The ,/3-hexenoic acid (m. p. 33-34°) gives with silver chlorate the dl-1,2-dihydroxycaproic acid (m. p. 108.5°) with 86% yield and with perbenzoic acid the df-l,2-dihydroxycaproic acid (m. p. 99.5°) with 46% yield.
Chicago, Illinois
Cr+++ in chrome alum solution was found to react slowly with the dye. The green Cr+++ reacts more rapidly than the blue; increase of temperature hastens the reaction. At room temperature, 0.10 mg. of green Cr++ + gave after fifteen minutes a color equivalent to 0.0005 mg. of aluminum, after thirty minutes 0.001 mg. of aluminum, and after eighteen hours 0.008 mg. of aluminum. It is seen that Cr+++ is but a slight source of interference under the conditions. Complete elimination of this interference is indicated by an increase in Pn dependent on the quantity of Cr+++ with, of course, a resultant decrease in over-all sensitivity of the test.Under the present conditions, the aurin reaction with aluminum is extremely delicate. A faint pink is obtained with 0.0001 mg. of aluminum, so that the sensitivity is about twenty times that reported by Yoe and Hill under alkaline conditions. Besides the elimination of fading and of carbon dioxide evolution, turbidity in the presence of foreign ions such as that observed by Yoe and Hill is also obviated.New Brunswick, New Jersey
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