H 8.77 8.97 8.90 8.85 8.87 8.83 8.80
O 16.04

If we shake up the ether solution of bitter substance with an aqueous
solution of acetate of copper, the ether will assume a green color, and
gradually deposits a green crystalline powder, a cupreous combination
of the bitter acid. It is difficult to obtain in a pure state, as the
solutions are readily subject to slight decomposition, accompanied by a
small deposit of copper oxide. This combination is readily soluble in
alcohol, to a lesser extent in ether, and is insoluble in water.

In the course of analysis, I obtained the following figures:

C 69.4 per cent. 69.3 per cent.
H 7.95 " 7.98 "
Cu 7.20 " 7.18 "

If we suppose that the copper combines with two molecules of hop-bitter
acid, by the decomposition of one of its atoms, H, we obtain the formula
C_{50}H_{68}O_{8}Cu. This combination will contain 69.87 per cent. C,
7.91 per cent. H, and 7.33 per cent. Cu. The figures obtained do not
perfectly coincide with those calculated; it is nevertheless probable
that the formula is correct, and the combined substance analyzed was not
perfectly true.

I have already referred to the fact that solutions of hop-bitter acid,
if left standing too long, assume a yellow color, and on evaporation
leave only a yellow resinous residue. This, as its reaction shows,
evinces a complete analogy with the crystallized acid. The dark-colored
mother solution, from which the crystalline cakes of bitter acid are