Graphs, accuracy of calculated zenith distances and relation of chemical action to sun's zenith distances by unknown artist Plate 45, figures 9-10 showing a graph of the accuracy of calculated zenith distances and a graph of the relation of chemical action to the sun's zenith distance. Inscribed with publication and plate details. Not signed. The manuscript for this paper is wanting. Subject: Physics / Chemistry Published in Philosophical Transactions as part of paper titled 'Photo-chemical researches.—Part IV' by Robert Wilhelm Bunsen and Henry Enfield Roscoe. Received and read by the Royal Society on 26 May 1859. [1859]