Paper, 'On the action of the rays of the solar spectrum on vegetable colours' by Sir John F W [Frederick William] Herschel Letter that accompanies postscript to paper found at PT/26/12. Postscript found at PT/26/13. Illustrations for this paper have been separated from the manuscript and are found at PT/75/2/9. Subject: Physics Published in Philosophical Transactions as 'On the action of the rays of the solar spectrum on vegetable colours, and on some new photographic processes'. Written by Herschel in Collingwood [Kent, England]. Received by the Royal Society on 15 June 1842. Read 16 June 1842. Abstract published in Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London [later Proceedings of the Royal Society of London], Volume 4, 1843. 13 June 1842