Experiments were carried out using glycerol-water and distilled water test solutions in a steam heated, stainless steel, natural circulation, vertical tube evaporator (i.d. 0.488 in., o.d. 0.731 in., heated length 4 ft.). The test liquid entered at its boiling point and the effects of concentration, overall temperature difference, and submergence on heat transfer were investigated. Maxima in heat transfer coefficients, due to the formation of minimum sized bubbles, were found to fade with increasing temperature difference and decreasing submergence because of the increasing influence of the forced convection mechanism over the nucleate boiling component. Experimental results from distilled water, and isopropyl alcohol-water, and normal propyl alcohol-water mixtures (from two previous workers) as well as those from water-glycerol were correlated by a modification of the Lockhart and Martinelli Parameter which included temperature and surface tension factors, and a term accounting for the distinctive features of boiling binary mixtures.