Paper, 'Note on the constitution of chlorophyll' by [Henry] Edward Schunck

Description

Schunck writes: 'An examination of some products derived from chlorophyll, which has occupied me for some time, has led to the question of the true nature and constitution of chlorophyll, a question on which widely different opinions prevail. Without entering into matters which concern the physiologist only, it may be said that to the chemist chlorophyll is simply an organic colouring-matter, the substance to which the green colour of leaves and other parts of plants is due. Now colouring-matters are of three kinds. To the first class belong such as occur ready formed and in a free state in vegetable and animal organisms, such as the colouring-matters of turmeric and safflower. The second class comprises those that are formed from colourless chromogens by the combined action of alkalis and oxygen, the colouring-matters of log-wood and archil being well-known examples of this class. These colouring-matters change rapidly when exposed to the further action of oxygen in the presence of alkali, but are quite stable when in contact with acids. The third class consists glucosides, bodies which do not undergo any considerable change under the influence of alkalis, but are rapidly decomposed when acted on by acids or ferments, yielding, on the one hand, some kind of glucose, and, on the other, substances in which the tinctorial properties of the parent substance are much more pronounced. To this division belong the colouring-matters of madder, quercitron, cochineal. &c.'

Annotations in ink.

Subject: Biology / Chemistry

Received 6 December 1883. Read 20 December 1883.

A version of this paper was published in volume 36 of the Proceedings of the Royal Society as 'Note on the constitution of chlorophyll'.

Reference number

PP/4/16

Earliest possible date

1883

Physical description

Ink on paper

Page extent

6 pages

Format

Manuscript