IMPROVE. MENTS IN THE MANUFACTURE OF DRY SULPHURIC ACID, AND IN THE MANUFACTURE OF SMOKING OR NORDHAUSEN SULPHURIC ACID,
Year: 1847

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PAUL
GILBERT PRELIER, of Rue de Rivoli, Paris, in the Kingdom of France,
Gentleman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-ninth day of
June, One thousand eight hundred and forty-seven, in the eleventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Paul Gilbert Prelier, my exors, admors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Paul Gilbert
Prelier, my exors, admors, and assigns, or such others as I, the said Paul
Gilbert Prelier, my exors, adinors, or assigns, should at any time agree with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, and in the
Islands of Jersey, Guernsey, Alderney, Sark, and Man, and also in all Her
said Majesty's Colonies and Plantations abroad, the Invention of "IMPROVE.
MENTS IN THE MANUFACTURE OF DRY SULPHURIC ACID, AND IN THE MANUFACTURE
OF SMOKING OR NORDHAUSEN SULPHURIC ACID," communicated to me from abroad;
in which said Letters Patent is contained a proviso, that I, the said Paul
Gilbert Prelier, shall cause a particular description of the nature of the said
Invention, and in what manner the same is to be performed, by an instrument
Prine Rd 1

page_text: in writing under my hand and seal, to be inrolled in Her said Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Paul Gilbert Prelier, do hereby declare that the nature of the said Invention,
and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, that is to say :-
There being a great affinity between sulphuric acid and water it is very
difficult to concentrate sulphuric acid, even at sixty-six degrees of Baumés
areometer. By reason of this, in order to obtain this dry acid it is requisite
to take simple sulphates, and to combine them with a fresh proportion of acid,
for the purpose of making double sulphates, which are to be decomposed by
the action of heat. By this means dry sulphuric acid is obtained. The
making of this acid naturally leads to the making of Nordhausen acid, since
the latter is composed but of sulphuric concentrated at sixty-six degrees, in
which there has been a dissolution of the dry acid. The more there is of the
dry acid the more the density of the acid encreases; therefore, in proportion
to the quantity thereof that is added thereto a smoking acid will be obtained,
weighing by the areometer sixty-seven, sixty-eight, sixty-nine degrees, but at
this last degree it will always be crystallized, in which state it cannot be
employed in the arts. This principle being understood, I describe the whole
of the operation in a few words, convinced that any one accustomed to the
manufacture of acid will be enabled to manufacture this acid without any
farther description.
The apparatus employed consists of retorts of freestone heated in galleries.
I have not annexed anyplans,for all manufacturers of chemical products know
how to make use of one and the other. The furnaces may be constructed
in various ways, as every one follows his own ideas on this subject.
When commencing I take one hundred parts of sulphate of soda, two
parts of sulphate of potash, and two parts of sulphate of lime. The above are
the proportions I prefer touse, but by varying the quantities and by employing
even sulphate of soda alone, dry acid is always obtained. I have adopted
this formula because it seems to me to be the best, and I have always found it
yield more dry acid. These mixtures being placed in retorts, I place them in
a suitable furnace in the galleries of the furnace, and then by means of a
bent glass tube 1 introduce the acid into the retorts. I close up these stoves
and heat them slightly at first; shortly after drops of water which proceed
from the acid are seen to drop, then the water acidulates; afterwards acid at

page_text: forty degrees, and fifty, and then at sixty-six degrees is obtained, and finally
one sees that the acid which is running smokes. To judge correctly water is
placed below in a vessel, and every drop that falls into it makes the same
noise as if a red-hot iron were thrust in it. This is the decisive moment, the
end is obtained, for this acid which make a noise in the water is dry acid.
Vessels or receivers are placed below the retorts, they are luted with clay, the
heating is strongly continued until nothing more drops. Dry acid which is
not used alone in the arts has been obtained by such way. If it be wished
to obtain Nordhausen sulphuric acid, when the recipients are placed to receive
the dry acid it is only necessary to add concentrated acid at sixty-six degrees,
the dry acid dissolves and encreases the density to sixty-seven, sixty-eight, and
sixty-nine degrees, according as a more or less quantity has been introduced.
However, when the acid is to be placed in bottles to be delivered to the trade,
if it be too strong, acid at sixty-six degrees is to be added, until reduced to the
proper degree. By these means perfectly clear acid is always obtained limpid,
and never colored like that of Nordhausen; besides which, it is never charged
with earth or other foreign bodies.
In witness whereof, I, the said Paul Gilbert Prelier, have hereunto set
my hand and seal, this Fourteenth day of December, in the year of
our Lord Oue thousand eight hundred and forty-seven.
PAUL GILBERT (L.S.) PRELIER.
Taken and acknowledged by Paul Gilbert
Prelier (party hereto), at Paris, in the
Kingdom of France, this 14th day of
This is the Specification referred to in the Affidavit of William Heury
Ritchie, sworn before me this 29 day of December, 1847,
J. JEFFERSON.
William Henry Ritchie, of Lincoln's Inn, in the County of Middlesex,
Gentleman, maketh oath and saith, that he is acquainted with the manner and
character of the handwriting of Thomas Pickford, Her Britannic Majesty's
Consul at Paris, in the Kingdom of France. And this Deponent further
saith that the signature of "Thomas Pickford," set, subscribed, or written in
the margin of the Specification hereunto annexed, marked A, and dated the

page_text: Fourteenth day of December instant, and purporting to be executed by Paul
Gilbert Prelier, of Rue de Rivoli, Paris, aforesaid, whereby it is stated that
the said Specification was acknowl-dged by him, the said Paul Gilbert Prelier,
before the said Thomas Pickford, on the said Fourteenth day of December, at
Paris aforesaid, is of the proper handwriting of the said Thomas Pickford.
AND BE IT REMEMBERED, that on the Oath of William Henry Ritchie,
the Specification aforesaid was enrolled word for word as above written. And
also the Specification aforesaid was stamped according to the tenor of the
Statute made for that purpose.