A number of α-methyl-furano-flavones and their dihydro derivatives have been prepared using 7-hydroxy-8-allyl flavone derivatives. Ring closure is effected with anhydrous hydrogen bromide followed by pyridine and dehydrogenation with N-bromosuccinimide. 2-Methyl cromone derivatives have also been made. Tests with fish of select compounds indicate that dihydrofurano compounds are better poisons and an α-methyl group reduces toxicity in the furano compounds.

Cyanidin has been prepared in satisfactory yields from the acetates of (+) catechin and (-) epicatechin by monobromination with N.B.S. and subsequent treatment.

The perturbation equations for the stability of viscous flow over a concave surface have been solved only to the first approximation. The criteria for the stability has been obtained. The flow becomes unstable when the dimensionless critical parameter$$R_\theta = \sqrt {\theta /r} $$ exceeds the value 0.57 at αθ = 0.11.

This result is in good agreement with Görtler’s value.