1248
Although his name usually follows that of William
Blanchard Bolton in histories of photography—‘Bolton
and Sayce’ being given joint credit—Bolton himself ac-
knowledged that it was Sayce’s understanding of chem-
istry which drove the development of photography’s
fi rst true emulsion.
Sayce’s quest for an emulsion which could simply be
poured on to a plate and then exposed clearly places the
genesis of the idea in the wet collodion era. From initial
experiments in 1859, it took fi ve years of development
before the announcement of a working collodio-bromide
emulsion in 1864.
The emulsifi cation of silver bromide in collodion
removed the need for the separate silver nitrate bath,
and was the forerunner of all the dry plate emulsion
technology which followed. For several years, Sayce’s
discovery was known as the Liverpool Process.
Always an amateur photographer, Sayce was a
founder member of the Liverpool Amateur Photographic
Association, and one of the instigators of the fi rst In-
ternational Photographic Exhibition held in Liverpool
in 1888.
John Hannavy
SCHAEFER, ADOLPH (c. 1820–1853)
Dutch photographer
Started original as a painter and according an advertise-
ment in the Journal of The Hague in the Netherlands he
worked there as a photographer from January 1st until
the 14, 1843. He was befriended with Philipp Franz von
Siebel who wrote at Leiden on May 1, 1843, a letter of
recommendation to King William II of the Netherlands
to ask the King if Schaefer could work in the Indonesia
to work for the Ministry of Colonies to photograph the
historical buildings and places for the government. In
1844 he traveled to Indonesia to replace Jurriaan Mun-
nick, as the Dutch Government was not pleased with
the results of Munnick’s work.
Before he left he bought on November 3, 1843,
photographic equipment from Hottinguer & Comp. in
Paris for for 8882 Dutch guilders.
After his arrival Schaefer made more then 5000 pic-
tures of many Indonesian monuments and geological
places in the West Indies in order of the Dutch Govern-
ment. He used daguerreotype and later albumin types.
Most of his work in preserved at the Tropical Institute
of Amsterdam, some is preserved in the collection of
art at the Rijksmuseum in Amsterdam. In 1849 Schaefer
opened a studio in Semarang on the Isle of Java and also
gave lessons in photography.
After this time Schaefer disappeared. It could be
the result of his debt of 6073,53 guilders to the Dutch
Government.
In Dresden a men named Schaefer died in 1853,
leaving behind a widow and a son.
Petra NotenboomSCHEELE, CARL WILHELM
(1742–1786)
Swiss chemist
The chemist Carl Wilhelm Scheele was born in Stral-
sund, then part of Sweden, now Germany, and was one
of a number of eminent scientists whose work predicted
and laid the foundations for photography. His research
in 1777 into the blackening effect of light on silver
salts confi rmed the earlier fi ndings of Johann Heinrich
Schultze, and progressed scientifi c understanding of
what would become photographic chemistry.
Scheele’s signifi cant discovery was that the blacken-
ing effect of light on silver chloride—he had isolated
and identifi ed the element chlorine in 1774—was due
to chemical reduction, and that the result of that re-
duction was black silver metal. His recognition that
silver chloride blackened more quickly when exposed
to light at the blue and violet end of the spectrum was
a signifi cant contribution toward understanding that
spectral sensitivity.
In so doing, he coined the expression ‘chemical rays’
to denote those wavelengths of light which has actinic
properties.
That ammonia dissolved silver chloride was already
known to chemists, but Scheele’s application of that
knowledge to remove the silver chloride which had
not been affected by exposure to light predicted the
‘fi xing’ process upon which permanent photography
would later depend.
He is credited with the identifi cation of citric, malic,
oxalic and gallic acids—the last also a key chemical in
early photography—and was the fi rst to recognise that
air is predominantly made up of two gases, oxygen and
nitrogen.
John HannavySCHLAGINTWEIT, HERMANN
(1826–1882); ADOLPH (1829–1857) AND
ROBERT (1833–1885)
German explorers and scholars
The fi ve Schlagintweit brothers—Hermann, Adolph,
Eduard (1831–1866), wrote an account of the Spanish
expedition to Morocco in 1859–60, Robert and Emil
(1835–1904), and specialized in Tibetan studies—also
worked in Europe and Asia. Hermann’s fi rst scientifi c
mission, in association with his brother Adolph, was
conducted in the Alps between 1846 and 1848. Subse-