2 6 6 U . S . B U R E A U OF C H E M I S T R Y NOTES. [J. F. I.

2 3 per cent. of sa tura ted acids and 72.5 per cent. of unsa tu ra ted acids as de te rmined by the lead-sal t -e ther method. T h e iodine value ( H a n u s ) of the unsa tu ra ted acids was 142.2, th.e saponifi- cat ion n u m b e r was 199.4, and the mean molecular weight was 281. 3 .

In addi t ion to the separa t ion and identification of stearic and arachidic acids, a small a m o u n t of myr is t ic ~icid was found which has not been pr.eviously repor ted as occur r ing in cot tonseed oil.

The fol lowing table gives the percentages of the acids found f r o m which the cor responding glycerides were calculated:

Acid. Per cent in Original Per cent in OriginaI Oil Acids. Oil Glycerides.

Myr i s t i c . . . . . . . . . . . . . . . . . . . . . . o.32 0.34 Palmitic . . . . . . . . . . . . . . . . . . . . . . i9.io 20.04 Stearic . . . . . . . . . . . . . . . . . . . . . . . 1.9o 1.96 Arachidic . . . . . . . . . . . . . . . . . . . . . . 56 .58 Oleic . . . . . . . . . . . . . . . . . . . . . . . . . 33.i5 35.17 Linolic . . . . . . . . . . . . . . . . . . . . . . . 39.35 41.74

Galvanomagne t i c Effec t Para l le l to the L ines of Force and Perpend icu la r to the Current . LA Rosa and A. SELLERIO. (Comp- tes Rendus, June 14, I92O. ) - - I f an electric cur rent flows a long a sheet of b i smuth , the ends of two wires joined to a g a l v a n o m e t e r m a y be put in contac t wi th two points on the b i smuth so located tha t they are at the same potential . In this case no cur ren t flows th rough the ins t rument . If, now, a s t rong magne t ic field is ap- plied wi th its lines of force at r ight angles to the sheet of b ismuth , a cur rent shows itself in the ga lvanomete r . T h e magne t i c field has d is tor ted the lines of flow of the cur rent (Hal l effect) .

The two exper imen te r s placed a cyl inder of b i smuth be tween the poles of a Wei s s e l ec t romagne t wi th its axis parallel to the lines of force. A current was sent f rom one side of the cyl inder to the other and the ends of the wires f rom the g a l v a n o m e t e r were soldered to points on the end of the cyl inder which were at the same potential , when the magne t i c field was absent. W h e n the field was excited there was a p e r m a n e n t deflection of the gal- vanomete r , which was reversed in direction when the field was reversed. T h e deflections in the direct ions were by no means alike in size. T h e au thors conjec ture tha t there are two effects super imposed , one of which reverses wi th the field while the o ther does not. The difference be tween this new phenomenon and the Hal l effect is in this, tha t in the la t ter the effect is perpendicular to the direction of the current , while in the newly discovered effect it is mani fes ted a long the magne t i c lines of force.

G. F. S.