SCIENTIFIC COMMITTEE, MARCH 8. 



xxxi 



Pigments in Bean seeds. — Mr. E. A. Bunyard, having examined 

 the pigments in the seeds of the Beans shown on January 11, wrote 

 saying that they exhibited seven distinct tints of brown, two shades 

 of green, one black, and one blue-black. 



" All the tints of brown are due to one pigment, which is insoluble 

 in carbon bisulphide water, alcohol, ether, acids, and alum, but soluble 

 in an aqueous solution of ammonia. A flocculent precipitate is thrown 

 down from this solution by acetate of lead, and a strong black colour 

 formed when treated with ferrous sulphate. 



It seems probable, therefore, that the pigment is a tannin, but the 

 small amount of material renders it impossible to affirm this with any 

 accuracy. It is apparent that they are merely quantitative differences 

 of the same pigment. The Beans are referred to under numbers, as 

 No. 1, etc. ; the colours {Code des Couleurs) as C. 100, etc. 



Bean No. 1 is, for instance, a near approach to C. 107, and the 

 pigment, in a state of purity, would probably be between the ' standard 

 colours ' Nos. 0. 101 and 126. 



Nos. 9, 6, 3 are closely matched by 0. 107, 113, 143 respectively, 

 and the parent Beans show the pigment much diluted in 0. 128 D. 



No. 8 has, however, a distinct green tinge. In this, microscopical 

 examination reveals the pigment in a finely granulated condition, which 

 causes, of course, greater light absorption than when in a liquid or 

 semi-liquid condition. 0. 167 gives this tint well. 



No. 2 might at first be considered black, but a careful examination 

 reveals its greenish hue, due to a large amount of the same pigment, 

 also very finely granulated. No. 11, an apparent black, reveals the 

 same condition. The colour in these two cases is soluble in ammonia, 

 and gives a solution identical with that extracted from No. 1. 



The only other case I have met where a yellow pigment strongly 

 concentrated gives an appearance of black is the case of Coelogyne 

 pandurata, in which the black lines are formed of highly concentrated 

 yellow pigment. 



Nos. 8, 2, and 11, in which the pigment is much granulated, is 

 paralleled by the dark chocolate varieties of Sweet Peas. In these the 

 anthocyan sap is deposited in dense granules instead of being in liquid 

 form, and the very dark shades are thus produced. 



No. 10 is of a blue-black tint, not represented in the Code, and is 

 due to a strong concentration of an anthocyan pigment. The well- 

 known dwarf Bean * Negro Largo ' is coloured with the same pigment. 

 The limited material m.ade it impossible to ascertain in which division 

 of the anthocyans it should be placed." 



Wood alleged to prevent iron rusting. — Mr. Holmes, F.L.S., re- 

 ported that he had examined the wood shown by Dr. Voelcker, and 

 found it to be from a Coniferous tree which Mr. Herbert Stone, P.L.S., 

 suggested might be an Agathis ; he had not seen it before, however. 

 Mr. Holmes could suggest no reason why a decoction of the wood 

 should prevent rusting. It appears to contain resin, but that is in- 



