IMPROVEMENTS IN TREATING A CERTAIN KIND OF INDIGO
Year: 1854

page_text: LETTERS PATENT to Antoine Louis Péter, of Lyons, in the Empire of
France, and of 16, Castle Street, Holborn (City), London, for the
Invention of "IMPROVEMENTS IN TREATING A CERTAIN KIND OF INDIGO."
Invention of
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'IMPROVEMENTS IN TREATING A CERTAIN KIND OF INDIGO."
PROVISIONAL SPECIFICATION left by the said Antoine Louis Péter at
the Office of the Commissioners of Patents, with his Petition, on the 13th
June 1854.
I, ANTOINE LOUIS PETER, of Lyons, in the Empire of France, and of 16,
Castle Street, Holborn (City), London, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN TREATING A CERTAIN KIND OF INDIGO" to
be as follows:-
My improvements consist in refining a certain kind of indigo known by the
name of Manilla indigo, by expelling from it considerable portions of saline
and calcareous matters, which at present render it unfit for most purposes.
My method consists in carefully washing the said indigo, and in treating it with
an acid capable of forming soluble salts with lime, alum, iron, magnesia, &c., &c.
The quantity of acid thus used varies according to the quality of the indigo,
and it has to be poured on it gradually until no more effervescence is produced.
The kind of acid I prefer is the hydrochloric, both on account of its cheapness
and good effects; but any other suitable acid may be used equally well. The
salts thus formed are now to be removed by repeated washing and filtering.

page_text: The matter gathered on the filter has to be squeezed and dried, after which it
is ready for use. The reduction of weight which the above said kind of indigo
thus undergoes varies from thirty to seventy-five per cent.; but it does not
affect the blue colouring matter of the indigo, and leaves its price still
sufficiently low to offer considerable saving over the other kinds of indigo,
upon which the above treatment produces no appreciable result.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Antoine Louis Péter in the Great Seal Patent Office on the
12th December 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANTOINE
LOUIS PETER, of Lyons, in the Empire of France, and of 16, Castle Street,
Holborn (City), London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of June, in the year of our Lord
One thousand eight hundred and fifty-four, in the seventeenth year of
Her reign, did; for Herself, Her heirs and successors, give and grant unto
me, the said Antoine Louis Péter, Her special licence that I, the said Antoine
Louis Péter, my executors, administrators, and assigns, or such others as I,
the said Antoine Louis Péter, 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 "IN-
PROVEMENTS IN TREATING A CERTAIN KIND OF INDIGO," upon the condition
(amongst others) that I, the said Antoine Louis Péter, 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 bo
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 Antoine Louis Péter, 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:-
My improvements consist in refining a certain kind of indigo known by the
name of Manilla indigo, by expelling from it considerable portions of saling

page_text: and calcareous matters, which at present render it unfit for most purposes.
The method I use to this effect consists in carefully crushing the said indigo,
and in treating it with an acid capable of forming soluble salts with lime, alum,
iron, magnesia, &, &. The salts thus produced have to be. eliminated by
suitable washing operations, and, finally, the paste or pulp gathered upon
filters has to be dessiccated. Amongst the acids that may be employed I prefer
using hydrochloric acid, on account of its particular properties and its low price.
The acid is diluted with twice or three times its weight of water; but this pro-
portion of water may be increased or diminished at will, taking care, however,
in the former case to wash a little more after the operation than if a more
diluto solution were used. The quantity of acid thus applied varies according
to the quality of the indigo; thus, one hundred parts of good indigo require
about fifty to sixty concentrated hydrochloric acid; one. hundred parts of
inferior indigo require as much as one hundred and twenty-five parts. The.
The modus operandi is as follows:--The acid is gradually poured on the indigo
which has been crushed and diluted in such manner as to form a liquid paste.
At each addition a rather strong effervescence is produced, and when the
addition of acid ceases to produce an effervescent motion in the mass no more
acid is added, and the whole is left to settle, and then is put upon filters, so as
to remove any saline matter, which leaves the colouring matter with a yellowish
colour. The lavatory process may be repeated once or several times with hot
water, which may be pure or alkaline, and at last the paste is pressed and dried;
these slight differences in the treatment depending on the use for which the
colouring matter is intended. Manilla indigo thus treated suffers a considerable
reduction of weight, which reduction may amount to seventy-five per cent. of
the raw material; but at the same time, as the colouring matter is considerably
concentrated by the process, its price still remains sufficiently low for allowing
it to be used economically in comparison with native pure indigo, upon which
the above treatment produces no appreciable result, as said indigo contains
merely traces of calcareous matter.
Hitherto the purification of indigo, the same as that of most colouring
matters used in commerce, has been treated as a process of the laboratory only.
All books on chemistry talk of treating the different kinds of indigo, without
regard to their quality or origin, by means of water, diluted acids, concentrated
alkalis, alcohol, rectified ether, and similar matters, so as to extract from said
indigo gluten, oxyds of iron. of calcium, of alumina, besides indigo brown and
red, also a peculiar resin, and other substances. As another means of purifying
poor indigo sublimation has been proposed; but all these means have been
devised merely for obtaining the blue colouring matter in a state of chemical

page_text: purity; for the purpose of testing the relative value of different qualities of
indigo, they were always confined to the analytical operations of laboratories,
and never received any practical application. Indigo has also sometimes been
treated with alkalis or de-oxydizing substances for dissolving the bluo colouring
matter, and then precipitating it by contact with air; but this process was
chiefly applied to superior qualities of indigo without regard to expense, for the
purpose of extracting from them the indigo brown, which spoils the beauty of
the colour. Thus, it is fully known, that whilst the best qualities of indigo are
used for valuable fabrics, and the lower kind for common printing and dyeing
purposes, Manilla indigo is altogether rejected, as unfit for most uses, and
especially for preparing soluble blues, whose base is sulphate of indigo, and
which are consumed in large quantities. The distinguishing feature of this
Invention hence consists in indicating the precise nature of the impurities
which render Manilla indigo useless, and to afford cheap and practical means
for rectifying the same, so as to render it applicable on an equal footing with
other qualities, and in particular cases even more advantageously than ordinary
indigo, on account of the peculiar redness which the Manilla indigo naturally
possesses.
Having thus described the nature of my Invention, and the manner in
which the same is or may be carried into effect, I wish it to be understood
that what I claim as novel and secured to me by the herein-before in part
recited Letters Patent is,-
Extracting from Manilla or Philippine Islands indigo any calcareous and
earthy matters by means of acids or acid solutions, which, combining with said
impurities, give rise to soluble salts, in the manner described above, or any
analogous one, for rendering said kind of indigo fit for manufacturing purposes.
In witness whereof, I, the said Antoine Louis Péter, have hereunto set
my hand and seal, this Sixth day of December, in the year of our
Lord 1854.