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E°in molar scale (ref. cell A) = +0.00977 volt; E°in molar scale (ref. cell B; see fig. 1) = +0.21245 volt.violet spectrophotometry which was adopted throughout as a routine.6 It is not unlikely that the reported discrepancies might be attributable to alcohol whose quality was not rigorously defined by the previous workers. The influence of traces of water in alcohol often referred to by some workers as the cause of the observed discrepancies was also looked into. It has been shown that about 0.02 molar solution of HC1 in ethanol could retain up to about 1.3% by vol. of water without any noticeable change in the observed e.m.f.; solutions of lower concentrations are, however, much more sensitive to addition of water.Conclusion. 1. The standard reduction potential of silver-silver chloride in ethanol is found to be +0.00977 volt in molar scale (i.e., +0.02190 volt in molal scale), the nature of the electrode process, as suggested thereby, is in agreement with that in aqueous medium, viz., AgCl + e -* Ag + Cl-. 2. The experimental value of mean activity co-efficients of HC1 in alcoholic solutions have been correlated with the Debye-Hückel equation taking into account the extended terms introduced in it. 3. Reproducibility and steadiness of the e.m.f. values of such systems seem to depend primarily on the state of purity and dryness of the medium which must be rigorously defined.

+ design of pulverized coal burners has developed largely THE as an industrial art. Coal characteristics, fineness of grinding, distribution of coal in the air stream, heat loss from the flame, and the aerodynamic pattern are factors that influence ignition and flame stability in pulverized coal burners. The interactions of these factors, and even the manner in which they individually influence the flame, are not fully understood. This arises in part because of opposing influences upon energy release in the flame and upon energy transfer processes that are responsible for ignition of the coal as it enters the flame.The purpose of the investigation was to study the influence of the different factors upon the ignition process independent of the influence of the same factors upon the resulting flame. For this purpose small flames were produced in an electrically heated furnace, so that most of the heat needed for ignition came from the furnace a t an independently controlled temperature rather than from the flame. EXPERIXIENTAL

Reactivity indices are presented for sixty-eight coals and thirty-five cokes. The indices, varying inversely with reactivity, are found to correlate with the volatile content on the dry ash-free basis. They are highest for cokes, decrease rapidly with increasing volatile in the anthracite range, are relatively constant for the medium-volatile bituminous coals, and again fall sharply for the highvolatile coals and lignites. Other factors probably influence