be thickened as is well understood, but in this case I
prefer the use of soda to other alkalies in the preparation. For producing
"pure" or "refined" indigo, I proceed according to any of the methods above
described, and then precipitate the indigo by acids or other well known means.
Having thus described, and ascertained the nature of my said Invention,
and the manner in which the same is to be performed, I desire it to be
understood that I claim as secured to me, the preparation of indigo for dyeing
and printing by treating it with finely divided metals in the presence of an
alkali or carbonate of an alkali, or an alkaline earth; also the production of
"pure" or "refined" indigo from a solution of indigo treated as above.
In witness whereof, I, the said August Leonhardt, have hereunto set my
hand and seal, this Thirty-first day of May, in the year of our Lord
One thousand eight hundred and sixty-one.
AUGUST LEONHARDT
AUGUST LEONHARDT (...)