The data in table 1 demonstrates clearly the undesirability of operating at the high vauum conditions which can be achieved with modern countercurrent rain condensers. In such a situation the drastic reduction in last effect HTC due to cool and viscous syrup can reduce vaporator capacity by 10% or more relative to more moderate conditions. The optimum operating range indicated is from 16 to 20 kPa absolute corresponding to saturation temperatures between 55°C and 60°C. in this case our findings are substantially in line with recognized practice (hugot).