804 Wisconsin Academy of Sciences , Arts, and Letters. 
Tetrahy dr oxides. 
Pelaogonidin. 
According to Willstaetter pelargonidin chloride, the oxonium 
salt of pelargonidin, is probably represented by formula I. 
given below, though he also recognizes the possibility of its being 
represented by formula II. Willstaetter prefers the first fomula 
because he regards the second as the structural formula of a 
fiavone derivative. 
Pelargonidin exists in the blossoms of the red geranium, 
pelargonium zonale, combined with two molecules of glucose as 
the glucoside pelargonin. 
The geranium pigment was isolated by Griffiths 1 from the 
blossoms of the red geranium in 1903. Griffiths decided that 
the pigment has the formula C 15 H ia 0 6 and that it forms a red 
diacetyl derivative. 
In 1908 Wenzell 2 again isolated the crystalline red pigment 
from the flowers of Pelargonium zonale, but he made no chemi¬ 
cal study of the compound. 
During the winter of 1911-1912 the writer, having access to 
large quantities of geranium blossoms, again isolated the red 
crystalline pigment. The substance crystallized in fine needle 
1 Ber., 36, p. 3956. 
2 Pacific Pharmacist, 1908. 
