THOMAS
,
SIDNEY GILCHRIST
(
1850
-
1885
),
metallurgist and inventor
;
b.
16 April 1850
at
Canonbury
,
London
, son of
William
Thomas
(
1808
-
1867
), a
Welshman
in the solicitors' department
of the
Inland Revenue office
,
London
, and his wife
Melicent
(
Gilchrist
)
; for the connection of
William
Thomas
with the parish of
Llanafan, Cards.
(and other parts of
Wales
), see the biography by the
inventor
' sister,
Lilian Gilchrist
Thompson
, and the
Cambrian News
article cited in the bibliography below. Educated at
Dulwich College
which, however, he had to leave at the age of 17 because of the death of his father, he began to earn his livelihood as
teacher
in an
Essex
school and afterwards (
from 1867
) as
clerk
at
Marlborough Street (London) Police Court
; a little later he was transferred to the
Thames Police Court
. This clerkship he continued to hold for many years, devoting his evenings and most of his other leisure to attending science classes and to experimentation in an endeavour, from about
1870
, to
discover a method of de-phosphorising the pig-iron which was used in the manufacture of steel
in the
Bessemer ‘converter.’
In both the
Bessemer
and
Siemens-Martin processes
, owing to the lack of a method of de-phosphorising the pig-iron which was used, the resultant steel was brittle;
Sir
Henry
Bessemer
and other experimentalists spent years in an attempt to overcome the difficulty. Towards the end of
1875
Thomas
succeeded in reaching a provisional solution (details in
D.N.B.
). He communicated the details to his cousin
Percy
Gilchrist
, then
chemist to a large iron-works
at
Blaenavon, Mon.
, and both men conducted further experiments. In
1878
Thomas
announced at a meeting of the
Iron and Steel Institute of Great Britain
‘that he had
successfully dephosphorised iron in the Bessemer converter
.’ He took out his first patent in May of that year, and others subsequently. The solution was immediately made use of both in
Great Britain
and abroad with the result that there was a large increase in steel production. There was, however, a large increase in the production of the ‘slag’ that was formed in the ‘converter’ during the process of steel making and
Thomas
discovered, after experimentation, that this ‘slag’ which, because his process came to be known as ‘basic,’ came itself to be known as ‘basic slag,’ was a most useful soil fertiliser. The
inventor
who, in
1879
, had resigned his
clerkship
and had, as the result of his invention and the commercial use of the ‘basic slag,’ become very rich, found, however, that his health had been undermined and the remaining few years of his short life were spent largely in the pursuit of health. He d. at
Paris
,
1 Feb. 1885
, and was buried at
Passy
. He was unmarried. The large fortune which he had accumulated was left by him on trust to his sister to be devoted, as to the greater part of it, for
philanthropic purposes
.
Bibliography:
-
Oxford Dictionary of National
Biography
;
-
R. W. Burnie
,
Memoir and Letters of Sidney Gilchrist
Thomas, inventor
, London, 1891
,
1891
;
-
Lilian Gilchrist Thompson
(
née
Thomas),
Sidney Gilchrist Thomas An Invention and its
Consequences
, London, 1940
(London,
1940
);
-
The Times
,
15 April 1950
;
-
R. Osborne Jones
, ‘Noted Inventor … Cardiganshire man's remarkable career,’in
The Cambrian News
,
12 May 1950
.
Author:
Sir William Llewelyn Davies, M.A., LL.D., F.S.A. (1887-1952),
Aberystwyth
