wave length examined, with the possible exception of 2894 A.3. The activation by 2894 Á. appears to be intermediate between that of 2967 Á. and the other wave lengths tested.4. No demonstrable antirachitic properties were produced by irradiation of 7-dehydrocholesterol in ether by ultraviolet of 3130 Á.5. The superior effectiveness of 2967 Á. in antirachitic activation of 7-dehydrocholesterol parallels the significant superiority of this wave length in inducing healing upon direct irradiation of depilated rachitic rats, which supports the hypothesis that 7-dehydrocholesterol is a significant precursor of vitamin D in the skin.Cambridge, Mass.

Attention is directed to the most striking instance of chemiluminescence which appears to have been observed and to the extraordinary advantages which the reaction possesses over the conventional cases. A simple economical two-stage synthesis of 3-aminophthalhydrazide is described which readily gives excellent yields of pure product. Specific directions are given for demonstration of its brilliant chemiluminescence in dilute aqueous alkaline oxidizing agents. THE STUDY of chemical reactions in which visible light is evolved at ordinary or low temperatures has largely been left to physics, physical chemistry, or biochemistry. Nevertheless, countless instances of such development of visible radiation are on record and many (if not most) involve organic compounds. However, in the vast majority of cases either the amount of light evolved is not impressive, or the reaction is brought about only under inconvenient conditions, or the substances involved are expensive or difficultly accessible. Partly for these reasons general attention to the matter has been but occasional and the most impressive and convenient illustration of the phenomenon appears to have been largely overlooked.Most chemiluminescent reactions are oxidations.Extensive resumes of hundreds of individual cases are already available.1 Of the many instances of organic compounds of known structure given in these references there appears to be a small group which gives a maximum of visible light. This group includes the following:(1) various reactions of Grignard compounds, such as the Wedekind2 reaction between chloropicrin and phenylmagnesium bromide in ether solution, the reaction of Grignard compounds with other nitro compounds,3 or the oxidation of various Grignard * Contribution No.

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Vol. 63 of bromobenzene in 100 cc. of ether. Refluxing started immediately, and the solution was stirred for three hours. After standing overnight, decomposition was effected with ammonium chloride. A tertiary carbinol (15.4 g.) was obtained on evaporation of the ether which melted at 100-101°after recrystallization from methanol and petroleum ether.10 As described by Blicke,10 this carbinol gave a yellow color with sulfuric acid which disappeared on dilu-(1) This paper is constructed from part of a dissertation submitted in March, 1941, by John S. Autenrieth to the Faculty of the Massachusetts Institute of Technology in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

polymer particles the rate of polymerization of styrene is proportional to the number of polymer particles present and is in dependent of the persulfate concentration. This can best be interpreted as indicating that the average number of free