A Coloring Matter Obtained from Logwood, and the Process of Producing same.
Year: 1893

page_text: Date of Application, 2nd Feb., 1898-Accepted, 6th May, 1898
A Coloring Matter Obtained from Logwood, and the Process of
Producing same.
I ALBERT EDGAR ALEXANDER, of 19 Southampton Buildings, Chancery
Lane, in the County of Middlesex, Fellow of the Chartered Institute of Patent
Agents, do hereby declare the nature of this invention, (communicated to me
from abroad by Henry Parkhust Wells of 93-99 Nassau Street, City, County
and State of New York, Lawyer) and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:
Heretofore the coloring matter extracted from logwood has been made and
used in the arts either in the form of a paste, a liquid, or of the consistency of a
thick pitob. All of these forms are open to many practical objections.
When in a liquid form, the coloring matter undergoes a change at low atmo-
spheric temperatures, losing much of its tinctorial power if chilled or frozen; it is
practically insoluble in cold water; it does not generally give a bloomy color when
dissolved in pure water; it is sticky and disagreeable to handle; more or less
always remains in the barrels to waste; it is troublesome to weigh out with the
required accuracy; it is liable to leakage from the barrels, and evaporation from
the open barrel in the dye room, thereby altering the standard of tinctorial power
and causing embarrassment; it often contains resinous and extractive matters
liable to injure the purity of the dye and prevent it from giving the color of cured
chip wood, and which also deposit and accumulate on the nips and rolls through
which the cloth to be dyed is passed and hence frequently causes injury to the
goods, as well as annoyance and loss to the manufacturer. Again, it contains more
or less latent coloring matter which is lost in certain processes of dyeing; further-
more its large content of water greatly increases the cost of transportation, storago
and handling.
When of the consistency of pitch, in which form it is known to the trade as
solid extract of logwood, besides having most of the objections to the liquid
extract, it is practically insoluble in cold water, and dissolves slowly even in
boiling water. It has frequently less bloom than the liquid extracts, or decoctions;
and if dried sufficiently to be capable of being powdered at a low atmospheric
temperature, it will melt, or run together, at higher atmospheric temperatures,
unless burned or incinerated, in which case the tinctorial power is greatly impaired,
if not destroyed.
My invention meets and overcomes all these objections, giving a stronger and
purer color. It consists of a process for making a solid coloring matter from
logwood which is not affected by the extremes of atmospheric temperature, and
which can be made, and will continue, and can be used in the form of a dry
powder similar to a coal tar dye, and which has the same advantages of stability
and rapid solubility in water, which are possessed by many coal tar dyes, and
which allow of the same facility and accuracy in determining the proper pro-
portions required. Being much freer from tannin and resinous matters it affords
a practical substitute for chip logwood, and avoids the labor, time and expense
required in the use of logwood in the form of chips.
To carry out my invention I heat ordinary liquid extract of logwood and mix
with it sodium or potassium nitrites in the proportion of about five pounds of solid
nitrite to each one hundred pounds of liquid extract of fifty-one degrees Twaddle.
The mixture is then stirred and evaporated to a point at which it becomes solid
and brittle on cooling.

page_text: The method I have employed with most satisfaction is the following:
I heat ordinary liquid extract of logwood of fifty-one degrees Twaddle to about
one hundred and forty degrees of Fahrenheit, and add to it in successive portions
an aqueous solution of potassium, or sodium nitrite, in the proportion given above,
thoroughly mixing them and maintaining the temperature. A copious evolution
of gas takes place which is facilitated by stirring, or agitation. The heating is
continued with frequent or continuous stirring until the evolution of gas has
ceased, and the mixture is sufficiently evaporated to form a solid mass on cooling,
which is sufficiently brittle to be ground into a powder, if so desired. A coloring
matter is thus obtained in the form of a powder which appears black in the
shadow and purplish-black in strong sunlight, and is practically soluble in cold
water and rapidly soluble in hot water, and having the characteristics heretofore
described.
It may be dyed on wool by the same method as logwood by mordanting the
material in the usual manner with potassium bichromate and potassium bitartarate,
but adding to the dye bath about twenty-five per cent. of the weight of the
coloring matter of acetic acid. The color thus produced is much stronger and
deeper than that produced by dyoing with equal quantities of logwood extract of
fifty-one degrees Twaddle.
The above method of procedure is the best to me at present known. But as heat
and time are frequently convertible conditions in chemical reactions I do not
limit myself to the temperaturo nor to the exact proportions above set forth; the
essence of my discovery and invention being, that when logwood extracts are
treated with nitrite of soda or potash or other suitable nitrite under such
conditions as to bring about a reaction between them, that a new product may be
produced having the characteristics hereinbefore set forth.
Having thus described my invention, what I claim as new and desire to
patent is:
First. In the art of making logwood extract, the improvement which consists
in adding to logwood extract an alkaline nitrite in the presence of water, and
causing a reaction between the nitrite and the extract substantially as described.
Second. In the art of making logwood extract, the improvement which consists
in adding to logwood extract an alkaline nitrite in the presence of water, causing &
reaction between the nitrite and the extract and evaporating the product to dryness,
substantially as described.
Third. As a new article of manufacture a coloring matter derived from logwood
extract by the incorporation therewith of an alkaline nitrite, and characterized
by the fact of its being a friable solid, soluble in cold water and rapidly soluble
in hot water, substantially as described.
Dated the 2nd day of February 1893.