664 U . S. BUREAU OF CHEMISTRY NOTES. [ J . F . I .

to 3.80 mgm. per kilogram. The volatile esters and volatile acids in fifty samples, representing about thirty-four varieties, varied from 6 to 366 and from 3 to I2I mgm. per kilogram, respectively.

Anthranilic acid ester has not been found in the fruit of Vitis vinifera. The determination of this ester, therefore, appears to be of value in identifying species.

Contrary to general opinion, the volatile flavor of grapes is not contained almost wholly in the skins. Substantial proportions are found in the pulp. Nearly as much volatile flavor remains in the pomace as is contained in the expressed juices.

Anthranilic acid ester tends to disappear from grape juice which is stored. This fact may explain the deterioration in flavor of certain commercial bottled grape juices.

The anthranilic acid ester in fourteen samples of commercial bottled grape juices of unknown origin varied from o.oo to 1.35 mgm. per litre. The volatile esters in eight of these samples varied from 5 to 29 mgm. per litre.

A F I E L D M E T H O D F O R D E T E R M I N I N G T H E OIL S T R E N G T H O F SPRAYS2

By E. L. Griffin (Bureau of Chemistry) and C. H. Richardson (Bureau of Entomology).

[ABSTRACT.]

THE Babcock method for the determination of butter-fat in milk and cream is modified to give the per cent. by volume of oil in concentrated and spray-strength petroleum oil emulsions. The modified method is adaptable to emulsions containing soap, cresol, glue and probably other organic emulsifying agents, and can be used during spraying operations in the field. It is simple and can be used by non-technical men.

MODIFICATI ONS OF M E T H O D S FOR MAKING COLD-MIXED OIL EMULSIONS. '

By C. H. Richardson (Bureau of Entomology) and E. L. Griffin (Bureau of Chemistry).

[ABSTRACT.]

A COLD-MIXED lubricating oil emulsion can be made by the addition of 8 liquid ounces of crude cresylic acid, cresol U.S.P.,

* Published in J. Econ. Entomology, r 9 (June, I926) : 522--525. ' Published in J. Econ. Entomology, x9 (June, I926) : 525-529.

Nov., 1926.] U . S . BUREAU OF CHEMISTRY NOTES. 66 5

or cyclohexanol to the usual proportions of potassium fish oil soap and oil called for in the boiled emulsion formula, adjusting the water content to give about 68 per cent. oil by volume. The paste of oil, soap, and cresylic acid first obtained may be diluted at once with water to form a stock emulsion, or stored for future use. It will keep indefinitely if evaporation is prevented, but should be mixed with a little water before being poured into the spray tank. When diluted to spray strength, this emulsion has the stability and small droplet size characteristic of diluted mis- cible oils. Any petroleum oil from kerosene to lubricating oil of high viscosity can be used to prepare this emulsion. A good cold- mixed emulsion can also be made with two gallons of oil and one quart of potassium fish oil soap. The soap-oil paste may be stirred at once into 3 quarts of water to make a stock emulsion or held for future use. Such emulsions appear to be as stable as those prepared according to the usual boiled emulsion formula.

S O - C A L L E D H A B I T U A T I O N TO "ARSENIC. ''5

By Erich W. Schwartze and James C. Munch.

[ ABSTRACT. ]

THE Bureau of Chemistry undertook a series of experiments to find an answer to the question, Can habituation of man or the higher animals to arsenious oxide be obtained?

No certain habituation of cats to "arsenic " fed in increasing doses at suitable intervals could be shown. The loss of appetite and slowness of eating which developed, or which cats voluntarily induced, complicates an analysis of the data. This enables the cats to retain more food than they would had the meal been eaten at once and a portion subsequently vomited. This " pseudo " tolerance is not regarded by the investigators in any sense as a real tolerance.

Cats fed daily doses of dissolved arsenious oxide (" arsenic ") in sub-emetic concentration developed no habituation; on the con- trary, they showed a decline in appetite. They vomited once or twice early in the exper, iments, obviously from the cumulative superimposition of the effects of the sub-emetic doses, and there- after regulated the food intake, apparently to avoid the emesis.

The criterion of habituati6n has been the threshold emetic dose, which is much lower than the concentration necessary to

Published in Y. Pharma. and Exp. Therapeutics, 28 (Sept., 1926) : 351-36o. VOL. 202, No. 1211- -47