AN IMPROVED MODE OF RENOVATING FILES BY, AN ELECTRC-CHEMICAL PROCESS
Year: 1868

page_text: LETTERS PATENT. to Arthur Charles Henderson, of No. 31, Charing
Cross, in the County of Middlesex, Patent Agent, for the Invention
of. "AN IMPROVED MODE OF RENOVATING FILES BY, AN ELECTRC-CHEMICAL
PROCESS." A communication from abroad by le Comte Henry do
la Tour du Breuil, le Comte Thomas de Dienheim Brochocky, and
Horace Baynes, Engineer, all residing at Florence, in the Kingdom
of Italy
PROVISIONAL SPECIFICATION left by the said Arthur Charles
Henderson at the Office of the Commissioners of Patents, with
his Petition, on the 7th May 1868.
I, ARTHUR CHARLES HENDERSON, of No. 31, Charing Cross, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "AN IMPROVED MODE OF RENOVATING FILES BY AN
ELECTRO-CHEMICAL PROCESS," a communication to me from abroad by le
Comte Henry de la Tour du Breuil, le Comte Thomas de Dienheim
Brochocky, and Horace Baynes, Engineer, all resident at. Florence, in
the Kingdom of Italy, to be as follows:-

page_text: Invention consists in submitting old or worn files to the simultaneous
action of an electric current and of a mixture of acids diluted with
water, the former encouraging the oxydation of the metal, and the
latter producing a saline combination with the oxyds formed; acids,
such as chloridic acid, susceptible of determining the formation of a
salt without oxydation can be also employed.
The manner of procedure is as follows:-The files being previously
freed from grease by placing them in a warm bath composed of potash,
soda, or other suitable matter for dissolving fatty substances, are then
well brushed so as to remove any adherent particles or foreign matters
that may remain between the teeth, they are then completely immersed
in an acid solution composed of azotic acid and sulphuric acid in the
proportions of two parts by weight of azotic acid to one part of
sulphuric acid, to which are added eighteen parts of water. The files
are suspended independently in this liquid by means of a metal support
common to all, which is put in communication with one of the poles
of an electric current, the other pole being plunged directly into the
solution, the usual care being taken that the current is not dispersed.
The duration of this operation cannot be previously estimated, but
must be regulated according to the degree of purity, of concentration
and dilution of the acids, and the intensity of the current, the condition
of wear that the files are in, the size of their teeth, and the quality and
temper of the steel, but on an average not less than half an hour
is required. The current is established by placing the positive pole or
charcoal in communication with the files, and the negative pole or
zinc with the solution and is maintained thus during the whole
operation.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Arthur Charles Henderson in the Great Seal
Patent Office on the 6th November 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
CHARLES HENDERSON, of No. 31, Charing Cross, in the County of
Middlesex, Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen
Victoria, by Her
Letters Patent, hearing date the Seventh day of May, in the year of

page_text: our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reigu, did, for Herself, Her heirs and successors, give
and grant unto ine, the said Arthur Charles Henderson, Her special
licence that I, the said Arthur Charles Henderson, my executors,
administrators, and assigns, or such others as I, the said Arthur Charles
Henderson, my 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 "AN IMPROVED MODE OF RENOVATING FILES BY AN ELECTRO-
CHEMICAL PROCESS," a communication to me from abroad by le Comte
Henry de la Tour du Breuil, le Comte Thomas de Dienheim Brochocky,
and Horace Baynes, Engineer, all resident at Florence, in the
Kingdom of Italy, upon the condition (amongst others) that I, the
said Arthur Charles Henderson, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands and
seals, 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.
NOW KNOW YE, that I, the said Arthur Charles Henderson, do
hereby declare the nature of my 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:-
The electro-chemical process forming the subject of the present
Invention consists in submitting old or worn files to the simultaneous
action of an electric current and of a mixture of acids diluted with
water, the former encouraging the oxydation of the metal, and the
latter producing a saline combination with the oxydes formed. Acids,
such as chloridic, which are susceptible of determining the formation
of a salt without oxydation may also be employed.
The manner of procedure is as follows:-The files being previously
freed from grease by placing them in a warm bath composed of potash,
soda, or other suitable matter for dissolving fatty substances, are then
well brushed so as to remove any adherent particles or foreign mattera
that may remain between the feeth; they are then completely immersed

page_text: water.
in an acid solution composed, for instance, of azotic acid and sulphuric
acid in the proportions of two parts by weight of azotic acid Az 0³,
to one part of sulphuric acid S 0³, to which are added 18 parts of
The files are suspended independently in this liquid by means
of a metal support common to all, which is put in communication with
one of the poles of an electric current, the other pole being plunged
directly into the solution, the usual care being taken that the current
is not dispersed. The duration of this operation cannot previously be
estimated, but must be regulated according to the degree of purity, of
concentration and dilution of the acids, and intensity of the current,
the condition of wear of the files, the size of their teeth, and the quality
and temper of the steel, but on an average not less than half an hour is
required. The current is established by placing the positive pole or
charcoal in communication with the files, and the negative pole or zinc
with the solution, and is maintained thus during the whole operation,
care being taken that the current is not dispersed. On examining the
files the time for withdrawing them will be ascertained; they are then
carefully washed and brushed, and afterwards protected from oxydation
by the usual means employed for new files. The intensity of the current
and the strength of the solution of the acids is determined by the size
and number of files to be treated at a time, and the proportions of
the ingredients may vary according to circumstances, for instance, in
taking of water 1000 parts, sulphuric acid S 0³, 35 to 40 parts,
azotic acid Az 0, 70 to 80 parts, the operation works slower it is truc
but more equally, and consequently it is easier to watch its progress,
An
as to avoid letting pass the time for removing the files from the
bath, as should they remain too long they would be injured.
advantage is also gained in dividing the operation into two or more periods
according to the nature and degree of wear of the files, taking care to
wash and gently brush them between each interval so as to remove any
deposit formed thereon. The teeth of the files being the most
prominent feature, the electric current acts more vigourously on them
than the other parts by concentrating the action of the acids thereon;
this theory may be proved by plunging a cylindrical metal bar into
the bath alluded to and submitting it to the electric current, on
removing it it will be seen that it is not acted on uniformly; but has
become conical and terminates by taking the form of a sharp point
This process replaces the old method of re-sharpening with several
advantages, amongst which that of doing away with the necessity of

page_text: previously softening the files, and admits of giving them a
less powerful mordant according to the length of the operation, which
may also be applied to needles of all kinds after being tempered, with
a saving in time, labour, and expense.
Having thus described my Invention, what I claim and desire to
secure by Letters Patent is, the employment of the acid bath in
conjunction with an electric current for renovating files in the manner
herein-before mentioned.
In witness whereof, I, the said Arthur Charles Henderson, have
hereunto set my hand and seal, this Sixth day of November, in
the year of our Lord One thousand eight hundred and sixty-
eight.
A. C. HENDERSON. (L.S.)