KOTES
April, 1960 greater per cent. reduction in our other runs w a y probably due to accidental contamination of the CCI, phasc with traces of the highly active aqueour phase or some other radiocontainiiiaiit. The high relati1;e purity of the exchange system may be inferred a l ~ ofrom the fact that the equivalents of HC1 found was only 0.4-0.77, of the equivalents of C1, (in mitrast to 7 and 15% in Schulte’s two runs). The HCI can arise from Clz attacking H20 or stopcock grease in the system. Unpublished experiment iwe have made on the HCl*-CC14 exchange under comparable conditions indicate that it mould caontribute less than 1% based on the upper limit.; for oiir specific dark exchange rates. For the lattcr dark exchange we may take k 3X see.-’ and l i b 8 x lo-” liter mole-’ sec.-’ as conservative upper limits a t
