1903.] Group of Yellow Colouring Matters. 173 



taken place in the carotin while within the root. From the extract of 

 the pigment prepared by boiling the grated root with alcohol, the 

 carotin crystallises out on cooling, but a larger yield is obtained from 

 the juice of the grated root, which contains the majority of the carotin 

 in suspension, from which on drying it can be dissolved in ether and 

 recrystallised in the same form of crystals as chrysophyll. There is a 

 certain amount of those colouring matters present which obscure the 

 violet and ultra-violet, but the majority of the total pigment appears 

 to consist of carotin alone. 



The pigment of the tomato (Lycopersicum esculentum) is interesting in 

 so much as it consists of a crystalline substance not before described, I 

 believe, and which gives a very characteristic spectrum of similar 

 character to the other xanthophylls and from its reactions appears to 

 be of similar constitution. The tomatoes were first boiled with water 

 which extracted a little yellow colouring matter, the watery extract 

 filtered off and the pulp and skin washed with cold alcohol and the 

 red pigment extracted with boiling alcohol, in which it is not easily 

 soluble and which takes some time to extract the whole. A deep 

 orange-coloured extract is obtained, from which on cooling a rich red 

 deposit forms which is sparingly soluble in alcohol. In ether the 

 deposit dissolves readily, and on slow evaporation deep-red crystalline 

 needles form which can be purified by recrystallising from ether. If 

 the pulp and skin be first dried and the pigment extracted with ether 

 in the cold, which takes some days, the same substance crystallises out 

 on slow evaporation. The crystals are with difficulty soluble in boiling 

 alcohol from which they crystallise out on standing, they are not so 

 soluble in ether as chrysophyll neither have they the metallic lustre 

 of the latter ; in alcohol and ether their solutions are orange, but in 

 carbon-bisulphide, in which they are easily soluble, the colour is reddish- 

 pink, due to the shifting of the bands in this solvent considerably 

 towards the red. They dissolve in hot glacial acetic acid giving pale 

 yellow solutions, but spectroscopic examination shows in contra- 

 distinction to chrysophyll that this substance is acted upon by the acid 

 during solution, producing another colouring matter similar to that 

 formed by the action of strong acids upon its alcoholic solutions. In 

 alkalies the crystals are insoluble. Like chrysophyll they dissolve in 

 concentrated H. 2 S0 4 , producing a deep Prussian-blue solution which 

 soon changes to purple and then brown. HNOs causes immediate 

 decomposition and HC1 has no action. With a drop of concentrated 

 H2S04 and HNOs the same colour reactions are produced as with 

 chrysophyll. It is not a stable substance, and exposed to the air in 

 the absence of light it is decomposed in the course of a few weeks. 



The absorption spectrum is a very distinctive and definite one 

 of three bands considerably less refrangible in position than those 

 of chrysophyll, the first one being situated in the green (Plate 7, 



