The spray cone angles produced by a plain-orifice effervescent atomizer are examined using three fluids whose viscosities range from 0.001 to 0.023 kg/ms (1 to 23 cp) and surface tensions from 0.030 to 0.080 kg/s2 (30 to 80 dynes/cm). Measurements of the visible spray cone angle were carried out over wide ranges of both air injection and ambient air pressures. The results obtained show that the sprays produced in effervescent atomization have appreciably wider cone angles than those produced by plain-orifice pressure atomizers. In general, spray angles are widened by reductions in liquid viscosity and surface tension and by increases in atomizing air injection pressure.