iandol on wed 16 feb 00
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My impression is that recipes call for Black Copper Oxide
To begin with, Copper carbonate as CuCO3, according to my chem text, is an
unknown substance . The material we buy is derived from Malachite and is the
Basic Carbonate CuCO3.Cu(OH)2 with a molecular weight of 221
So, if substituting one part green carbonate equals 0.68 parts black oxide
equals 0.34 parts red oxide.
Or one part black oxide equals 1.55 parts green carbonate equals 0.56 parts =
red
oxide.
Or one part red oxide equals 2.88 parts green basic carbonate equals 1.80 =
parts
black oxide.
BUT (caveat lector), please note that these values only compare the =
molecular
weights of the three compounds so substitution may not give the predicted
results because I have ignored the fact that black oxide has one atom of =
copper
per molecule whereas both green basic carbonate and red oxide have two atoms=
of
copper per molecule. So it might be interpreted that with two atoms of =
copper
they are twice as strong in their colouring power as black copper oxide if =
it is
the copper ions which give the colour.
Now experiment.
Ivor.
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