Paper, 'Contributions to the chemistry of chlorophyll, No IV' by [Henry] Edward Schunck Schunck writes: 'In Parts I [see PP/7/13] and III [see PP/12/31] of this memoir I gave an account of the action of aqueous alkalis on phyllocyanin, and of the products thereby formed. By the action of caustic alkali in a state of fusion phyllocyanin undergoes a more profound decomposition, leading to the formation of several products, one of which I shall now describe.' Annotations in pencil and ink. Includes one diagram of an absorption spectra. Subject: Chemistry / Biology Received 16 June 1891. Read 18 June 1891. A version of this paper was published in volume 50 of the Proceedings of the Royal Society as 'Contributions to the chemistry of chlorophyll'. 1891