Dr P. W. LATHAM, On the Composition of Albumen, and the changes Mr J. W. L. GLAISHER, On a method of deriving formulæ in Elliptic Mr E. HILL, On the effect of fluctuations in a variable, upon the mean Mr HOMERSHAM Cox, On the application of Quaternions and Grass- PAGR 169 186 188 194 197 198 Dr P. W. LATHAM, Further observations on the transformation of alcohol and on the formation of alcohol and urea in the living body 198 Dr J. B. PEARSON, On the use of large telescopes in twilight Mr A. G. GREENHILL, On the rotation of a liquid ellipsoid about an axis, not a principal axis, but lying in a principal plane. Mr A. G. GREENHILL, Note on Professor Cayley's paper on the elliptic function solution of the equation x3+y3—1=0 205 208 223 Mr A. J. C. ALLEN, Notes on solid geometry. 228 Dr J. B. PEARSON, On the use of Quartz or Rock-crystal in the objectglasses of telescopes 229 Mr A. FREEMAN, On an altazimuth constructed from the designs of the late Rev. Dr W. Pearson 234 236 Professor W. J. LEWIS, On the measurements of a bead of Platinum, by the late Professor W. H. Miller Professor W. J. LEWIS, On a crystal of Stephanite from Wheal Newton 240 Mr A. FREEMAN, Note on a table showing the time and place of the transit of any star across the prime vertical circle in latitude 52° 12′ 10′′ Cambridge: PRINTED AT THE UNIVERSITY PRESS. AND SOLD BY 245 DEIGHTON, BELL AND CO. AND MACMILLAN AND CO. CAMBRIDGE; BELL AND SONS, LONDON. PROCEEDINGS OF THE Cambridge Philosophical Society. February 6, 1882. PROFESSOR BABINGTON, VICE-PRESIDENT, IN THE CHAIR. Mr E. J. Love, St John's College, was balloted for and duly elected an Associate of the Society. The following communications were made to the Society: (1) On the Composition of Albumen, and the changes which Leucine and similar bodies undergo in the animal system, by P. W. LATHAM, M.D., Downing Professor of Medicine, Physician to Addenbrooke's Hospital. The formula by which the composition of the proteids is generally represented, viz. that of Lieberkühn*, is C72 H112 N18 O22 S Schützenberger, who devoted some three years to the analysis of egg-albumen, gives as its composition C240 H387 N65 O75 $3 These two formulæ differ chiefly in the amounts of carbon and sulphur; for multiplying the first by 3 we get To resolve such a formula into one representing the proximate constituents of a proteid seems at the first glance hopeless. The following considerations, however, give us some help in the solution of the problem: 1. Several of the products which occur in or can be obtained from the animal organism, such as lactic acid, leucine, benzoic acid, * Fownes, Manual of Chemistry, 1877, p. 625. + Annales de Chimie, 1879, p. 384. VOL. IV, PT, IV. 13 can also be obtained artificially from the cyanhydrins of the alcohols and ketones. 2. Lactic acid is produced when a muscle dies, or when it contracts, and by lactic fermentation from sugar. It can also be obtained (i) by oxidising ethylic alcohol, treating the aldehyde so obtained with hydrocyanic acid to form a cyanhydrin, and acting upon this with acids or alkalis (ii) By converting ethene alcohol or glycol into a cyanhydrin and boiling with acids or alkalis 2. Leucine is very largely diffused in the animal organism, and may be obtained by various processes from albumen, flesh, gelatine, casein, &c.‡ By oxidising amylic alcohol with potassium chromate and sulphuric acid, and distilling, we obtain amylic or valerianic aldehyde §— Mixed with aqueous ammonia the aldehyde is converted into valeral ammonia, and this digested with hydrocyanic acid and hydrochloric acid is converted into leucine * Fownes, Manual, p. 319. Watts, Dictionary, Vol. III. p. 574. Fownes, p. 319. |