59 8 SCIENCE PROGRESS 



published the results of experiments on the pigments present in 

 some berries, e.g. cherry, black currant, and in autumn leaves, e.g. 

 red currant, and also of his attempts to purify and isolate them. 

 For the red leaf pigments he suggested the name Erythrophyll 

 (leaf red), but pointed out that it would not be wise to use this 

 term, as the pigments of flowers and berries appeared to belong 

 to the same class. Here we see an indication of the expansion 

 of the term anthocyan to cover other than flower pigments. 



In his attempts to prepare the pure pigments, Berzelius made 

 use of the precipitation, by means of lead acetate, of the insol- 

 uble lead salts of these pigments, and of their regeneration, 

 on decomposing these compounds by means of sulphuretted 

 hydrogen. Berzelius did not obtain any pure pigments, but the 

 above-mentioned method, either as used by him, or with such 

 small modifications as the decomposition of the lead salt by 

 means of hydrochloric acid instead of with sulphuretted hydrogen, 

 has been used by a large number of later workers, though of 

 these, only Grafe (see below) obtained crystalline pigments 

 by this means. Berzelius was not of the opinion that all these 

 pigments could be looked upon as being the same blue sub- 

 stance changed by variation in the cell sap. 



The next work of interest was that of Morot (Annates des 

 Sc. nat. (3), 13, 160 (1849-50), who attempted to prepare the blue 

 pigment of the cornflower by repeated precipitation of aqueous 

 solutions by means of alcohol. He did not obtain any pure pro- 

 duct, but the method is of interest in that, improved by the use 

 of modern apparatus, it constituted the first step of the process 

 whereby Willstatter and Everest (see below) isolated the pure 

 cornflower pigment. Morot still had nitrogen containing im- 

 purities present in his products, and in the presence of nitrogen 

 saw a possible connection between this pigment and chlorophyll, 

 but he was doubtful whether the nitrogen was really a constit- 

 uent of the pigment. He described the decolourisation on stand- 

 ing in solution, which is characteristic not only of this pigment, 

 but also of nearly all anthocyans. That the decolourisation 

 observed by Morot occurred in other cases was proved by the 

 work of Fremy and Cloez (Jonm. de Ph. et de Chim. (3) 25, 249), 

 who, moreover, by allowing such a decolourised solution to 

 evaporate in the air, whereby the colour returned as the solution 

 became concentrated, showed that the pigment was not destroyed 

 by this change. They, however, looked upon the decolourisation 



