384 U . S . BUREAU OF CHEMISTRY NOTES. lJ. F. 1.

receiving the bran. Their gain in weight per gin. of protein eaten (NX 5.7) was o.88 gin. Although the bran ration was very efficient for the promotion of growth in young rats during the first fifteen or sixteen weeks, for the subsequent forty-eight weeks only little better than maintenance of body-weight resulted.

Rats fed the bran diet produced offspring, but they had little success in rearing thenL Fecundity was low.

S U B S T A N C E S W H I C H A F F E C T P H O T O G R A P H I C P L A T E S IN T H E DARK.-"

By George L. Keenan.

[A~ST~Cr.]

THE effect which some substances have on photographic plates in the dark has been studied and a comprehensive review of the literature made. Experiments conducted in the Bureau of Chemistry and also carried on by previous workers showed that emanations proceeding from the active substances were actually responsible for the results obtained. It seemed evident that both oxygen and moisture had to be present to produce a darkening of the plate. As hydrogen peroxide could not be pro- duced in their absence, the view that this compound is the active agent seems inescapable. However, these considerations do not prove that hydrogen peroxide is the only substance that is active.

C O N S T I T U E N T S OF C R U D E C O T T O N S E E D OIL, P A L M I T I N , D I - P A L M I T I N , AND P H Y T O S T E R O L I N E . ~

By G. S. Jamieson.

[ABSTRACT. ]

THE alcohol-soluble portion of the settlings which separate from clear, crude cottonseed oil has been studied further. Although the oil investigated had stood in the laboratory for about three years before the settlings were removed for the inves- tigation, it was free from rancidity and in excellent condition.

Palmitin, amounting to about 2 5 per cent., and di-palmitin, amounting to about i per cent. of the total settlings, were iso-

2 Published in Chemical Reviews, 3: 95-Ill, April, 1926. 3 Published in the Jolw. Oil and Fat Ind.. 3, No. 5. May, 1926.