Observations in the copper chloride crystallisation: from the "protein-model" for"copper chloride afterimage
François Schweizer, Jens-Otto Andersen und Jens Laursen
Summary
The starting point for the research presented here is Pfeiffer’s postulate that
copper chloride crystallisation of a blood sample generates a ‘protein pattern’
which is supposed to contain the essential elements of the crystallisation picture
that appears later. In the same way, when crystallising plant extracts, Engqvist
interpreted a fine water-insoluble residue observed on the surface of the glass, after
washing off the crystals, as the ‘protein pattern’, showing a representation of the
crystallisation picture.
In the present study preliminary experiments to demonstrate protein-containing
compounds with simple staining techniques (Fuchsin S) did not produce the
expected results at first. However, surprisingly, they did show the presence of
three different crystal types in the copper chloride crystallisation pictures, when
applying plant extracts and gelatin as additives:
(a) primary crystals in the form of needles that are readily water-soluble and stained
by Fuchsin S;
(b) secondary crystals present with a 50–80% coverage of the area of the glass
plate with primary needles; these are insoluble in water and are not stained
by Fuchsin S; they are present as largely opaque, very small and thin-layered
crystal patterns which appear along the edges of the primary crystal needles
at their contact zone with the glass surface;
(c) tertiary crystals, so-called fine structures, mostly in a non-linear form, which
appear in the last phase of the crystallisation; they are not soluble in water and
are not stained by Fuchsin S.
In order to examine the chemical and crystallographic nature of the three crystal
types, experiments were carried out using scanning electron microscopy, X-ray
diffraction analysis and X-ray flourescence analysis. These showed that the primary
crystals were completely identical to the original substance copper (II) chloride
dihydrate (CuCl2 ∙ 2H2O). As opposed to these the secondary and tertiary crystals
comprised water insoluble basic copper chloride compounds, for the most part
identifiable as atacamite (2CuCl2 ∙ 5Cu(OH)2 ∙ 2H2O) with smaller amounts of
anthonite (Cu(OH,Cl) ∙ 2H2O). It is not yet possible to give the exact reasons for
these changes.
Thus in our experiments we were not able to find any evidence of a ‘protein
pattern’ (Vorbild), based on crystallisation of copper chloride with plant extracts or
gelatin as additives. On the other hand, during crystallisation a ‘negative picture’ of the
actual crystallisation picture arises through the separation of water insoluble secondary
and tertiary crystals. We call this the ‘copper chloride after-image’ (Nachbild).