IMPROVEMENTS IN THE PRE- PARATION OF BODIES IN WHICH NITROGEN IS SUBSTITUTED FOR HYDROGEN
Year: 1866

page_text: LETTERS PATENT to Peter Griess, of Burton-on-Trent, in the County of
Stafford, Chemist, and Heinrich Caro, of Manchester, in the County of
Lancaster, Chemist, for the Invention of "IMPROVEMENTS IN THE PRE-
PARATION OF BODIES IN WHICH NITROGEN IS SUBSTITUTED FOR HYDROGEN."
Sealed the 25th January 1867, and dated the 28th July 1866.
PROVISIONAL SPECIFICATION left by the said Peter Griess and Heinrich
Caro at the Office of the Commissioners of Patents, with their Petition, on
the 28th July 1866.
We, PETER GRIESS, of Burton-on-Trent, in the County of Stafford,
Chemist, and HEINRICH CARO, of Manchester, in the County of Lancaster,
Chemist, do hereby declare the nature of the said Invention for 'IMPROVE-
MENTS IN THE PREPARATION OF BODIES IN WHICH NITROGEN IS SUBSTITUTED FOR
HYDROGEN," to be as follows:-
Our Invention consists in the employment of a method which enables us
to prepare commercially a certain series of bodies in which nitrogen is sub-
stituted for hydrogen, and which was discovered by one of us, the said Peter
Griess, and well known, to chemists as being obtained by the action of nitrous
acid upon amido compounds remarkable, as is familiar to chemists, for the
variety of compounds which they produce. Those obtained by the substitu-
[Price 8d.]

page_text: tion of one atom of nitrogen for three atoms of hydrogen in one atom of
amido compound are highly explosive in the dry state, and can be applied
as explosive substances; and products of the decomposition of these bodies
have been found useful as colouring matters or dye stuffs. The practical
application of this class of substances has only been impeded by the difficulty
of separating them from their solutions. This, which constitutes our present
improvement, we effect by treating amido compounds with nitrous acid, as well
understood by chemists for the preparation of this class of azo compounds,
and adding to the solution thus obtained either chromic acid or mixtures
of hydrochloric and chromic acids. This causes a separation of a crystallized
precipitate which is a compound of the above acids with the nitrogenized
bodies..
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Peter Griess and Heinrich Caro in the Great Seal Patent
Office on the 28th January 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, PETER
GRIESS, of Burton-on-Trent, in the County of Stafford; Chemist, and HEINRICH
CARO, of Manchester, in the County of Lancaster, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of July, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto us, the
said Peter Greiss and Heinrich Caro, our executors, administrators, and
assigns, or such others as we, the said Peter Greiss and Heinrich Caro,
our 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 PREPA-
RATION OF BODIES IN WHICH NITROGEN IS SUBSTITUTED FOR HYDROGEN," upon the
condition (amongst others) that we, the said Peter Griess and Heinrich Caro,
by an instrument in writing under our hand and seals (or under the hand and
seal of one of us), 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.

page_text: NOW KNOW YE that I, the said Peter Griess, do hereby declare the
nature of our 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):--
Our Invention consists in a method which enables us to prepare com-
mercially a new series of bodies belonging to that class of compounds in which
nitrogen is substituted for hydrogen, and which series was discovered by me
the said Peter Greiss. Many already known substances of this class (obtained
as is familiar to chemists by the action of nitrous acid or amido compounds,)
are distinguished by their striking physical properties and also by their great
number of derivatives. Those obtained by the substitution of one atom of
nitrogen for three atoms of hydrogen in one atom of amido compound are
highly explosive and may be applied as fulminating substances, while their
products of decomposition have been found useful as coloring matters and dye
stuffs. The practical application of these compounds has only been impeded by
the difficulty of separating them from their solutions. This difficulty has been
overcome by us and constitutes our present improvement. This improvement
we effect by treating the solutions of the azo compounds obtained in the manner
already described by one of us, the said Peter Greiss, and as is now well known
to chemists with a mixture either of hydrochloric acid and chromic acid or
chromic acid only, which treatment causes the separation of a crystallized
precipitate consisting of a compound of hydrochloric acid and chromic acid.
with the nitrogenized bodies, or of compounds of the latter with chromic acid
only. For example, we proceed as follows:-We take two parts of hydro-
chlorate of analine, eight parts of water, four parts of hydrochloric acid;
through this mixture, which must not be allowed to rise in temperature
higher than 70° F. we pass a current of nitrous acid as long as this gas
continues to be absorbed, the process thus far being that already-made known
by me Peter Greiss; we then add a cold saturated solution of two parts of
bichromate of potash, previously mixed with one and a half parts of hydro-
chloric acid, sp. grv. 1'15, when immediate crystallization ensues. The
crystals are a compound of diazobenzul with hydrochloric acid and chromic
acid, and may be separated from the mother liquor by filtering and pressing.
On account of their explosiveness they must be carefully dried at a low
temperature. Instead of operating with a current of nitrous acid gas, solutions
of nitrites, such as nitrite of sodium or calcium may be employed. These
solutions are slowly added to the mixture of amido compounds with acids,
until an excess of nitrous acid is perceived by its smell. The precipitation of
the nitrogenized bodies by means of hydrochloric acid and chromic acid is

page_text: effected as above. The following are convenient proportions for this modifi-
cation of the process:-1 part of hyhrochlorate of analine, 4 parts of water,
three parts of hydrochloric acid, sp. grv. 1'15; two parts of solution of
commercial nitrate of lime, of 13 sp. grv., one part of bichromate of
potash dissolved in water. Similar chromates of azo compounds are produced
by submitting to an analogous treatment other amido compounds, such as
toluidine, naphtaline, rosaniline, ámido-benzoil acid, benzidine, &c. To obtain
the compounds of nitrogenized bodies with chromic acid only we proceed as
follows: Amido compounds are wholly or partially dissolved in sulphuric
acid or nitric acid, and then treated in the above manner with nitrous acid.
To the solution thus obtained a cold saturated solution of bichromate of potash
is then added when immediate formation of crystals of the azo compounds with
chromic acid takes place; these are separated from the mother liquor and
dried as mentioned above. For example, we use the following proportions:-
Two parts of toluidine, four parts of sulphuric acid diluted with thirteen parts
of water; three parts of solution of commercial nitrate of sodium, sp. grv.
13; two parts of bichromate of potash dissolved in water.
Having thus described and ascertained the nature of our said Invention, and
the manner in which the same is to be performed, we desire it to be under-
stood that we claim as secured to us under the above in part recited Letters
Patent, the separating the aforesaid azo compounds from their solution in the
solid and crystallized state by means of chromic acid or mixtures of chromic
acid and hydrochloric acid or the salts thereof.
In witness whereof, I, the said Peter Greiss, have hereunto set my hand
and seal, this Twenty-fifth day of January, in the year of our Lord One
thousand eight hundred and sixty-seven.
P. GRIESS. (L.S.)