AbstractA study was made of the evaporation from single drops containing solids. By means of a specially designed sensitive balance, drops were suspended over a hot‐air stream and their drying behavior was observed. Weight changes were measured during evaporation. Experimental data are presented on the time of appearance of the first solid phase and the formation of a solid crust for a wide range of drying conditions and materials. A theory is advanced for predicting the formation of a solid phase in drying a droplet containing a dissolved solid. This theory shows reasonable agreement with the experimental results. A tentative proposal for the application of the results to spray‐dryer performance is sugges