Improvements in the Composition and Manufacture of Stopping and Cement for Dental and other Purposes.
Year: 1894

page_text: Date of Application, 5th Oct., 1894
Complete Specification Left, 27th Nov., 1894-Accepted, 12th Jan, 1895
PROVISIONAL SPECIFICATION.
Improvements in the Composition and Manufacture of Stopping and
Cement for Dental and other Purposes.
I, THOMAS ROWNEY Gentleman of Reddeholm, The Park, Duffield Road
Derby, do hereby declare the nature of this invention to be as follows:-
My invention consists in the use of silica which has been assimilated by animals
oi vegetables instead of silica obtained directly or by any chemical or mechanical
process from the mineral kingdom. By preference I use kieselguhr, but silica
obtained from grasses, inshes or sponges by calcination may also be used. With
such silica I produce cements of greater hardness, tenacity & finor texture capable
of a higher polish than when other forms of silica enter into their composition.
For dental purposes I combine this silica in large proportion with the dense zinc
oxide usually sold under the name of oxyphosphate of zinc aud phosphate of zinc
& alumin neither of which preparations contain such silica.
For building & other like purposes I combine this silica with lime (in various
forms) & other matters.
Dated this Fifth day of October 1894.
Improvements in the Composition and Manufacture of Stopping and
Cement for Dental and other Purposes.
THOMAS ROWNEY, Reddeholm, The Park Derby, Gentleman, does hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
1 take any diatomaceous deposit whether fresh water or marine, or any animal
o vegetable matter, such as sponges, grasses, rushes & the leaves of plants
containing silica which has been assimilated by the living tissues of such animals &
plants. These materials I calcine at a high temperature until every particle of
organic matter 13 1emoved and then boil in nitric acid or other acid until every
soluble impurity is got d of But if I want a strong cement of dark colour I
omit the acid treatment. The residue wash with distilled water & then diy it in
a hot chamber. This residue I namo bio-silica With this bio-silica I mix by
levigation, a deuse zinc oxide such as is usually employed in making dental
cements. I also mix with it commercial zine oxide either alone or together with
the dense oxide in the proportion of one part of bio-silica to four or five parts or
more of the zinc oxide, but I do not confine myself to these proportions, vaiying
them according to the purpose for which the cement is to be used and the quality
of the bio-silica.
The mixture so obtained I name bio-silicated zinc oxide. This I make into a
paste at the time of using it with ferro phosphate of alumina prepared by dissolving

page_text: freshly precipitated protoxide of on, to saturation in a solution of phosphate of
alumina of the specific gravity 1.5.
I also combine the bio-silica and the bio-sihcated zinc oxide in the proportion of
20 per cent, with phosphate of lime, anhydrous lime lime hydrate and gypsum and
alumina either separately or with any mixture of them as cements for other
purposes, but the proportions may be varied.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
The use of bio-silica obtained from vegetable and animal tissues however
prepared as distinguished from silica obtained directly or indirectly from the
mineral kingdom by any means, either chemical or mechanical.
1 further clan the use of bio-silica in the proportion of one of it to five of ziIDC
oxide which is a "novelty," (which yields the best results), and in any greater oi
less proportion in combination with zinc oxide, phosphate of lime, anhydrous lime
lme hydrate, gypsum and alumina, either separately, or with any mixtures
of them.
I also claim the ferro phosphate of alumina made as before described, whether in
the form of crystals or as a fluid for making the mixtures described, into a paste,
but I do not claim the use of ordinary phosphate of alumina for such purpose.
Dated this 24th day of November 1894
THOMAS ROWNEY.