Galina
Dunstan's process is a secret. If you want to do it you buy the kit. So far
as I know the rest is speculation.
Amateur Photographer is not the kind of magazine that I have here or can
readily access. However I think there may be some people on the list who
have actually used the kit, so perhaps someone will give more details.
Cassell's cyclopaedia says that Heliochromy was the name given by Niepce de
St Victor to his method of colour photography discovered in 1853, but now
(1911) applied to all such processes.
He used a film of silver chloride on a silver coated plate. "Various methods
were employed to chlorise the plate, one being to dip them in a weak
solution of sodium hypochlorite (sg 1.35) until of a bright , pinkish hue.
The plates were then covered with a solution of dextrine saturated with lead
chloride, dried, and subsequently submitted to the action of heat. Rather
long exposures were required in the camera, the plate being then again
heated to render the resulting pictures a little less fugitive. Some vivid
colour reproductions were obtained, which unfortunately quickly faded, since
no means of fixing could be found. A slight access of stability was secured
by covering the plate with an alcoholic solution of gum benzoin."
Heliography, as was pointed out recently, was an early name for photography.
Peter Marshall
On Fixing Shadows, Dragonfire and elsewhere:
http://faraday.clas.virginia.edu/~ds8s/
Family Pictures & Gay Pride: http://www.dragonfire.net/~gallery/
and: http://www.speltlib.demon.co.uk/