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Abstract. The major hydrological, morphometric and chemical features of Lake Urmia, a large salt lake in Iran, are briefly reviewed. Some comments are made on bacteriological quality of the lake sediments.

A controlled thermal explosion in which methyl isocyanide isomerises quantitatively to methyl cyanide has been studied in a calorimeter at 300 K. The enthalpy of isomerisation ΔH = −23.70 ± 0.14 (2 sdm) kcal mol−1, from which values of the enthalpies of formation of both gaseous and liquid methyl isocyanide are calculated.Similar measurements for ethyl isocyanide yield ΔH = −21.5 ± 1.0 kcal mol−1.

this iron(II) porphyrin and the vinylidene carbene derived from DDT.We are currently looking for the occurrence of such a carbene complex during reductive metabolization of DDT by microsomal cytochrome P 450 and studying the chemical properties of complex 1. References and notes(1) Used abbreviations: DDT = 2,2-bis(p-chlorophenyl)-1,1,1 -trlchloroethane; TPP = the dianlon of meso-tetraphenylporphyrln; DDD = 2,2-bls(p-chlorophenyl)-1,1 -dichloroethane; p-methyl-(or chloro-) TPP = the dianlon of meso-tetra-p-methyl-(or chloro-) phenylporphyrin.(2) D. A. Stotter,

The bimolecular rate constant for the direct reaction of chlorine atoms with methane was measured a t 25°C by using the very-low-pressure-pyrolysis technique. The rate constant was found to beIn addition, the ratio k&-l was observed with about 25% accuracy: