ENDOTHIA PIGMENTS 
347 
The alcoholic solution remaining after the acetyl derivative of the 
pigment from E. parasitica had crystallized out and had been separated 
was treated with about four volumes of water. A flocculent yellow 
precipitate was formed. This was filtered off and washed with water. 
The dry pigment was amorphous and of a bright yellow color. No 
acetyl derivative was formed even on long boiling with acetic anhydride 
and sodium acetate. When the pigment was dissolved in alcohol 
and treated with dilute alkali, the color closely approached rose dore. 
It is evidently another pigment and the properties which separate 
it from pigment A are as follows: It does not form an acetyl derivative; 
it has an entirely different color when treated with alkali; it is insoluble 
in cold petroleum ether and dissolves in cold concentrated nitric acid 
with an orange red color and is red when dissolved in cold sulphuric 
acid. It is readily distinguished from pigment B by its solubility in 
ether and nitric acid and insolubility in water and very dilute alcohol, 
also by its appearance when dry and when in acid or alkaline solution. 
This pigment, which will be referred to in this paper as pigment C is 
also found in extracts from E. fluens. Its presence has not yet been 
demonstrated in the extract from E. tropicalis. 
From the experimental work just described it is evident that there 
are at least three different pigments formed by species of this genus, 
pigment A, apparently common to all species, pigment B found in 
E. fluens and probably also in the other species having a similar 
spectral transmission of the acid alcoholic solutions and pigment C 
which is present in the two groups typified by E. fluens and E. para- 
sitica. 
It is of course quite possible that these three pigments are closely 
related chemically and may be derivatives of the same substance. 
They are similar in many particulars. All three are composed of 
carbon, hydrogen and oxygen. That is, on incineration they leave no 
ash and tests for nitrogen,^ phosphorus, sulphur and the halogens 
showed that none of these elements were present. 
The comparative solubilities of these three pigments are shown in 
Table I. These tests were all at room temperature and indicate 
whether or not the pigment is appreciably soluble in the reagent used. 
From the table it is evident that these pigments, especially pig- 
ments A and C, are readily soluble in a considerable number of organic 
8 Fresenius, C. R. Quantitative Chemical Analysis. Cohn's translation of 
the sixth German edition, 2: 4-7. 191 1. 
