A NEW OR IMPROVED COMPOUND FOR FILLING DECAYED TEETH AND FOR GENERAL DENTAL PURPOSES
Year: 1878

page_text: LETTERS PATENT to Thomas Fletcher, of Warrington, in the County of
Lancaster, for the Invention of "A NEW OR IMPROVED COMPOUND FOR
FILLING DECAYED TEETH AND FOR GENERAL DENTAL PURPOSES."
Sealed the 20th June 1879, and dated the 27th December 1878.
PROVISIONAL SPECIFICATION left by the said Thomas Fletcher at the
"
Office of the Commissioners of Patents on the 27th December 1878.
THOMAS FLETCHER, of Warrington in the County of Lancaster. A NEW OR
IMPROVED COMPOUND FOR FILLING DECAYED TEETH AND FOR GENERAL DENTAL
PURPOSES."
I use an acid phosphate of tin in a cement which may be formed by mixing this
material with lime, alumina, or their basic silicates, heavy oxide of zinc, oxide of
tin, magnesia, or other powders which have the property of combining with it and
setting into a hard mass, as a filling material for decayed teeth, for building up
broken teeth, repairing artificial teeth, and general dental purposes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Fletcher in the Great Seal Patent Office on the 27th June
1879.
THOMAS FLETCHER, of Warrington, in the County of Lancaster.
"A NEW OR
IMPROVED COMPOUND FOR FILLING DECAYED TEETH AND FOR GENERAL DENTAL
PURPOSES."
I produce a material for filling decayed teeth, for building up broken teeth,
repairing artificial teeth, and for general dental purposes, as follows:-
I make a thick solution or paste of perphosphate of tin by dissolving it with the
assistance of heat when wet and freshly precipitated in phosphoric acid. The per-
phosphate of tin which I employ is a compound not commercially known, and is
produced by precipitating from a weak solution of perchloride of tin made slightly
acid by phosphate of soda. The ordinary phosphate precipitated from the proto-
chloride of tin, which is the common commercial salt, is useless for the purpose.
The proportion of free phosphoric acid required varies with the properties, time
required for the cement to harden, and the purposes to which the material is to be
applied, and must always be obtained by experiment with the powders which are
intended to be used. This solution or paste when mixed with lime, alumina, or
their basic silicates, heavy oxide of zinc, oxide of tin and lead, and many other
eartby powders, has the property of setting into a hard mass, suitable for the
purposes above specified. The powder I prefer is a mixture of 1 lime, 3 silica, and
6 alumina (all chemically pure), fused together at a very high temperature and
reduced to a fine powder.
Having thus particularly described and ascertained the nature of this my said
Invention, together with the best methods with which I am acquainted for carrying
the same into practical effect, I wish it to be understood that I do not confine myself
to the proportions or ingredients hereinbefore mentioned, as the same may be varied
without departing from the Invention, and that I make no claim to any of the
aforesaid powders used separately and distinctly from phosphate of tin, but what I
do claim is,
The use of phosphate of tin in combination with any or all of the powders herein-
before mentioned, substantially as and for the purposes described.
In witness whereof, I, the said Thomas Fletcher, have hereunto set my hand
and seal, this Twenty-fourth day of June, in the year of our Lord One
thousand eight hundred and seventy-nine.
HA
THOMAS FLETCHER. (L.S.)