IMPROVEMENTS IN THE MANUFACTURE OF PLUMBAGO CRUCIBLES AND OTHER VESSELS IN PLUMBAGO SUITABLE FOR CHEMICAL AND METALLURGICAL PURPOSES
Year: 1880

page_text: LETTERS PATENT to Samuel Arthur Peto, of South Kensington,.in the County
of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF PLUMBAGO CRUCIBLES AND OTHER VESSELS IN PLUMBAGO,
PROVISIONAL SPECIFICATION left by the said Samuel Arthur Peto at the
Office of the Commissioners of Patents on the 23rd April 1880.
SAMUEL ARTHUR PETO, of South Kensington, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE MANUFACTURE OF PLUMBAGO CRUCIBLES
AND OTHER VESSELS IN PLUMBAGO, SUITABLE FOR CHEMICAL AND METALLURGICAL
PURPOSES."
This Invention relates to improvements on an Invention for which Letters
Patent were granted to me dated the Ninth day of October 1878, No. 3992, tho
object of the present improvements being to simplify the method or process by
which the crucible or other vessel in plumbago is rendered damp proof.
In carrying out my present improvements the crucible may, before baking, bo
coated or covered with a suitable compound, such as is described in the Specifi-
cation of my said former Letters Patent, but such preliminary coating may in some
cases be omitted; in either case I proceed as follows:-
Directly the crucible is drawn from the kiln, that is to say, while it is still warm
(the temperature being so low as to obviate the risk of combustion of the coating
hereinafter mentioned) I either dip it in or coat it with a compound consisting of
about six parts of rosin or anologous gum and a sufficient quantity of turpentine
or analogous spirit as will assist in dissolving the rosin, a small quantity of tallow
or oil being in some cases added. Varnishes of an analogous character when
properly prepared may also be employed, but will be found expensive.
It will be understood that this compound is employed while in a liquid or heated
state.
If, from the small size of the crucible, it should be found that the retained heat
is not sufficient to thoroughly dry the hereinbefore described coating it will be
necessary to again warm the crucible to complete the process.
When the coating is not applied directly the crucible is drawn from the kiln, or,
in other words, if the crucible shall have been allowed to absorb moisture before
applying the coating, it will be necessary to thoroughly re-heat the crucible to a
temperature above 212° Fahrenheit previous to treating it by the process herein-
before described, so as to drive off all the absorbed moisture.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Samuel Arthur Peto in the Great Seal Patent Office on the 22nd
October 1880).
SAMUEL ARTHUR PETO, of South Kensington, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE MANUFACTURE OF PLUMBAGO CRUCIBLES
AND OTHER VESSELS IN PLUMBAGO, SUITABLE FOR CHEMICAL AND METALLURGICAL
PURPOSES."
This Invention relates to improvements on an Invention for which Letters
Patent were granted to me dated the Ninth day of October, One thousand eight
hundred and seventy eight, Number 3992, the object of the present improvements
being to simplify the method or process by which the crucible or other vessel in
plumbago is rendered damp proof.
In carrying out my present improvements the crucible may, before baking, be
coated or covered with a suitable compound, such as is described in the Specifi-
cation of my said former Letters Patent, but such preliminary coating may generally
be omitted; in either case I proceed as follows:-
Directly the crucible is drawn from the kiln, that is to say, while it is still warm
(the temperature being so low as to obviate the risk of combustion of the coating
hereinafter mentioned) I either dip it in or coat it with a compound consisting of
about six parts of rosin or analogous gum and a sufficient quantity of turpentine
or analogous spirit as will assist in dissolving tho rosiu, a small quantity of tallow
or oil being in some cases added. Varnishes of an analogous character when
properly prepared may also be employed, such as the following, consisting of about
one part of pitch, three parts of rosin, and four parts of turpentine. It will be
understood that the compound is employed while in a liquid or hented state.
In practice I have found that it is expedient to apply a second coating of the
herein before described varnish, or of one in which five parts of methylated spirit
are substituted for the turpentine.
If, from the small size of the crucible, it should be found that the retained heat
is not sufficient to thoroughly dry the hereinbeforo described coating it will be
necessary to again warm the crucible to complete the process.
When the coating is not applied directly the crucible is drawn from the kiln, or,
in other words, if the crucible shall have been allowed to absorb moisture before
applying the coating, it will be necessary to thoroughly re-heat the crucible to a
temperature above two hundred and twelve degrees Fahrenheit previous to treating
it by the process herein before described, so as to drive off all the absorbed
moisture.
Having thus described ny said Invention, and the best means with which I
am acquainted for carrying the same into effect, I wish it to be understood
that I do not confine myself to the precise details herein laid down, as the same
may be varied without departing from the principle of my Invention, but what
I do claim is,--
The methods hereinbefore described of rendering plumbago crucibles and other
vessels of plumbago damp-proof and non-porous.
In witness whereof, I, the said Samuel Arthur Peto, have hereto set my
hand and seal, this Fourteenth day of October, in the year of our Lord
One thousand eight hundred and eighty.