The residue was poured into 20 ml. of cold, dry ethyl ether with vigorous stirring. The pink precipitate which formed, was collected on a filter, washed with 20 ml. cold, dry ethyl ether and dried in the absence of air at 25°; yield, 150 mg. The brominated histidine decomposed rapidly on exposure to air. It was soluble in water, ethanol and acetic acid, insoluble in ethyl ether. It was acid to methyl red and reacted with aqueous silver nitrate.Anal. Caled, for C«HsOjNjBr-2HBr: total Br, 60.57; Br as HBr, 5.95 ml. 0.1 N AgNOa per 100 mg. Found: total Br, 57.8; Br as HBr, 5.40 ml. 0.1 N AgNOa per 100 mg. These data are summarized in Table II.Preparation of Bromozein Hydrobromide.-Ten grams of bromine in 500 ml. of glacial acetic acid was added slowly to a solution of 50 g. of zein in 450 ml. of 90% acetic acid. The reaction mixture was allowed to stand twenty-four hours at 25°in diffuse daylight and then poured slowly into 7 liters of dry ethyl ether with vigorous stirring. The white precipitate which formed, was collected on a filter, washed with 3 to 4 liters of dry ethyl ether and dried forty-eight hours at 50°; yield, 55.00 g. This solid was soluble in 90% acetic acid and 70% ethanol. It reacted with sodium hydroxide and silver nitrate in ethanol and liberated iodine from potassium iodide in acetic acid. An accelerated gelation test of bromozein hydrobromide in 70% ethanol showed only a slight tendency toward gel formation.

There have been isolated and definitely identified from petroleum six naphthenic acids: 3,3,4-trimethylcyclopentaneacetic,3 cyclopentanecarboxylic,4 cyclopentaneacetic,4 3-methylcyclopentaneacetic,4 dl -1,2,2-trimethylcyclopentane-carboxylic5 and solid 4-methylcyclohexanecar-boxylic6 acids. Since this manuscript was prepared, however, Buchman and Sargent have been able to show that von Braun's acid is not 3,3,4trimethylcyclopentaneacetic acid.Results reported in this paper were obtained in a continuation of the petroleum acid research on a complex mixture of acids obtained from the sodium carbonate washing of Signal Hill, California, straight run gasoline.5,7Since Hancock was able to isolate camphonanic acid from the higher boiling acids through the fact that it is not esterified by treatment with methanol and dry hydrochloric acid, it seemed possible that other unesterifiable acids might be present in the acids containing eight to ten carbon atoms. Accordingly various fractions of acids boiling in the C § to Cjo range were carefully fractionated and then each fraction was separately heated for twenty-four hours with methanol and dry hydrogen chloride. These operations yielded a total of 800 g. of unesterified acids. By subjecting 22 liters of still higher boiling stored material to the same treatment another 2030 g. of unesterified material was obtained.Careful fractionation of these acids yielded 400 cc. of esters that had been dissolved in the acids, 700 cc. of liquid acids and 940 g. of acids that solidified in the receiver or in the condenser. Fractional liberation of these solid acids from their sodium salts yielded 280 g. of camphonanic acid, 500 g. of another solid acid melting 70-80°,(1) From theses submitted by Billie Shive, Joe Horeczy and George Wash in partial fulfillment of requirements for the Doctor of Philosophy degree, June, 1941.

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