Measurement of physical data during distillation

A correct boihng point is often not sufficient evidence for the purity of a component and it is therefore desirable to determine other properties during the course of a distdlation. This should preferably be done without removing distillate, and the determinations must then be performed in the stream of reflux at the column head. Such measurements will allow the conditions of distillation to be altered if necessary, at the proper moment. 

Continuous determinations of the following properties [59] are possible in laboratory and pilot plant columns  

With the last two, however, difficulties are experienced in keeping the liquid at a constant temperature, since the distillate temperature normally rises during distillation. 

Apparatus of Jantzen and Tiedcke for the determination of the melting point of high-melting fractions 

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