A good quality double wall insulated calorimeter which incorporates a coiled heating element and Styrofoam lining to reduce heat loss. Operating at 3-6V DC, 5 watts (approx.), the apparatus consists of a 150ml inner aluminium reservoir, an aluminium outer container and a Styrofoam inner lining and plastic insulator ring between the two containers. The lid supports a heating element connected to 4mm sockets, a stirrer and stopper with hole for a thermometer. The heating element coil can easily be removed and replaced if required.