IMPROVEMENTS IN EXTRACTING THE COLOURING MATTER FROM GUN LAC AND OTHER SIMILAR SUBSTANCES, AND IN TREATING THE RESIDUES THEREOF
Year: 1857

page_text: PROVISIONAL SPECIFICATION left by Clement Auguste Kurtz and Louis
Alcide Nori at the Office of the Commissioners of Patents, with their
Petition, on the 9th June 1857.
We, CLEMENT AUGUSTE KURTZ and LOUIS ALCIDE NORI, of Paris, in the
French Empire, Chemists, do hereby declare the nature of the said In-
vention for "IMPROVEMENTS IN EXTRACTING THE COLOURING MATTER FROM GUN
LAC AND OTHER SIMILAR SUBSTANCES, AND IN TREATING THE RESIDUES THEREOF,"
to be as follows:-
The gum lac or stick lac is broken up and the pieces of wood which it con-
tains are removed; it is then reduced to a fine powder by grinding it in a
mil or a mortar, and sifting it. One pound of this pulverized lac is carefully
and gradually sifted into five pints of water nearly boiling hot, and containing
about seventy grains of carbonate of soda, and when it has all been added the
water is boiled until the lac is perfectly fused. The liquid is then allowed to
repose, and the water or solution separates from the solid matter, which is
removed and again treated in a similar manner one or more times. The
solutions or extracts thus obtained are mixed together, and the undissolved
residue is placed on a filter to drain. To precipitate the colouring matter
from these solutions or extracts we employ a solution of tin prepared in the
following manner :-300 parts of salt of tin, free from zinc, are moistened
with a very small quantity of water, and when dissolved 180 parts of nitric
acid are added by small portions at a time; 600 parts of hydrochloric acid are
then added, and lastly, 200 or 300 parts of water are added. This solution

page_text: of tin is gradually added to the aforesaid extracts or solution of colouring
matter until the colouring matter is precipitated; it is allowed to subside until
the supernatant liquor becomes clear. A little water may be added, and the
clear liquor drawn off, and the deposit or precipitate is drained on a filter, and
has then the consistence of syrup. This deposit is then mixed with about a
third or a half of its weight of kaolin or pipe clay, moistened with water, and
pressed through a sieve with the deposit. The paste thus produced is made
into cakes and dried. It is prepared for use by dissolving it in boiling water,
and then adding cold water and a slight excess of hydrochloric acid. The
wool or other material to be dyed is dipped or boiled in this bath or solution
until it has acquired the desired colour. Variations in the tints may be
produced by the addition of tartar:
The resin or undissolved gum lac remaining from the first part of the opera-
tion is dissolved in 12 or 13 pints of boiling water containing about 21 ounces
of carbonate of soda. When dissolved, the solution is allowed to cool, and it
is. filtered, and bleached by chloride of soda; vinegar, or other suitable acid is
then added in slight excess to neutralize the alkali, and the resin is thus
coagulated in clots, and is skimmed off and placed in water heated to about
150° Fahr., when the clots unite in a porous mass. This is again melted
in boiling water to remove any remaining acid, and it is cast into moulds of
any required form. When operating upon lac dye, or the colouring matter
already extracted from the lac, we proceed at once to treat it with acid. For
this purpose it is moistened and ground up, and water is gradually added until
it is brought into a smooth semi-fluid paste. To 500 parts of lac dye so
treated we add from 50 to 80 parts of sulphuric acid, and mix them well
together, and occasionally stir the mixture for two or three days; 7000 or 8000
parts of water are then mixed with it, and the whole allowed to repose. The
-water is drawn off, and the residue again treated in a similar manner, and then
drained on a filter; 8 parts of powdered tartar, and 15 parts of moistened
pipe clay are ground up with the residue, and the paste made into cakes and
dried as before. This extract or preparation is dissolved in boiling water as
before, and a portion of solution of tin is added, and the wool or other mate-
rials are dyed in the solution. The above-mentioned proportions of the
different materials admit of being varied.