Robert Adamson provided the technical input to
the partnership. He is known to have experimented with his chemicals.
Typically three different photographs might be taken of a subject to
increas the chance of getting a successful result, both artistically and
technically. On at least one occasion the three prints from a sitting are
known to have been processed in different chemicals.
[Sara Stevenson, September 2004]
Neither Hill nor Adamson commented on the chemicals or
process used to produce their chemicals. There has been speculation that
Adamson might have had a 'secret' ingredient in his chemistry. Hill
remarked on one occasion: "Mr
Adamson thinks he knows some things that others do not."
The Royal Scottish
Museum is carrying out a non-destructive analysis of some of Hill &
Adamson's early images in order to discover how they were created. To
date [September 2004]
the results suggest that Adamson experimented with different chemicals;
but no secret ingredient has been found.
Most of the Hill & Adamson calotypes were
produced between 1843 and 1846. Robert Adamson returned to St Andrews in
ill health in 1847, and died in early 1848, aged twenty-six.