A method of preparing dough for bread or fancy cakes can be carried out more quickly, precisely and reliably, dispensing with subjective judgements of the dough during and/or after the mixing, in such a manner that the state of the dough is monitored with a measuring probe and that values for the further addition of measured amounts of a main constituent such as flour or in particular water are determined from measured values which are obtained at quite specific characteristic measuring moments, in order to obtain an optimum dough which has the required properties in a reproducible manner, regardless of the varying capacity of the flour to absorb water. Apparatus designed for this purpose contains a detecting element to pick up the nature of the material being mixed or the dough and an electrical evaluation device which in turn acts on a proportioning device for the addition of a main constituent of the dough, such as water for example, but can also be used to control or regulate the temperature of the added water the speed of rotation of the tools and further machine parameters.

Apparatus for determining the mechanical properties of particulate material comprises an outer member defining a cylindrical cavity, and an inner member rotatable in the cavity, the inner and outer members together defining a pulverizing chamber. The inner member has a pressure-bearing face facing the pulverizing chamber and a diametrically disposed groove in which a steel blade can be fitted so as to protrude into the pulverizing chamber. In use, the inner and outer members are rotated with respect to one another, while the particulate material in the pulverizing chamber is placed under axial compression. The torque transmitted from one member to the other, as well as the axial force transmitted from one member to the other is measured during the relative rotation, and these measurements used to determine the mechanical properties of the coal as well as the wear characteristics of the blade. There is further disclosed apparatus of a similar construction, for pulverizing a particulate material continuously, on a production scale, an auger being provided to feed the particulate material continuously into the pulverizing chamber, and there being an annular gap between the inner and outer members, through which pulverized material can escape.