1255 The above results appear to indicate that the conditions of Experiment 8 are to be preferred. To confirm this a series of ten determinations were made in accordance with those conditions, namely, 25 cc. of copper sulphate solution, representing 0.2533 gram of metallic copper, 25 cc. of the standard sulphuric acid, .5 gram of potassium nitrate, 4 amperes, IO volts at the outset, r 17 volts at the end of reduction, slowest speed and thirty minutes. The dish was not warmed at the outset of

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... experiment, or was external heat applied during electrolysis, although the liquid was considerably heated by the current, the final temperature being about 65" C. This continuous series was made in a single afternoon and no results were rejected; consequently they may be taken as representing the probable error of the method. The following are the percentages of nitrogen found, the theoretical value being 13.86 : Per cent. Per cent. Per cent. Per cent. Per cent.