Royal Society. 385 



In the course of these investigations the authors were led to 

 examine* the acids contained in gum benzoin. They found that 

 benzoic acid is not contained in all varieties of the resin. In 

 some cases, especially in the benzoin from Sumatra, an acid was 

 found which crystallized differently from benzoic acid, and melted 

 under hot water to a clear oil, yet by oxidation yielded oil of 

 bitter almonds. This acid they believe to be identical with the 

 toluylic acid obtained by Strecker from vulpic acidf. 



LIII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from p. 326.] 



February 23, 1860. — Sir Benjamin C. Brodie, Bart., President, 

 in the Chair. 

 rpiIE following communications were read : — 

 •*- " On the Lines of the Solar Spectrum." By Sir David Brew- 

 ster, K.H., D.C.L., F.R.S., and Dr. J. H. Gladstone, F.R.S. 



In a paper in the Transactions of the Royal Society of Edinburgh 

 for 1833, Sir David Brewster stated that he had examined the lines 

 of the solar spectrum, and those produced by the intervention of 

 nitrous acid gas, and had delineated them on a scale four times greater, 

 and in some parts twelve times greater than that employed in the 

 beautiful map of Fraunhofer. None of these drawings, however, were 

 published at the time ; they were increased by frequent observations 

 continued through succeeding years ; and now having been collated, 

 arranged, and added to by Dr. Gladstone, they form the diagrams 

 accompanying this paper. 



The figures consist of — 



1st. A map of the whole spectrum 58 inches long, and exhibiting 

 about 1000 lines and bands. This map includes a great prolongation 

 of the spectrum at the least refrangible end, before A, with a series 

 of bands and lines not hitherto described. 



2nd, 3rd, 4th, and 5th. Enlarged delineations of the portions of 

 the spectrum between A and B, and between E and F, exhibiting 

 additional lines, with still more magnified views of the groups a and b. 



6th. A map of the two extremities of the solar spectrum as observed 

 by Dr. Gladstone about noon-day at midsummer, consequently when 

 the sun was at its greatest altitude. This shows several bands between 

 A and B, and a series of lines in the lavender rays extending as far 

 as M. Becquerel's N, and corresponding evidently with the maps 

 published by him and by Professor Stokes, with the addition of finer 

 lines. Yet this map represents the extreme spaces of the spectrum 

 where there is no effect on the organ of vision, while that of M. 

 Becquerel represents the want of chemical action, and that of Pro- 

 fessor Stokes the absence of fluorescent power. 



* Liebig's Annalen, July 1860. 

 f Phil. Mag. vol. xix. p. 211. . . 



