The heating of still pots and flasks

Stage and Gemuieker [104] have dealt with all aspects of evaporation and heating, including numerous constructional details. 

Electrical heating, on the other hand, is easily regulated. It can he applied in various forms  

Hol-plaiea with bare heating elements have the advantage of providing sensitive control, as is necessary, for instance, when the heat input is controlled by the pressure drop over the coUiiiin (cf. section 8.4) a covered hot-plate in this case has too long a temperature lag, which may result in flooding. It is advisable to leave an air space between the hot-plate and the fla.sk and to avoid heat losses by radiation as far as possible (Fig. 327). 

Another form of heating are the so-called mirror cookers or electric Bunsens. These burners depend on the concentration of the radiation emanating from an 

Heating elements with resistance wires conforming to the shapes of the surface.s to be heated are known as shaped heaters (Figs. 149, 184). If the contents of the flask are to be stirred electromagnetically an apparatus such as the one shown in Fig. 828 is convenient it combines a hot plate and a magnetic stirrer. 

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