SECTIONAL TRANSACTIONS.— B. 309 



In dilute aqueous ammonia, however, the specific rotation changes widely with the 

 concentration of the alkali ; thus, in a 1-75 per cent, solution in 12 per cent, aqueous 

 ammonia solution gave a specific rotatory power of [a]= +8'7°. This curious 

 reversal of the sign of the rotatory power suggests that the constitution of the 

 dihydantoin changes in alkali solution to the tautomeric form 



N-CO NH-C.OH 



C I 



/\ I 

 HO.C-NH CO-N 



BUtz recognised that the spiro-dihydantoin exists in this form in its diacetyl- 

 derivative, and it is generally agreed that uric acid also assumes the enolic form in its 

 metallic salts. The present work furnishes strong confirmation of the view that the 

 numerous different types of compound containing the group -CO-NH-, which yield 

 metallic derivatives, do so in the enolic form. 



Whilst externally compensated spiro-5:5-dihydantoin is very sparingly soluble in 

 alcohol and water, its optically active components are readily soluble ; so great is 

 the difference in solubility that d-spiro-5:5-dihydantoin can be separated in an almost 

 pure state from the optically impure material recovered after part of the Z-isomeride 

 has been removed as brucine salt. On washing this mixture with cold alcohol, the 

 d-compound dissolves whilst the rfZ-substance remains undissolved. Further, on 

 mixing cold concentrated alcoholic solutions of d- and Z-isomerides the tZZ-substance 

 separates in small colourless needles ; it is thus proved that the externally com- 

 pensated substance is a true racemic compound. 



We are now studying the substitution derivatives of the spiro-5:5-dihydantoin, 

 in connection with which interesting problems in stereochemistry and tautomerism 

 obviously arise. 



Prof. F. E. Francis, Dr. T. Malkin, and Mr. S. H. Vifer.— Natural 

 Fatty Acids. 



Dr. M. NiERENSTEiN. — Pyrylium Series. 



Afternoon. 

 Visit to The Bristol Potteries. 



Visit to the works of the St. Anne's Board Mill Co. 



Friday, September 5. 



Discussion on The Present Position of the British Dyestuff Industry. 

 (Prof. A. G. Green, F.K.S. ; Prof. J. F. Thorpe, C.B.B., F.R.S. ; 

 Mr. T. Taylor ; Sir William Pope, K.B.E., F.R.S. ; Prof. G. T. 

 Morgan, O.B.E., F.R.S. ; Mr. C. J. T. Cronshaw ; Mr. J. Rogers ; 

 Mr. J. Morton ; Sir Joseph Turner ; Mr. W. J. U. Woolcock, 

 C.B.E.) 



In opening this discussion on the present position of the British dyestuffs industry 

 Prof. A. G. Green, F.R.S., continues his survey of the progress of this industry since 

 1901 when he spoke on a similar topic at the Glasgow Meeting of the British Association. 

 He outlines the deplorable position of the British enterprise in dj-es at the outbreak 

 of war in 1914, and describes the emergency measures which then had to be taken to 

 ensure adequate supplies for our country and its allies. The renaissance of the 

 British industry dates from that period. He then refers to the changes in organisation 

 which occurred during the latter part of the war period, and thus leads up to the state 

 of affairs which immediately preceded the legislative measure known as the Dyestuff? 

 (Import Regulation) Act which came into force in January 1921 to continue until 



