The term "stationary" dissolvers is generally employed for "dispersion machines" with stationary impeller, mostly pole changeable, two-speed motors and a toothed disc not allowing any height adjustment. In our opinion, the use of this type of dissolvers does not provide satisfactory results. If required, the speed can be doubled, the power consumption, however, will then be 4 times as high. We believe that this ratio is too large, as most of the time the machine would then either be under- or overloaded. A matching to the product viscosity cannot be achieved.