IMPROVEMENTS IN TELEPHONIC APPARATUS AND IN MATERIALS THEREFOR.
Year: 1882

page_text: LETTERS PATENT to John Berger Spence of 31 Lombard Street in the city
of London and John Edlington Chaster of 28 Talbot Street Southport for an
PROVISIONAL SPECIFICATION left by the said John Berger Spence and
John Edlington Chaster at the Office of the Commissioners of Patents on the
27th November 1882.
JOHN BERGER SPENCE of 31 Lombard Street in the city of London, and JOHN
EDLINGTON CHASTER of 28 Talbot Street Southport "IMPROVEMENTS IN
TELEPHONIC APPARATUS AND IN MATERIALS THEREFOR.'
"
This invention has for its object the improvement of existing telephonic
apparatus 1 we find that certain metallic sulphides of homogeneous nature form
excellent material with which to vary passing currents in microphones and
telephones the sound being thereby largely increased without injuring materially
its distinctness. In order to make them homogeneous we prefer to fuse them and
cast them in the form required. Various sulphides pyrites or blendes will do but
as they are almost invariably not homogeneous in their natural state we find it
necessary in most cases to fuse the material The variety we have found to suit
best in our experiments hitherto consists of 32 parts by weight of sulphur to 56 of
iron fused into it so as to be homogeneous, but ordinary or inagnetic pyrites even
when contaminated with arsenic and other metals will if fused and cast without
flaws or dross be found to answer nearly as well-but the silica, carbonate of lime,
or magnesia almost always present in these materials must be eliminated or
dissolved in the mass to enable it to be available and it is better to forin the
materials synthetically and thus avoid them altogether
Phosphides, Arsenides, antimonides and selenides appear to have similar effects
when similarly treated though perhaps not to the same extent, precipitated
sulphide of iron if conglomerated by hydraulic pressure will act almost as well as
fused material but is more costly to work.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Berger Spence and John Edlington Chaster in the Great
Seal Patent Office on the 26th May 1883.
JOHN BERGER SPENCE of 31 Lombard Street in the City of London and John
EDLINGTON CHASTER of 28 Talbot Street, Southport, "IMPROVEMENTS IN
TELEPHONIC APPARATUS AND IN MATERIALS THEREFOR
33
This invention has for its object the improvement of existing telephonic
apparatus.
1 We find that certain metallic sulphides if homogeneous, form excellent
material with which to vary passing currents in microphones and telephones the
Bound being thereby largely increased without injuring materially its distinctness.
In order to make them homogeneous we prefer to fuse them and cast them in the
form required. Various sulphides pyrites or blendes will do but as they are almost
invariably not homogeneous in their natural state we find it necessary in most
cases to fuse the material. The variety we have found to suit best in our
experiments hitherto consists of 32 parts by weight of Sulphur to 56 of iron fused
into it so as to be homogeneous, but ordinary or magnetic pyrites even when
. contaminated with arsenic and other metals will if fused and cast without flaws or
dross be found to answer nearly as well, the sulphur flies off in the fusing
and the resulting fused material appears to correspond to the symbols Fe S-The
Silica, carbonate of lime, or magnesia however almost always present in natural
pyrites must be eliminated or dissolved in the mass to enable it to be available and
it is better to form the materials synthetically and thus avoid them altogether.
Precipitated Sulphide of iron if conglomerated by bydraulic pressure will act
almost as well as fused material but is more costly to work, and we find that this
precipitate when fused is the best material we have yet experimented upon for
making microphone points of contact.
Having now described our invention we claim under the Letters Patent
First The improvement in telephonic apparatus which consists in making micro-
phonic points of contact of fused metallic sulphide of iron.
Second The material substantially as herein described for varying passing currents
in telephonic apparatus
In witness We the said John Berger Spence and John Edlington Chaster
have hereunto set our hands and seals this twenty fifth day of May in
the Year of Our Lord one thousand eight hundred and eighty three
TOUN REPOED SPENCE
Gal