AN IMPROVED COMPOSITION OF MATTER TO BE USED AS A PAINT OR DYE
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents on the 3rd April 1883. Communicated
to him from abroad by The Leeds Manufacturing Company, of Brooklyn in the
County of Kings and State of New York United States of America
ALEXANDER MELVILLE CLARK of the firm of A. M and W. Clark of
53 Chancery Lane in the County of Middlesex Fellow of the Institute of Patent
Agents "AN IMPROVED COMPOSITION OF MATTER TO BE USED AS A PAINT OR
DYE [communicated to him from abroad by The Leeds Manufacturing
Company, of Brooklyn in the County of Kings and State of New York United
States of America]
"
In preparing this improved composition of matter I take five parts of picric acid
and thoroughly mix it with three parts of flavine, and to this compound add
twelve parts of nitric acid of 36° Baumé. The resulting compound is then slowly
boiled until the composition is evaporated to dryness, whereby a yellow dye is
obtained which produces an unusually fast and permanent color called echurine.
The object of evaporating the flavine and picric acid rather than first forming the
compound (which is hereinafter designated "nitro flavine") and then using with
picric acid, is that a more perfect mixture is produced by the method of
evaporation, and the resulting dye stuff is more economically and conveniently
manufactured.
In relation to the influence of picric acid it may be stated that the evaporation
of picric acid together with flavine and nitric acid has no chemical influence on the
resulting dye, as the picric acid can be separated unchanged from the “echurine”
but the advantage of the procedure above described is two fold vie first an intimate
mixture of the "nitro flavine" with the picric acid is effected more perfectly than
can be done by any mechanical means; and secondly a mass is obtained which can
be easily removed from the vessel in which the operation is conducted.
In relation to the influence of the nitric-acid, it may be stated of the chemical
change which occurs when nitric acid is added to flavine and picric acid, that a
very great increase of temperature takes place under the evolution of dense fumes
of nitric acid. Flavine, when simply treated with nitric acid, undergoes an entire
chemical change, as is shown by the increase of temperature and the evolution of
nitrous fumes.

page_text: The body produced is a nitro derivative of flavine and is best distinguished by
the name of "nitro flavine" which produces an entirely different dye-stuff from
picric acid, which dyes silk of a greenish yellow color, whilst "nitro flavine" dyes
it a salmon color. When the nitro flavine is added to the picric acid in the manner
described above, the resulting dye-stuff dyes silk the color of "echurine."
The body resulting from the treatment of flavine with nitric acid and subsequent
evaporation is the nitro compound (nitro flavine) and differs in every respect from
the original body. Besides "nitro flavine," however, a small amount of the flavine
undergoes decomposition by the action of the nitric acid and a minute amount of
picric acid is produced at the same time. Neither oxalic acid nor genercitine are
produced, as appears from a further examination of the body resulting from the
action of the nitric acid on the flavine.
The dyeing properties of the compound produced by the action of the nitric acid
on the flavine are due to "nitro flavine" and not to genercitine as is shown by the
absence of genercitine. The action of the nitric acid also is to increase the
solubility of the compound, which appears from the fact that while flavine is very
slightly soluble in water "echurine" is almost entirely so. There is no free nitric
acid in the compound if the same is prepared properly and the mass is evaporated
to complete dryness.
The color of the dye stuff produced by the evaporation of nitric acid, picric acid
and flavine in the manner above described will vary between the salmon color due
to the nitro flavine and the peculiar tint of yellow due to picric acid, according to
the relative amounts of flavine, picric acid, and nitric acid originally employed,
and the thoroughness with which the chemical change due to evaporation to dryness
is brought about.
In case any flavine escapes conversion by nitric acid into "nitro flavine" by the
first operation it is more completely changed by a second evaporation and the
resulting dye has a corresponding difference of tint due to the larger per centage of
"nitro flavine." All these various shades of color varying from salmon to
greenish yellow are produced in the manner set forth, from various portions of nitric
acid, picric acid and flavine, and are all comprehended under the name of
"echurine."