Abstract: The present invention relates to a device for measuring heat evolution in a homogenous fluid sample. The device comprises: (i) a first chamber having a heat capacity C1 and an internal surface of area A1 defining a cavity for containing a volume V1 of the said fluid; (ii) a second chamber having a heat capacity C2 and an internal surface of area A2 defining a cavity for containing a volume V2 of the said fluid, wherein C1 is approximately equal to C2, A1 is approximately equal to A2 and V1 is greater than V2; (iii) means to detect and measure heat flow between the first and second chambers; and (iv) means to achieve a temperature equilibration between the two chambers.

Abstract: A temperature derivative sensing and regulating device and method is described which facilitates the maintainance of a very stable isothermal environment for an item, apparatus or facility or a constant rate of temperarture change. The device comprises a block of material having no internal heat sources, a thermal conductivity greater than 100 Wm.sup.1 K.sup.-1 and a specific heat capacity greater than 385 JK.sup.-1 kg.sup.-1. The block is surrounded by means for measuring the heat flow to and from the block and the device is further provided with means for generating a signal proportional to said heat flow and means for interfacing with the controller of a heating or cooling means associated with the item, apparatus or facility.