This work was undertaken in order to develop a convenient and reliable method for the determination of phthalate esters in propellants. The method described is based upon a titanous chloride reduction of nitroesters and nitroaromatic bodies, which allows a separation of phthalate esters, by a petroleum ether extraction, and their volumetric determination.This method has been applied to the determination of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diamyl phthalate, and diphenyl phthalate, in the presence of nitroglycerin, dinitro toluene, dipheny lamine, ethyl centralite, and ethyl acetate.

chlorate is added to the warm solution after the expulsion of the hydrogen sulfide.A blank should be run using the same amounts of reagents and acid as for the sample.This procedure was used for the determination of antimony in samples containing pure antimony, antimony mixed with indium oxide, antimony mixed with indium antimonide, and pure indium antimonide. Spectrographically pure antimony was obtained from Johnson, Matthey and Co., Ltd.; indium oxide was prepared in the laboratory from high purity metal and examined spectrographically; indium antimonide (Midway Laboratory) was melted in vacuo, remelted in argon, and then finely ground in a diamond mortar. The samples were prepared to give approximately 200-mg. quantities of antimony, and the latter was determined by the iodometric method, using a color end point and a potentiometric titration. RELIABILITY OF METHODIndium does not interfere. The theoretical percentage of antimony for the formula InSb is 51.48; a value of 51.44 was obtained by potentiometric titration and 50.99 by color end point (Table I). This difference of nearly 1% may be the result of personal sensitivity to the color change, for it was difficult to determine the end point by visual observation.Titrating potentiometrically, the accuracy of the method is within 0.2%. The spread in the results for the determination of antimony in indium antimonide is believed to be due to inhomogeneity of the sample.

Mixtures of potassium perchlorate with some combustible substances have been heated in sealed test‐tubes and their ‘explosion temperatures’, time‐lag' of explosion and ‘critical’ mass/volume ratio ‘determined’. The relation between the explosion temperature and the chemical character of the substance mixed with potassium perchlorate was investigated. Influence of other factors on the ‘explosion temperature’ and on the ‘time lag’ of explosion was also examined. The possible mechanism of the observed low‐temperature explosions has been discussed.